L-cysteine zwitterion — label CAS 52-90-4

L-cysteine zwitterion

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L-Cysteina, CAS 52-90-4

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MolGod_SDSCARD_1
REACH 2020/878
v2 · 15.07.2026
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🧬 3D Molecule Visualizer
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3D model L-(+)-Cysteine, CAS 52-90-4, molecular formula C3H7NO2S, molar mass 121.16 g/mol

Data transcribed from regulatory registers and technical literature, with the source and edition stated. It does not replace the supplier's safety data sheet. Fields without a recorded source are marked as such.

Chemical Overview: L-(+)-CysteineMolGod_OVERVIEW_1
Molecular formulaC3H7NO2S[1]
Molecular weight121.16 g/mol[1]
LogP (lipophilicity)-2.5[1]
IUPAC name(2R)-2-amino-3-sulfanylpropanoic acid[1]
SMILESC([C@@H](C(=O)O)N)S[1]
InChIKeyXUJNEKJLAYXESH-REOHCLBHSA-N[1]

Synonyms: L-cysteine · cysteine · 52-90-4 · Cystein · Thioserine

Data sources: PubChem (NLM/NIH)
Last updated: 2026-07-11

📚 Scientific references (Chicago Author-Date) (1 sources)
  1. PubChem. National Center for Biotechnology Information (NIH/NLM), chemical compound database. ↗ dotyczy: Molecular formula · Molecular weight · LogP (lipophilicity) · IUPAC name · SMILES · InChIKey

🎓 Badania akademickie: 52-90-4

#1🎓School of Chemistry and Pharmaceutical Engineering📅 2026
Enantioselective recognition and detection of cysteine using a three-dimensional Mn(1/3)Zn(2/3)CO(3)-rGO/CNT heterostructure-based molecularly imprinted sensor
Rao Y; Jian Q; Tan C; Yu X; Jiang X; Dai H.
Full LAB report →
#2🎓School of Medicine📅 2026
L-Cys-functionalized Zr-based MOF NU-1000: Fabrication and application as chiral stationary phase in open tubular capillary electrochromatography for chiral…
Zhu G; Qi L; Niu B; Zhang Q; Chen Q; Zhong D.
Full LAB report →
#3🎓National Institute of Research for Electrochemistry and Condensed Matter📅 2026
Novel silver nanoparticles decorated hybrid active film for the electrochemical determination of cysteine enantiomers
Tuchiu-Stanca BM; Stefan-van Staden RI; van Staden JKF.
Full LAB report → 🎓 University page
#4🎓College of Petrochemical Technology📅 2025
Enantioselective Recognition Driven Photocatalytic Degradation of d-Tryptophan Enantiomers Based on l-Cysteine-Modified β-Cyclodextrin
Zhao H; Wang J; Li H; Niu X; Xu H; Wang K.
Full LAB report →

SCIENTIFIC RESEARCH

[1]PubMed2024
Metal Ions Trigger the Gelation of Cysteine-Containing Peptide-Appended Coordination Cages
Li M; Zhu H; Adorinni S; Xue W; Heard A; Garcia AM. 2024. "Metal Ions Trigger the Gelation of Cysteine-Containing Peptide-Appended Coordination Cages." Angewandte Chemie (International ed. in English)
North China Electric Power University
Go to full study ↗
📊 Physicochemical properties

Quick Reference

Formula: C3H7NO2S
MW: 121.16 g/mol
CAS: 52-90-4
Appearance: Colorless crystals
🔬 Advanced Properties

Chemical Identifiers

SMILES: C([C@@H](C(=O)O)N)S

Last updated: 2026-07-11

Regulatory status of the substance
This substance is subject to regulatory requirements: hazardous waste management (BDO register). Details in the \"Regulatory Status (REACH/ECHA/CLP)\" section and on the SDS. Regulatory information — does not restrict purchase in this store.
🧮 Stoichiometry CalculatorMolGod_STOICH_1
🔍 External identifiersMolGod_EXTID_1
14 of 16 ID systems88%
DatabaseIdentifierActions
CAS Registry Number52-90-4Open →
PubChem CID5862[1]Open →
InChIKeyXUJNEKJLAYXESH-REOHCLBHSA-N[1]Open →
InChIInChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,…[1]
SMILESC([C@@H](C(=O)O)N)S[1]
EC Number200-158-2[2]Open →
ChEMBLCHEMBL863[3]Open →
DrugBankDB00151Open →
KEGG CompoundC00097Open →
HMDBHMDB0000574Open →
ChemSpider5653[4]Open →
MeSH UID (NLM)D003545Open →
UNII (FDA)K848JZ4886Open →
WikiData QIDQ186474Open →

Sources: PubChem (NIH), Wikidata SPARQL, KEGG, ChEMBL (EBI), CompTox CTX (EPA).

📚 Scientific references (Chicago Author-Date) (4 sources)
  1. PubChem. National Center for Biotechnology Information (NIH/NLM), chemical compound database. ↗ dotyczy: PubChem CID · InChIKey · InChI · SMILES
  2. ECHA. EC Inventory — EINECS, ELINCS, NLP and List Numbers assigned under REACH. Helsinki: European Chemicals Agency. ↗ dotyczy: EC Number
  3. ChEMBL. European Bioinformatics Institute (EMBL-EBI), bioactivity database. ↗ dotyczy: ChEMBL
  4. ChemSpider. Royal Society of Chemistry, chemical structure database. ↗ dotyczy: ChemSpider
📡 Spectroscopy — CAS 52-90-4MolGod_SPECHUB_MAIN
📊 Spectroscopic spectra databases — inline data 9 sources MolGod_SPECDB_2

Spectra are fetched on demand from 9 sources. Each spectrum is stored in our database — the next time it is opened there are zero requests to the external API. Download JCAMP-DX / CSV / PNG for every spectrum without searching.

IR IR (Infrared) — NIST WebBook
Public domain (US Federal)
▶ Click to load spectrum
🔗 Source
— points
📚 NIST Chemistry WebBook, SRD 69
MS (NIST) Mass Spectrum (EI) — NIST WebBook
Public domain (US Federal)
▶ Click to load spectrum
🔗 Source
— points
📚 NIST Standard Reference Database 1A
UV-Vis UV/Visible Absorption — NIST WebBook
Public domain (US Federal)
▶ Click to load spectrum
🔗 Source
— points
📚 NIST Chemistry WebBook, SRD 69
¹H NMR NMR (¹H, ¹³C) — NMRShiftDB
CC-BY-SA 4.0
▶ Click to load spectrum
🔗 Source
— points
📚 Steinbeck C et al. (2003) J. Chem. Inf. Comput. Sci. 43(1):10–16 DOI: 10.1021/ci025588g
MS (MoNA) MoNA — MassBank of North America
CC-BY 4.0
▶ Click to load spectrum
🔗 Source
— points
📚 MassBank of North America (UC Davis) DOI: 10.1002/jms.1777
IR/NMR/MS (SDBS) SDBS — Spectral Database for Organic Compounds (Japan AIST)
Free for non-commercial

Reference source — no public API. Open in an external database:

🔗 IR/NMR/MS (SDBS) →
📚 SDBSWeb: https://sdbs.db.aist.go.jp (AIST, Japan)
JP Monograph Japanese Pharmacopoeia — Monographs
Reference only

Reference source — no public API. Open in an external database:

🔗 JP Monograph →
📚 Japanese Pharmacopoeia 18th Edition (2021)
WHO INN WHO — International Nonproprietary Names
WHO Model Lists (free)

Reference source — no public API. Open in an external database:

🔗 WHO INN →
📚 WHO INN Programme
DOAJ DOAJ — Directory of Open Access Journals
OA journal index (mixed)

Reference source — no public API. Open in an external database:

🔗 DOAJ →
📚 DOAJ — doaj.org

Data is fetched once (JCAMP-DX parser) and stored in the plugin's local database. No duplicate downloads, no NIST queries on subsequent openings. Licences respected (only a deep link plus our own visualisation is published).

🔬 Interactive spectra (live — NIST / MoNA / NMRShiftDB / SDBS) (2)

Data retrieved live from multiple sources (priority chain). JCAMP-DX / CSV / PNG available for download under each spectrum.

IR — Fourier-transform infrared

Loading IR — Fourier-transform infrared…

MS — Mass spectrometry (EI 70eV)

Loading MS — Mass spectrometry (EI 70eV)…

📐 Physical & Chemical Properties (DB) 2 fields MolGod Score: No source
Property Value Unit Conditions Source
Water solubility 277 g/L 25°C No primary source
logP (octanol/water) -2.5 [1] — No primary source
📚 Scientific references (Chicago Author-Date) (1 sources)
  1. PubChem. National Center for Biotechnology Information (NIH/NLM), chemical compound database. ↗ dotyczy: logP (octanol/water)
🔄 Concentration unit converter LIVE MolGod_UNITCONV_1

Enter the L-(+)-Cysteine concentration in any unit — the rest will be calculated automatically.

MW: 121.16 g/mol · IUPAC Gold Book ↗

⚗️ Conversion formulas + citations (per formula)
ConversionFormulaAccuracySource
% (w/v) ↔ molarityc (mol/L) = (% × 10) / MW±0.5% rel. when density ≈ 1.0 g/mLIUPAC (2019)
millimolar ↔ molarc (mol/L) = mM × 10⁻³ExactCohen ER, Cvitaš T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor AJ (2007)
molarity (mol/L)c = n/V = (m/MW)/V±0.1% (depends on MW precision)IUPAC (2019)
parts per million (mg/L) ↔ molarityc (mol/L) = ppm / (1000 × MW); equivalently ppm = mg/L for dilute aqueous±1% (density-independent for dilute solutions)IUPAC (2019)
mg/mL ↔ molarityc (mol/L) = (mg/mL × 1000) / MW / 1000 = mg/mL / MW × 1±0.2%Cohen ER, Cvitaš T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor AJ (2007)
g/L ↔ molarityc (mol/L) = (g/L) / MW±0.1% (depends on MW precision)Cohen ER, Cvitaš T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor AJ (2007)
mmol/L ↔ molarityc (mol/L) = mmol/L × 10⁻³ExactCohen ER, Cvitaš T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor AJ (2007)
Celsius ↔ KelvinT(K) = t(°C) + 273.15±0.01 K (ITS-90 scale)BIPM (Bureau International des Poids et Mesures) (2019)
Celsius ↔ FahrenheitT(°F) = T(°C) × 9/5 + 32±0.1 °FThompson A, Taylor BN (2008)
density-corrected % ↔ molarityc (mol/L) = (%w/w × ρ × 10) / MW, ρ in g/mL±0.1% when ρ known to 3 decimalsCohen ER, Cvitaš T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor AJ (2007)
📚 Bibliography (8 authoritative sources)
  1. Thompson A, Taylor BN (2008). Guide for the Use of the International System of Units (SI). NIST Special Publication 811 · DOI: 10.6028/NIST.SP.811-2008
    → Primary SI standard for US scientific usage
  2. Cohen ER, Cvitaš T, Frey JG, Holmström B, Kuchitsu K, Marquardt R, Mills I, Pavese F, Quack M, Stohner J, Strauss HL, Takami M, Thor AJ (2007). Quantities, Units and Symbols in Physical Chemistry — The IUPAC Green Book. RSC Publishing, 3rd ed. · DOI: 10.1039/9781847557889 · ISBN: 978-0-85404-433-7
    → Canonical IUPAC guide for chemistry quantities/units
  3. BIPM (Bureau International des Poids et Mesures) (2019). The International System of Units (SI), 9th edition. BIPM · ↗
    → International SI definitions (incl. redefined kilogram 2019)
  4. ISO/IEC (2022). Quantities and units — Part 1: General. International Organization for Standardization — ISO 80000-1:2022 · ↗
    → General rules for physical quantities and units
  5. ISO/IEC (2019). Quantities and units — Part 9: Physical chemistry and molecular physics. International Organization for Standardization — ISO 80000-9:2019 · ↗
    → Concentration / molality / amount-of-substance conventions
  6. Tiesinga E, Mohr PJ, Newell DB, Taylor BN (2021). CODATA recommended values of the fundamental physical constants: 2018. Rev. Mod. Phys. 93(2):025010 · DOI: 10.1103/RevModPhys.93.025010
    → Avogadro, gas constant, molar volume (2019 SI revision)
  7. IUPAC (2019). Compendium of Chemical Terminology — the IUPAC Gold Book (online). IUPAC · DOI: 10.1351/goldbook
    → Definitions of mass fraction, molality, normality, ppm, activity
  8. Mills IM, Cvitaš T, Homann K, Kallay N, Kuchitsu K (1988). Quantities, Units and Symbols in Physical Chemistry. Blackwell Scientific Publications, 1st ed. · ISBN: 0-632-01773-5
    → Historical predecessor of IUPAC Green Book
🧪 Solution Preparation Wizard WIZARD MolGod_PREP_1
① Select concentration
② Target volume
③ Solvent

Calculations per: IUPAC Gold Book ↗, Merck ↗

🛡️ Safety — CAS 52-90-4MolGod_SAFEHUB_MAIN
Data limitations notice. The safety information on this page is for reference only and does not replace a full safety data sheet (SDS). Before using the product, consult the manufacturer's current safety data sheet and the GHS/CLP guidance. The CLP classification applies to the pure bulk substance, not to commercial formulations.

GHS/CLP classification — Regulation (EC) No 1272/2008 + UN GHS Rev. 9 (2021).

⚠ Warning
GHS07 — Irritant / harmful
GHS07 Irritant / harmful

🚨 Hazard statements (H)

  • H302 — Harmful if swallowed

🛡 Precautionary statements (P)

  • P264 — Wash thoroughly after handling
  • P270 — Do not eat, drink or smoke when using this product
  • P301+P312 — IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell
  • P330 — Rinse mouth
  • P501 — Dispose of contents/container to an approved waste collection point

⚠ Classification based on a consensus of sources (PubChem / supplier notifications) — not verified against the harmonised classification in Annex VI (CLP). The scope of hazards may be broader than the official classification; verify against the supplier's current safety data sheet before use.

Translations: CLP Regulation (EC) 1272/2008, Annexes III and IV. Data: PubChem/NLM.

📚 Consolidated scientific references — Chicago Author-Date 10 sources

References collected from all Safety Hub tabs. CAS: 52-90-4 · PubChem ↗

  1. Parlament Europejski i Rada UE. 2008. "Rozporządzenie (WE) nr 1272/2008 w sprawie klasyfikacji, oznakowania i pakowania substancji (CLP)." Dz.Urz. UE L 353. [↗] GHS, Regulations
  2. United Nations Economic Commission for Europe (UNECE). 2021. "Globally Harmonized System of Classification and Labelling of Chemicals (GHS), Ninth Revised Edition." United Nations, Geneva. [↗] GHS
  3. Goldfrank, Lewis R., Robert S. Hoffman, Mary Ann Howland, et al.. 2019. "Goldfrank's Toxicologic Emergencies, 11th ed.." McGraw-Hill Education, New York. ISBN 978-1-25-985961-8. Pierwsza pomoc, Toksykologia
  4. National Institute for Occupational Safety and Health (NIOSH). 2023. "NIOSH Pocket Guide to Chemical Hazards (DHHS Publ. 2005-149)." U.S. Department of Health and Human Services / CDC, Cincinnati, OH. [↗] Pierwsza pomoc, PPE, Toksykologia
  5. European Committee for Standardization (CEN). 2016. "EN 374-1:2016 — Protective gloves against dangerous chemicals and micro-organisms." CEN, Brussels. [↗] PPE
  6. UNECE. 2023. "European Agreement Concerning the International Carriage of Dangerous Goods by Road (ADR 2025)." United Nations, Geneva. [↗] Utylizacja, Regulacje
  7. National Fire Protection Association (NFPA). 2022. "NFPA 400 — Hazardous Materials Code." NFPA, Quincy, MA. [↗] Magazynowanie
  8. Urben, P.G. (ed.). 2017. "Bretherick's Handbook of Reactive Chemical Hazards, 8th ed.." Butterworth-Heinemann / Elsevier, Oxford. [↗] Magazynowanie
  9. Ministerstwo Klimatu i Środowiska RP. 2023. "Baza danych o produktach i opakowaniach oraz o gospodarce odpadami (BDO)." Ministerstwo Klimatu i Środowiska, Warszawa. [↗] Utylizacja
  10. International Agency for Research on Cancer (IARC / WHO). 2024. "IARC Monographs on the Identification of Carcinogenic Hazards to Humans — List of Classifications." WHO, Lyon. [↗] Toksykologia

Tabs with their own references (Emergency, PPE, Storage, Waste) contain additional bibliographic entries within their respective sections.

📈 Analytical statistics (t-test · RSD · Grubbs · Q-Dixon) ICH Q2

Paste a series of replicate measurements (CSV, or one number per line). The calculator computes the mean, standard deviation and 95% CI, and detects outliers (Grubbs + Dixon Q).

Separator: comma, space, tab, new line. Minimum 3 measurements.
📐 Statistical formulas
  • x̄ = Σxᵢ / n — arithmetic mean
  • s² = Σ(xᵢ - x̄)² / (n-1) — sample variance
  • s = √s² — standard deviation
  • RSD% = (s / x̄) × 100% — relative standard deviation
  • CI₉₅ = x̄ ± t(0.05, n-1) × s / √n — Student's t
  • G = |xᵢ - x̄| / s — Grubbs' test
  • Q = |xsuspect - xnearest| / |xmax - xmin| — Dixon Q-test

Source: ICH Q2(R2) Validation of Analytical Procedures · ICH PDF ↗

🧪 Buffer Recipe Calculator UNIQUE
References: pKa values from Goldberg NIST 81 · CRC Handbook 100th ed. · Stoll & Blanchard 1990 (DOI)

Choose a buffer from the list of 20 popular systems → enter the target pH → get an exact recipe with the masses to weigh out.

Step 1: Choose a buffer system

📜 Recipe history (last 10)
📊 HPLC method validation (ICH Q2(R1)) PARTIAL

3 of 3 critical metrics need experimental data

Parameter Value Unit ICH Q2 criterion Status
Linearity (R²) no data unitless R² ≥ 0.999 (≥0.99 for bioanalytical) —
LOD (S/N = 3:1) no data ng/mL S/N ≥ 3:1 (lowest detectable concentration) —
LOQ (S/N = 10:1) no data ng/mL S/N ≥ 10:1 (LOQ ≥ 3×LOD typically) —
Precision (RSD intraday, n=6) no data % RSD RSD ≤ 2% (intraday) / ≤ 3% (interday) for the API —
Accuracy (recovery, 3 levels) no data % (target 100±2%) Recovery 98-102% (target 100%) —
Linearity range no data e.g. 0.1-100 ng/mL Min. 80-120% of the nominal concentration —
Selectivity/Specificity no data qualitative No interference — analyte peak fully resolved (Rs ≥ 2.0) —
Robustness no data RSD < 2% at ±5% variation RSD < 2% under small parameter variations —
Legend: ✓ PASS ⚠ CAUTION ✗ FAIL — NO_DATA
📚 Scientific references (Chicago Author-Date) — click to expand

Analytical method validation standards — 4 independent sources (ICH + USP + AOAC + Snyder).

  1. International Conference on Harmonisation (ICH). 2005. Validation of Analytical Procedures: Text and Methodology Q2(R1). ICH Expert Working Group. [link ↗] — Gold-standard ICH guideline — accepted by EMA, FDA, MHLW, NMPA
  2. United States Pharmacopeia (USP) Convention. 2024. USP General Chapter <621> Chromatography. USP-NF 2024 ed. USP. [link ↗]
  3. AOAC International. 2016. Appendix F: Guidelines for Standard Method Performance Requirements. AOAC INTERNATIONAL. [link ↗] — AOAC SMPR — alternative to ICH Q2 for food/dietary supplements
  4. Snyder, Lloyd R., Joseph J. Kirkland, and John W. Dolan. 2010. Introduction to Modern Liquid Chromatography. 3rd ed. John Wiley & Sons. ISBN 978-0-470-16754-0. https://doi.org/10.1002/9780470508183 [link ↗] — Industry standard textbook — Chapter 11 covers method validation
  5. Snyder, L. R., J. J. Kirkland, and J. L. Glajch. 1997. Practical HPLC Method Development. 2nd ed. Wiley. ISBN 978-0-471-00703-6. — Classic method-development reference (DryLab heritage).
  6. Rozet, Eric, et al.. 2013. Analysis of recent pharmaceutical regulatory documents on analytical method validation. https://doi.org/10.1016/j.chroma.2007.03.111 [link ↗] — Comparison of FDA / EMA / ICH validation expectations — used for ICH Q2(R1) interpretation.
  7. Heyden, Yvan Vander, et al.. 2009. Robustness of pharmaceutical liquid chromatographic methods. https://doi.org/10.1016/j.jchromb.2008.10.052 [link ↗] — Plackett-Burman design for robustness — basis of ICH Q2 §3.7.
  8. Dong, Michael W.. 2019. HPLC and UHPLC for Practicing Scientists. 2nd ed. Wiley. ISBN 978-1-119-31378-3. https://doi.org/10.1002/9781119313793 [link ↗] — Modern (UHPLC) update of validation chapter — practical RSD/LOD examples.
  9. Meyer, Veronika R.. 2010. Practical High-Performance Liquid Chromatography. 5th ed. Wiley. ISBN 978-0-470-68218-0. — European pharmacopeial perspective — complements USP/AOAC.
  10. Kazakevich, Yuri V., and Rosario LoBrutto, eds.. 2007. HPLC for Pharmaceutical Scientists. Wiley-Interscience. ISBN 978-0-471-68162-4. https://doi.org/10.1002/9780470087954 [link ↗] — Pharma-focused validation case studies (specificity, robustness).
  11. European Medicines Agency (EMA). 2011. Guideline on bioanalytical method validation EMEA/CHMP/EWP/192217/2009. EMA Committee for Medicinal Products for Human Use. [link ↗] — EMA bioanalytical companion to ICH Q2(R1) for clinical samples.

· ⚠ SVHC/REACH regulatory warnings ↑

🔧 HPLC troubleshooting — decision tree 6 common problems

Diagnostics for the 6 most common HPLC problems with a decision tree (5 steps per problem). Source: Snyder/Kirkland/Dolan 3rd ed. Chapter 17 + LCGC LC Troubleshooting columns 1989-2024.

Broad peaks medium

Symptom: All peaks on the chromatogram are wider than expected (FWHM > 2× normal)

🔍 Diagnostic tree:
  1. 1. Check whether all peaks are broadened or only some
    → YES: All → instrumental problem (column or system)
    → NO: Only some → chemistry problem (interaction with the column for specific analytes)
  2. 2. Swap in a test column — does the problem disappear?
    → YES: COLUMN worn out — packing damaged, void in the first few mm. Replace it.
    → NO: Problem in the LC system
  3. 3. Check the dead volume — injection loop, connections, detector
    → YES: Loop > 100 µL for a 4.6 mm column or loose connections → replace ferrules, shorten tubing
    → NO: Continue diagnostics
  4. 4. Temperature test: raise the column from 25°C to 40°C
    → YES: Narrower peaks → mass-transfer kinetics too slow (increase T)
    → NO: Continue
  5. 5. Check flow rate vs the optimal van Deemter value for this column
    → YES: Optimum for 4.6mm/5µm = 1.0 mL/min, for 2.1mm/3µm = 0.4 mL/min
    → NO: Continue
⚠️ Common causes:
  • Column worn out (>2000 injections without a guard)
  • System dead volume > 100 µL (wrong loop, long tubing, loose ferrules)
  • Temperature too low (mass-transfer kinetics)
  • Flow rate outside the van Deemter optimum
  • Sample solvent stronger than mobile phase A
✓ Fixes:
  • ✓ Replace the column (when >2000 injections)
  • ✓ Check all connections — keep tubing as short as possible
  • ✓ Increase column T to 40°C (if the substance is stable)
  • ✓ Reduce flow to the van Deemter optimum
  • ✓ Dissolve the sample in mobile phase A (not in pure organic)
Peak tailing (T > 1.5) high

Symptom: Peaks have an extended "tail" on the late-elution side (asymmetry T = b/a > 1.5 per USP)

🔍 Diagnostic tree:
  1. 1. Does the substance contain basic groups (amino, pyridine)?
    → YES: Yes → silanol interactions! Add 0.1% TFA or 5-10 mM TEA to mobile phase A.
    → NO: Continue
  2. 2. Check the mobile-phase pH vs the substance pKa
    → YES: pH = pKa ± 1 → partial ionization, peak split. Move pH ≥ 2 units away from pKa.
    → NO: Continue
  3. 3. Check the column age (>1500 injections?)
    → YES: Yes → exposed silanols (column bleed). Replace with a column with higher endcapping (XTerra, Symmetry).
    → NO: Continue
  4. 4. Does the sample contain metals (Fe, Cu from glass vials)?
    → YES: Yes → use type II clear vials or PFA. Add 0.1mM EDTA to the sample.
    → NO: Continue
⚠️ Common causes:
  • Silanol interactions (basic analyte + silica gel free silanols)
  • pH at the boundary of the analyte pKa (peak split)
  • Old column (column bleed, high silanol activity)
  • Metals in the sample (chelation → tailing)
  • Column overload (>50 µg on a 4.6mm column)
✓ Fixes:
  • ✓ Add 0.1% TFA (UV) or 0.1% formic acid (LC-MS) to mobile phase A
  • ✓ Choose a column with high-purity endcapping: Waters XBridge BEH, Phenomenex Kinetex
  • ✓ Work at pH ≥ 2 units away from pKa
  • ✓ Add 0.1mM EDTA to the sample (Fe/Cu chelation)
  • ✓ Reduce the injection volume to ≤ 20 µL for a 4.6mm column
Baseline drift medium

Symptom: The baseline rises or falls systematically for >5 minutes

🔍 Diagnostic tree:
  1. 1. Are you running a gradient (B% increasing)?
    → YES: Yes → different absorption of phases A vs B at dλ. Solvent change in UV cutoff. Check the % organic UV absorbance.
    → NO: Continue (isocratic)
  2. 2. Check the column temperature — is it stable to ±0.5°C?
    → YES: Yes (stable) → continue
    → NO: Unstable → turn on the column thermostat (>25°C controlled)
  3. 3. Test: turn off the autosampler, run pump+column+detector alone
    → YES: Drift disappears → autosampler contamination (clean the needle, septum)
    → NO: Continue
  4. 4. Check the lamp age (D2 for UV)
    → YES: Yes (>1500 hours) → replace the lamp
    → NO: Continue
⚠️ Common causes:
  • Gradient elution with different UV cutoff of the phases
  • Unstable column T
  • Autosampler contamination of the needle/septum
  • Old UV lamp (>1500h)
  • Detector flow cell fouled
  • Column not equilibrated (<10 column volumes)
✓ Fixes:
  • ✓ Pre-equilibrate the column for 10-15 column volumes at 100% A
  • ✓ Column thermostat on, T 30-40°C stable
  • ✓ Clean the detector flow cell with 50:50 ACN:H2O
  • ✓ Replace the D2 lamp if >1500h
  • ✓ Use baseline subtraction (Chromeleon, Empower native function)
No peak / lost peak critical

Symptom: The expected analyte peak does not appear on the chromatogram

🔍 Diagnostic tree:
  1. 1. Did the injection actually take place?
    → YES: Check the autosampler log, pump pressure (should drop during injection)
    → NO: Autosampler problem → check the loop, needle, sample in the vial
  2. 2. Is the sample in the vial (correct volume, not evaporated)?
    → YES: Continue
    → NO: No sample — re-pipette
  3. 3. Sample stability — prepared >24h ago?
    → YES: Yes → degradation. Re-prepare a fresh sample.
    → NO: Continue
  4. 4. Check the detection wavelength vs the substance λmax
    → YES: Detection at λ does NOT match λmax → no signal. Scan DAD 200-400nm.
    → NO: Continue
  5. 5. Test: inject a pure standard (of known concentration, fresh)
    → YES: The standard gives a peak → problem with the sample (matrix, derivatization)
    → NO: No peak even with the standard → system problem (column, phase, gradient)
⚠️ Common causes:
  • Sample not drawn from the vial (autosampler bug)
  • Sample degraded (>24h pH/temp/light)
  • Detection at the wrong wavelength
  • Wrong mobile phase (e.g. forgotten TFA)
  • Column reversed / wrong stationary phase
  • Substance elutes at the front (V0) → unretained, not visible
✓ Fixes:
  • ✓ Re-prepare a fresh sample per the exact protocol
  • ✓ UV-Vis DAD scan 200-400nm + search for λmax
  • ✓ Check the mobile-phase composition — was TFA added?
  • ✓ Test the reverse column direction (carefully!)
  • ✓ For retention <1 min — lower the % B, MeOH instead of ACN
  • ✓ Check the expected retention time in the plugin method database
Pressure too high critical

Symptom: Pump pressure > 80% of the column max or system shutdown with a high-pressure error

🔍 Diagnostic tree:
  1. 1. Check that the column is connected correctly (arrow direction)
    → YES: OK
    → NO: Column reversed → flip it (never run it "backwards")
  2. 2. Test: remove the column from the system, run pump+detector alone
    → YES: Pressure drops to <50 bar → problem in the column (clogged)
    → NO: Pressure stays high → in-line filter clogged, frit fouled
  3. 3. Check the pre-column filter (in-line frit)
    → YES: Fouled and brown → replace it
    → NO: Continue
  4. 4. Back-flush the column with 50:50 ACN:H2O without the column — does it disappear?
    → YES: Particles stuck in the first mm — a 30 min flush may recover it
    → NO: Replace the column
⚠️ Common causes:
  • In-line filter (frit) clogged with particles
  • Buffer salting out (precipitation at high %B)
  • Sample contains suspended matter (filter 0.22 µm before injection)
  • Column clogged (column bed compaction)
  • Gradient with a buffer phase + high organic → salt precipitation
✓ Fixes:
  • ✓ ALWAYS filter the sample through 0.22 µm PVDF before injection
  • ✓ Replace the in-line filter every 100 injections (or when pressure rises >20%)
  • ✓ Do NOT use >20mM phosphate buffer + >70% ACN (the salt precipitates)
  • ✓ Flush the column for 30 min with 50:50 ACN:H2O in the reverse direction (when the manufacturer allows it)
  • ✓ Pre-column 4×3mm to protect the main column
Ghost peaks high

Symptom: Unexplained peaks on the chromatogram absent from the calibration

🔍 Diagnostic tree:
  1. 1. Test: blank injection (pure sample solvent)
    → YES: A ghost appears → contamination of the system or eluents
    → NO: Appears only with the sample → matrix
  2. 2. Does the ghost grow with the gradient (elutes at high %B)?
    → YES: Yes → overloaded column or strong-retained from a previous run
    → NO: Independent of the gradient → autosampler carryover
  3. 3. Increase carryover wash (between injections)
    → YES: Helps → carryover was to blame. Use a stronger wash protocol.
    → NO: Continue
  4. 4. Pure water injection — is there a peak?
    → YES: Yes → contamination of the water source (organics from the DI system)
    → NO: Continue
⚠️ Common causes:
  • Carryover in the autosampler needle/loop
  • Eluent contamination (even HPLC-grade)
  • Strong-retained components from previous runs
  • Plastic in the vials (phthalates, PEG from the caps)
  • Insufficiently purified DI water
✓ Fixes:
  • ✓ Strengthen the wash protocol: 100% B → 100% A → 50:50 (3 cycles)
  • ✓ Strong wash: 100% DMSO or 100% MeOH before calibration
  • ✓ Filter the eluents through 0.22 µm PTFE if in doubt
  • ✓ Use amber glass + Teflon-lined caps for samples
  • ✓ Periodic gradient ramp to 100% B for 10 min (clean-out)
📚 Scientific references (Chicago Author-Date) — click to expand
  1. Snyder, Lloyd R., Joseph J. Kirkland, and John W. Dolan. 2010. Introduction to Modern Liquid Chromatography. 3rd ed. John Wiley & Sons. Chapter 17 (Troubleshooting) pp. 559-616. ISBN 978-0-470-16754-0. https://doi.org/10.1002/9780470508183 [link ↗]
  2. Dolan, John W.. 2014. LC Troubleshooting (monthly column 1989-2024). LCGC North America. [link ↗] — John Dolan 35-letnia seria miesięcznych artykułów problemowych
  3. Kromidas, Stavros. 2017. HPLC Made to Measure: A Practical Handbook for Optimization. 2nd ed. Wiley-VCH. ISBN 978-3-527-31377-1. — Praktyczny przewodnik problem-solving dla labs analitycznych
  4. Dolan, John W.. 2013. When to Modify Method Conditions. 192-199. [link ↗] — Decision flow for changing flow rate / temperature / %B vs swapping columns.
  5. Dong, Michael W.. 2019. HPLC and UHPLC for Practicing Scientists. 2nd ed. Wiley. ISBN 978-1-119-31378-3. https://doi.org/10.1002/9781119313793 [link ↗] — Chapter 9 covers troubleshooting modern UHPLC systems (sub-2 µm particles).
  6. Meyer, Veronika R.. 2010. Practical High-Performance Liquid Chromatography. 5th ed. Wiley. ISBN 978-0-470-68218-0. — Solid step-by-step problem isolation chapter (eluents, columns, instruments).
  7. Snyder, L. R., J. J. Kirkland, and J. L. Glajch. 1997. Practical HPLC Method Development. 2nd ed. Wiley. ISBN 978-0-471-00703-6. — Method-development companion volume with troubleshooting cross-refs.
  8. Carr, Peter W.. 2009. The new physical chemistry of HPLC. 1764-1772. https://doi.org/10.1016/j.chroma.2008.11.094 [link ↗] — Theoretical basis for diagnosing efficiency losses (mass-transfer, eddy diffusion).
  9. Heyden, Yvan Vander, et al.. 2009. Robustness of pharmaceutical liquid chromatographic methods. 2120-2129. https://doi.org/10.1016/j.jchromb.2008.10.052 [link ↗] — How to diagnose method failures vs. system failures (Plackett-Burman).
  10. Engelhardt, Heinz. 2014. 100 Years of Chromatography. 2nd ed. Wiley-VCH. ISBN 978-3-527-33473-5. — Historical context for ghost-peak phenomenology (silica chemistry).
🧪 Solubility and solvent compatibility MolGod_SOLUB_1
Molecule
L-(+)-Cysteine
Formula
C3H7NO2S
logP (XLogP3)
-2.50
Mass (g/mol)
121.16
Polarity
Hydrophilic (polar)

⚠️ GC estimate (Hoftyzer–Van Krevelen). No literature HSP data for this CAS — precision ±2 MPa½. Verify experimentally.

Ra < R₀ = dobra mieszalność · Ra < 1,5×R₀ = graniczna · powyżej = słaba (R₀ — promień sfery Hansena tej molekuły) Dla tej molekuły R₀ = 8.

Solvent Compat. Ra Visual GC-MS HPLC Applications References
Water (H₂O)277 g/L (pomiar)—
✗ NieA (aqueous) (RP)
buffercell cultureanalyticalhydrophilic extraction
Ethanol (EtOH)——brak podstawy✗ NieA/B modifier (RP/NP)
extractionspectroscopy (UV-Vis)synthesisHPLC modifier
Methanol (MeOH)——brak podstawy✗ NieA/B (RP) (RP)
HPLC (eluent)LC-MSKarl FischerUV-transparent do 205 nm
Acetone——brak podstawy✗ NieB modifier (NP)
GC headspacecrystallizationdegreasingsynthesis
Acetonitrile (ACN)——brak podstawy✗ NieB (RP) (RP)
HPLC eluent (gold standard)LC-MS (wolny cut-off UV 190 nm)peptide analysis
DMSO——brak podstawy✗ NieN/A (N/A)
NMR (d6-DMSO)cell biology (cryopreservation)drug deliverysynthesis
THF——brak podstawy✗ NieB (NP) (NP)
GPC/SEC (polymer analysis)Grignard synthesisorganometallic
DCM (CH₂Cl₂)——brak podstawy✓ TakB (NP) (NP)
extractionNP-HPLCGC-MScrystallization (anti-solvent)
Chloroform (CHCl₃)——brak podstawy✓ TakN/A (toxic) (N/A)
NMR (CDCl3)lipid extraction (Folch method)NP-TLC
Hexane——brak podstawy✓ TakA (NP) (NP)
NP-HPLCoil extraction (lipids)GC-MSTLC (NP)
Toluene——brak podstawy✓ TakB (NP) (NP)
NMR (d8-toluene)synthesisDean-Stark azeotropic drying
📚 Scientific references for solvents (Chicago Author-Date) — click to expand

11 solvents · 54 full citations (NIST/CRC/IARC/Hansen/Reichardt/Smallwood/Wypych/Armarego/Snyder/GESTIS) — below.

Water (H₂O)
  1. NIST — NIST Chemistry WebBook — Water (CAS 7732-18-5)
  2. CRC — CRC Handbook of Chemistry and Physics, 104th ed., Sec. 8 (Properties of Water)
  3. IAPWS — IAPWS Release on Static Dielectric Constant of Water
  4. Reichardt 2011 — Solvents and Solvent Effects in Organic Chemistry
  5. GESTIS — GESTIS Substance Database — Water
Ethanol (EtOH)
  1. NIST — NIST Chemistry WebBook — Ethanol (CAS 64-17-5)
  2. CRC — CRC Handbook — Ethanol physical constants
  3. Snyder & Kirkland — Modern Liquid Chromatography — Ethanol eluotropic
  4. Smallwood — Handbook of Organic Solvent Properties — Ethanol
  5. GESTIS — GESTIS Substance Database — Ethanol
Methanol (MeOH)
  1. NIST — NIST Chemistry WebBook — Methanol (CAS 67-56-1)
  2. CRC — CRC Handbook — Methanol physical constants
  3. Snyder & Kirkland — Modern Liquid Chromatography — MeOH eluotropic, eo=0.95
  4. GESTIS — GESTIS Substance Database — Methanol
Acetone
  1. NIST — NIST Chemistry WebBook — Acetone (CAS 67-64-1)
  2. CRC — CRC Handbook — Acetone physical & thermodynamic constants
  3. Hansen 2007 — Hansen Solubility Parameters — Acetone (dD=15.5, dP=10.4, dH=7.0)
  4. Smallwood — Handbook of Organic Solvent Properties — Acetone
  5. GESTIS — GESTIS Substance Database — Acetone
Acetonitrile (ACN)
  1. NIST — NIST Chemistry WebBook — Acetonitrile (CAS 75-05-8)
  2. CRC — CRC Handbook — Acetonitrile constants
  3. Snyder & Kirkland — Modern Liquid Chromatography — ACN gold-standard HPLC eluent
  4. Reichardt 2011 — Solvents and Solvent Effects — ACN dipolar aprotic
  5. GESTIS — GESTIS Substance Database — Acetonitrile
DMSO
  1. NIST — NIST Chemistry WebBook — DMSO (CAS 67-68-5)
  2. Wypych 2019 — Handbook of Solvents Vol. 1 — DMSO comprehensive properties
  3. Hansen 2007 — HSP — DMSO (dD=18.4, dP=16.4, dH=10.2)
  4. Reichardt 2011 — Solvents and Solvent Effects — DMSO E_T(30)=45.1, dipolar aprotic
  5. GESTIS — GESTIS Substance Database — DMSO
THF
  1. NIST — NIST Chemistry WebBook — THF (CAS 109-99-9)
  2. Armarego 2009 — Purification of Laboratory Chemicals — THF drying & peroxide test
  3. Hansen 2007 — Hansen Solubility Parameters — THF (dD=16.8, dP=5.7, dH=8.0)
  4. Smallwood — Handbook of Organic Solvent Properties — THF
  5. GESTIS — GESTIS Substance Database — Tetrahydrofuran
DCM (CH₂Cl₂)
  1. NIST — NIST Chemistry WebBook — Dichloromethane (CAS 75-09-2)
  2. IARC 71 — IARC Monograph 71 — DCM (Group 2A carcinogen)
  3. Hansen 2007 — Hansen Solubility Parameters — DCM (dD=18.2, dP=6.3, dH=6.1)
  4. Reichardt 2011 — Solvents and Solvent Effects — DCM polarity index
  5. GESTIS — GESTIS Substance Database — Dichloromethane
Chloroform (CHCl₃)
  1. NIST — NIST Chemistry WebBook — Chloroform (CAS 67-66-3)
  2. IARC 73 — IARC Monograph 73 — Chloroform (Group 2B carcinogen)
  3. Hansen 2007 — Hansen Solubility Parameters — CHCl3 (dD=17.8, dP=3.1, dH=5.7)
  4. Reichardt 2011 — Solvents and Solvent Effects — CHCl3 H-bond donor strength
  5. GESTIS — GESTIS Substance Database — Chloroform
n-Hexane
  1. NIST — NIST Chemistry WebBook — n-Hexane (CAS 110-54-3)
  2. ATSDR n-Hexane — ATSDR Toxicological Profile for n-Hexane — neuropatia obwodowa (n-Heksan NIE jest kancerogenem IARC)
  3. Hansen 2007 — Hansen Solubility Parameters — n-Hexane (dD=14.9, dP=0, dH=0)
  4. Snyder & Kirkland — Modern Liquid Chromatography — n-Hexane NP standard, eo=0.00
  5. GESTIS — GESTIS Substance Database — n-Hexane
Toluene
  1. NIST — NIST Chemistry WebBook — Toluene (CAS 108-88-3)
  2. IARC 71 — IARC Monograph 71 — Toluene
  3. Hansen 2007 — Hansen Solubility Parameters — Toluene (dD=18.0, dP=1.4, dH=2.0)
  4. Smallwood — Handbook of Organic Solvent Properties — Toluene
  5. GESTIS — GESTIS Substance Database — Toluene
Solubility theory (applied in compatibility prediction):
  1. Yalkowsky, Samuel H., and Shri C. Valvani. 1980. "Solubility and Partitioning I: Solubility of Nonelectrolytes in Water." Journal of Pharmaceutical Sciences 69 (8): 912–922. https://doi.org/10.1002/jps.2600690814 — General Solubility Equation (GSE): logS = 0.5 − logP − 0.01(MP−25).
  2. Hansen, Charles M. 2007. Hansen Solubility Parameters: A User's Handbook. 2nd ed. CRC Press. https://doi.org/10.1201/9781420006834 — HSP triplet (dD, dP, dH) + Ra formula.
  3. Stefanis, E., and C. Panayiotou. 2008. "Prediction of Hansen Solubility Parameters with a New Group-Contribution Method." Int J Thermophys 29: 568–585. https://doi.org/10.1007/s10765-008-0415-z
  4. Reichardt, Christian, and Thomas Welton. 2011. Solvents and Solvent Effects in Organic Chemistry. 4th ed. Wiley-VCH. https://doi.org/10.1002/9783527632220 — E_T(30) polarity scale, solwatochromia.
  5. Snyder, Lloyd R., Joseph J. Kirkland, and John W. Dolan. 2010. Introduction to Modern Liquid Chromatography. 3rd ed. Wiley. https://doi.org/10.1002/9780470508183 — Eluotropic series, polarity index.
  6. Van Krevelen, D. W., and K. Te Nijenhuis. 2009. Properties of Polymers. 4th ed. Elsevier. https://doi.org/10.1016/B978-0-08-054819-7.X0001-5 — Hoftyzer–Van Krevelen group contribution dla dD/dP/dH z SMILES.
  7. Marcus, Yizhak. 1998. The Properties of Solvents. Wiley Series in Solution Chemistry, Vol. 4. ISBN 9780471983699 — Complete tabular set of 250+ solvents (ε, μ, donicity, acceptor numbers).
  8. PubChem Compound Database — CAS 52-90-4 lookup ↗ — logP (XLogP3), water solubility experimental + predicted.

Full bibliography in the REFERENCES accordion (at the bottom of the page) — Chicago Manual of Style 17th ed., Author-Date.

🧮 Laboratory calculators (8) MolGod_LABCALC_1
Dilution (C₁V₁=C₂V₂)
Molarity (M=n/V)
pH Buffer (Henderson-Hasselbalch)
Beer-Lambert (A=εcl)
Mass → Moles
Concentration % → M
ppm → mg/L
Temperature C↔F↔K

Verified formulas: IUPAC Gold Book ↗, DOI ↗

📊 Spectroscopic Databases MolGod_SPECDB_3
📋 Laboratory protocol generator MolGod_PROTOCOL_1

Protocol generated based on: GHS SDS, Aldrich Lab Guide ↗

🏷️ Label generator (QR) MolGod_LABEL_1
L-cysteine zwitterion• L-cysteine / cysteine• CAS: 52-90-4• Formula: C3H7NO2S• Mass: 121.16 g/molWARNINGGHS HAZARD STATEMENTS:(supplier self-classification — non-binding)H302: Harmful if swallowedP301+P312 P330 P501 P264 P270FOR LABORATORY USE ONLY!DH ScientificScience first. Commerce as consequence.Batch No.: Netto Mass: MFG:
Deskryptory Lipinskiego (struktura)

Drug-likeness radar chart (Lipinski Ro5 / Veber). Green zone = compliance with criteria.

Predictive data — properties calculated in silico (SMILES/RDKit). These do not replace clinical studies. Do not use for drug evaluation without experimental verification.

MW121.2LogP-2.5HBD3HBA4RotB2TPSA64.3 Ų
✓ Lipinski Ro5✓ Veber✓ Egan✗ Ghose (MW=121, LogP=-2.5)✗ REOS (MW=121)✗ Lead-like Ro3 (HBA=4)
PropertyValueRating
Absorption (GI)high✓
BBB permeabilityno
Bioavailability (Daina 2017)
55%
CYP450 profileCYP1A2 non-inhibitorCYP2C9 non-inhibitorCYP2C19 non-inhibitorCYP2D6 non-inhibitorCYP3A4 non-inhibitor
PAINS alerts1⚠
Brenk alerts0✓
pKa (pH 7.4)1.71 (curated)
hERG (cardiotox.)✓ no
P-gp substrate—
Ames mutagenicity✓ no
DILI (hepatotox.)—
LogS (aq. solub.)—
Sources (ADMET methodology)
  1. Lipinski, Christopher A., Franco Lombardo, Beryl W. Dominy, and Paul J. Feeney. 1997. "Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings." Advanced Drug Delivery Reviews 23 (1-3): 3-25.
  2. Veber, Daniel F., Stephen R. Johnson, Hung-Yuan Cheng, et al. 2002. "Molecular properties that influence the oral bioavailability of drug candidates." Journal of Medicinal Chemistry 45 (12): 2615-2623.
  3. Daina, Antoine, Olivier Michielin, and Vincent Zoete. 2017. "SwissADME: a free web tool to evaluate pharmacokinetics, drug-likeness and medicinal chemistry friendliness." Scientific Reports 7: 42717.
  4. Egan, William J., and Gregory Lauri. 2002. "Prediction of intestinal permeability." Advanced Drug Delivery Reviews 54 (3): 273-289.
  5. Baell, Jonathan B., and Georgina A. Holloway. 2010. "New substructure filters for removal of pan assay interference compounds (PAINS) from screening libraries." Journal of Medicinal Chemistry 53 (7): 2719-2740.
  6. Brenk, Ruth, Alessandro Schipani, Daniel James, et al. 2008. "Lessons learnt from assembling screening libraries for drug discovery for neglected diseases." ChemMedChem 3 (3): 435-444.
  7. Ertl, Peter, and Ansgar Schuffenhauer. 2009. "Estimation of synthetic accessibility score of drug-like molecules based on molecular complexity and fragment contributions." Journal of Cheminformatics 1: 8.
  8. Bickerton, G. Richard, Gaia V. Paolini, Jérémy Besnard, Sorel Muresan, and Andrew L. Hopkins. 2012. "Quantifying the Chemical Beauty of Drugs." Nature Chemistry 4 (2): 90-98.
  9. Hopkins, Andrew L., and Colin R. Groom. 2002. "The Druggable Genome." Nature Reviews Drug Discovery 1 (9): 727-730.
  10. Ghose, Arup K., Vellarkad N. Viswanadhan, and John J. Wendoloski. 1999. "A Knowledge-Based Approach in Designing Combinatorial or Medicinal Chemistry Libraries for Drug Discovery." Journal of Combinatorial Chemistry 1 (1): 55-68.
  11. Tice, Raymond R., Christopher P. Austin, Robert J. Kavlock, and John R. Bucher. 2013. "Improving the Human Hazard Characterization of Chemicals: A Tox21 Update." Environmental Health Perspectives 121 (7): 756-765.
  12. Leeson, Paul D., and Brian Springthorpe. 2007. "The Influence of Drug-Like Concepts on Decision-Making in Medicinal Chemistry." Nature Reviews Drug Discovery 6 (11): 881-890.
  13. Hann, Michael M. 2011. "Molecular Obesity, Potency and Other Addictions in Drug Discovery." MedChemComm 2 (5): 349-355.
  14. Davies, Mark, Michał Nowotka, George Papadatos, et al. 2015. "ChEMBL Web Services: Streamlining Access to Drug Discovery Data and Utilities." Nucleic Acids Research 43 (W1): W612-W620.
  15. Walters, W. Patrick, and Mark A. Murcko. 2002. "Prediction of 'Drug-Likeness.'". Advanced Drug Delivery Reviews 54 (3): 255–271. https://doi.org/10.1016/S0169-409X(02)00003-0.
  16. Congreve, Miles, Robin Carr, Christopher Murray, and Harren Jhoti. 2003. "A 'Rule of Three' for Fragment-Based Lead Discovery?" Drug Discovery Today 8 (19): 876–877. https://doi.org/10.1016/S1359-6446(03)02831-9.
  17. Brenk, Ruth, Alessandro Schipani, Daniel James, Agata Krasowski, Iain Hugh Gilbert, Julie Frearson, and Paul Graham Wyatt. 2008. "Lessons Learnt from Assembling Screening Libraries for Drug Discovery for Neglected Diseases." ChemMedChem 3 (3): 435-444.
  18. Schomburg, Karen T., Sascha Bietz, Hans Briem, Andrea M. Henzler, Stefan Urbaczek, and Matthias Rarey. 2014. "Facing the Challenges of Structure-Based Target Prediction by Inverse Virtual Screening." Journal of Chemical Information and Modeling 54 (6): 1676-1686.
  19. Bemis, Guy W., and Mark A. Murcko. 1996. "The Properties of Known Drugs. 1. Molecular Frameworks." Journal of Medicinal Chemistry 39 (15): 2887-2893.
  20. Schomburg, Karen T., and Matthias Rarey. 2014. "What Is the Potential of Structure-Based Target Prediction Methods?" Future Medicinal Chemistry 6 (17): 1987-1989.
  21. Requejo, Raquel, Ed T. Chouchani, Andrew M. James, Tracy A. Prime, Kerry-Lyn Lilley, Carmen Pesquero-Marin, and Michael P. Murphy. 2010. "Measuring Mitochondrial Protein Thiol Redox State." Methods in Enzymology 474: 123-147. ↗
  22. El Fatih Edris Abdel Karim. 1987. "Electrochemical analysis of the sulphoxide metabolites of s-carboxymethyl-l-cysteine." ↗
  23. Bolton, Evan E., Yanli Wang, Paul A. Thiessen, and Stephen H. Bryant. 2008. "PubChem: Integrated Platform of Small Molecules and Biological Activities." Annual Reports in Computational Chemistry 4: 217-241. [DOI ↗]
  24. Kim, Sunghwan, Jie Chen, Tiejun Cheng, et al. 2023. "PubChem 2023 update." Nucleic Acids Research 51 (D1): D1373-D1380. [DOI ↗]
  25. Kim, Sunghwan, Tiejun Cheng, Jianyong He, Chen Cheng, et al. 2021. "PubChem Protein, Pathway, Reaction, and Disease Specifications." Journal of Cheminformatics 13: 16. [DOI ↗]
  26. Hähnke, Volker D., Sunghwan Kim, and Evan E. Bolton. 2018. "PubChem chemical structure standardization." Journal of Cheminformatics 10: 36. [DOI ↗]
  27. Wang, Yanli, Stephen H. Bryant, Tiejun Cheng, Jiyao Wang, et al. 2017. "PubChem BioAssay: 2017 update." Nucleic Acids Research 45 (D1): D955-D963. [DOI ↗]
  28. Cheng, Tiejun, et al. 2014. "Computation of Octanol-Water Partition Coefficients by Guiding an Additive Model with Knowledge." Journal of Chemical Information and Modeling 54 (3): 793-805. [DOI ↗]
  29. Wilkinson, Mark D., et al. 2016. "The FAIR Guiding Principles for scientific data management and stewardship." Scientific Data 3: 160018. [DOI ↗]
  30. Hersey, Anne, et al. 2015. "Chemical databases: curation or integration by user-defined equivalence?" Drug Discovery Today: Technologies 14: 17-24.
  31. Veber, Daniel F., Stephen R. Johnson, Hung-Yuan Cheng, Brian R. Smith, Keith W. Ward, and Kenneth D. Kopple. 2002. "Molecular Properties That Influence the Oral Bioavailability of Drug Candidates." Journal of Medicinal Chemistry 45 (12): 2615-2623.
  32. ECHA. 2024. "REACH Guidance." European Chemicals Agency. ↗
  33. Groom, Colin R., Ian J. Bruno, Matthew P. Lightfoot, and Suzanna C. Ward. 2016. "The Cambridge Structural Database." Acta Crystallographica Section B 72 (2): 171-179. ↗
🧪 Solution preparation assistant (Smart Prep) MolGod_PREP_2

Enter what you want to prepare — I'll generate an SOP

Examples below — click to insert:
Preset recipes:
📚 Scientific literature overview — CAS 52-90-4MolGod_LITHUB_MAIN
⭐ Key findings (scientific literature) 3 publications
🏆 CAS 52-90-4 — multi-criteria ranking (W12): 30% citations · 20% recency · 20% topic · 15% historical · 15% open access.
  1. #1
    Václav Pokorný, Vojtěch Štejfa, Jakub Havlín et al. (2023) · Molecules
    Why it matters: Recent (2023) · open access
    SCORE 9.92 Mechanism Citations: 17 Open Access DOI ↗
  2. #2
    Meng J (2025) · Redox biology
    Why it matters: Recent (2025) · review · open access
    SCORE 7.05 Review Open Access DOI ↗ PubMed ↗
  3. #3
    Xu F, Huang H, Peng K et al. (2025) · Nature communications
    Why it matters: Recent (2025) · open access
    SCORE 7.05 Mechanism Open Access DOI ↗ PubMed ↗
📈 HPLC gradient — optimizer (LSS) TEMPLATE

Gradient based on PubChem XLogP3 + LSS (Snyder et al. 2010, ch. 9).

  • Column: C18
  • Buffer: phosphate
  • Flow: 1 mL/min
  • logP: -2.5 (PubChem XLogP3)
  • Ramp: 5% → 95% B, 10 min
  • Total analysis time: 23 min
t (min) %A %B flow (mL/min) Comment
0 95 5 1 start (equilibrium)
2 95 5 1 end of initial hold
12 5 95 1 end of LSS ramp
17 5 95 1 column wash
18 95 5 1 return to init
23 95 5 1 re-equilibration
📚 Scientific references (Chicago Author-Date)
  1. Snyder, Lloyd R., John W. Dolan, and Joseph J. Kirkland. 2010. Introduction to Modern Liquid Chromatography. Wiley. — Chapter 9 — gradient elution, LSS theory (cited as Snyder et al. 2010 in tool description).
  2. Schoenmakers, Peter J. 1986. Optimization of Chromatographic Selectivity: A Guide to Method Development. Elsevier. — Numerical optimization of gradient programs.
  3. Snyder, L. R., and J. W. Dolan. 2007. High-Performance Gradient Elution: The Practical Application of the Linear-Solvent-Strength Model. Wiley. — Foundational LSS reference for the %B_init = 5 + 8·logP heuristic implemented here.
  4. Nikitas, Pavlos, and Adrian Pappa-Louisi. 2009. "Retention models for isocratic and gradient elution in reversed-phase liquid chromatography." Journal of Chromatography A 1216: 1737-1755. [DOI ↗] — Modern review of gradient retention models — basis for non-LSS extensions.
  5. Carr, Peter W.. 2009. "The new physical chemistry of HPLC." Journal of Chromatography A 1216: 1764-1772. [DOI ↗]
  6. Dong, Michael W. 2019. HPLC and UHPLC for Practicing Scientists. Wiley. https://doi.org/10.1002/9781119313793. — Modern UHPLC gradient programming, sub-2 µm scaling rules.
  7. Wu, Naijun, and Anton M. Clausen. 2007. "Fundamental and practical aspects of ultrahigh pressure liquid chromatography for fast separations." Journal of Separation Science 30: 1167-1182. [DOI ↗]
  8. Stoll, Dwight R., and Peter W. Carr. 2017. "Two-Dimensional Liquid Chromatography: A State of the Art Tutorial." Analytical Chemistry 89: 519-531. [DOI ↗] — Reference for orthogonal gradient design (2D-LC second dimension).
  9. Dolan, John W.. 2013. "When to Modify Method Conditions." LCGC North America 31: 192-199.
  10. Meyer, Veronika R. 2010. Practical High-Performance Liquid Chromatography. Wiley. — Chapter 7 — practical gradient design with isokratyczny scouting.

REST: /wp-json/molgod/v1/hplc/gradient/52-90-4

📐 HPLC peak symmetry calculator (USP Tf / As)

Calculate the USP tailing factor (Tf) and asymmetry (As) from the peak half-widths. Enter a (left half-width) and b (right half-width) measured at 5% or 10% of peak height.

📚 References (Chicago Author-Date)
  1. USP General Chapter <621>. 2024. "Chromatography." United States Pharmacopeial Convention. [link ↗] — Defines USP Tailing Factor T = (a+b)/(2a) measured at 5% peak height.
  2. International Council for Harmonisation (ICH). 2023. "Validation of Analytical Procedures Q2(R2)." ICH Expert Working Group. [link ↗] — Tailing factor is a system suitability parameter (Section 6).
  3. Foley, Joe P., and John G. Dorsey. 1983. "Equations for calculation of chromatographic figures of merit for ideal and skewed peaks." Analytical Chemistry 55: 730-737 https://doi.org/10.1021/ac00255a033 [link ↗] — Original asymmetry factor As = b/a at 10% height (Foley & Dorsey 1983).
  4. Snyder, Lloyd R., Joseph J. Kirkland, and John W. Dolan. 2010. "Introduction to Modern Liquid Chromatography." Wiley. https://doi.org/10.1002/9780470508183 [link ↗] — Chapter 2.4 — peak shape diagnostics and remedies.
  5. Dolan, John W.. 2003. "Peak tailing and resolution." LCGC North America 21: 610-614 [link ↗] — How tailing factor degrades effective resolution.
  6. Vivó-Truyols, Gabriel, and Hans-Gerd Janssen. 2010. "Probabilistic approach to peak deconvolution in chromatography." Analytical Chemistry 82: 8525-8531 https://doi.org/10.1021/ac101742z [link ↗] — Modern numerical deconvolution for asymmetric peaks.
  7. Kromidas, Stavros. 2017. "HPLC Made to Measure: A Practical Handbook for Optimization." Wiley-VCH. — Practical Tf and As thresholds for routine QC.
  8. Dong, Michael W.. 2019. "HPLC and UHPLC for Practicing Scientists." Wiley. https://doi.org/10.1002/9781119313793 [link ↗]
  9. Meyer, Veronika R.. 2010. "Practical High-Performance Liquid Chromatography." Wiley.
  10. Heyden, Yvan Vander, et al.. 2009. "Robustness of pharmaceutical liquid chromatographic methods." Journal of Chromatography B 877: 2120-2129 https://doi.org/10.1016/j.jchromb.2008.10.052 [link ↗]
📊 Resolution and plate count calculator (Rs, N, H)

Calculate the resolution Rs, the number of theoretical plates N and HETP (H) for a pair of HPLC peaks. Enter the retention times, peak widths (at 50% or at the base) and the column length.

📚 References (Chicago Author-Date)
  1. Snyder, Lloyd R., Joseph J. Kirkland, and John W. Dolan. 2010. "Introduction to Modern Liquid Chromatography." 3rd ed. John Wiley & Sons. ISBN 978-0-470-16754-0. https://doi.org/10.1002/9780470508183 [link ↗] — Chapter 2 covers resolution, plate count and HETP fundamentals (Snyder et al. 2010).
  2. USP General Chapter <621>. 2024. "Chromatography." USP-NF 2024 ed. United States Pharmacopeial Convention. [link ↗] — Defines Rs >= 1.5 acceptance criterion and N calculation methods.
  3. Dolan, John W.. 2003. "How much resolution is enough?." LCGC North America 21: 350-353 [link ↗] — Practical guidance on Rs targets for routine method development.
  4. Van Deemter, J. J., F. J. Zuiderweg, and A. Klinkenberg. 1956. "Longitudinal diffusion and resistance to mass transfer as causes of nonideality in chromatography." Chemical Engineering Science 5: 271-289 https://doi.org/10.1016/0009-2509(56)80003-1 [link ↗] — Origin of N = 5.54·(tr/w0.5)² half-height plate count formulation.
  5. Giddings, J. Calvin. 1965. "Dynamics of Chromatography, Part I: Principles and Theory." Marcel Dekker. ISBN 978-0-8247-1357-7. — Resolution equation Rs = (1/4)·√N·(α-1)/α·k/(1+k) (master equation).
  6. Foley, Joe P., and John G. Dorsey. 1983. "Equations for calculation of chromatographic figures of merit for ideal and skewed peaks." Analytical Chemistry 55: 730-737 https://doi.org/10.1021/ac00255a033 [link ↗] — Skewed-peak corrections to apparent N.
  7. Knox, John H.. 1977. "Practical aspects of LC theory." Journal of Chromatographic Science 15: 352-364 https://doi.org/10.1093/chromsci/15.9.352 [link ↗]
  8. Carr, Peter W.. 2009. "The new physical chemistry of HPLC." Journal of Chromatography A 1216: 1764-1772 https://doi.org/10.1016/j.chroma.2008.11.094 [link ↗]
  9. Dong, Michael W.. 2019. "HPLC and UHPLC for Practicing Scientists." 2nd ed. Wiley. ISBN 978-1-119-31378-3. https://doi.org/10.1002/9781119313793 [link ↗]
  10. Meyer, Veronika R.. 2010. "Practical High-Performance Liquid Chromatography." 5th ed. Wiley. ISBN 978-0-470-68218-0.
🧪 System Suitability — live calculator (USP <621>)

Enter data from 5–6 injections (areas, tR, tailing, plates) — the calculator computes %RSD and means and checks compliance with USP <621>. You can paste CSV (comma-separated) or edit individual values.

📚 References (Chicago Author-Date)
  1. USP General Chapter <621>. 2024. "Chromatography (System Suitability section)." USP-NF 2024 ed. United States Pharmacopeial Convention. [link ↗] — Defines RSD area < 2%, tailing < 2.0, N > 2000 acceptance criteria.
  2. International Council for Harmonisation (ICH). 2023. "Validation of Analytical Procedures Q2(R2)." ICH Expert Working Group. [link ↗] — Section 5.4 — system suitability is part of method validation.
  3. US Food and Drug Administration (FDA). 2018. "Reviewer Guidance: Validation of Chromatographic Methods." US Food and Drug Administration. [link ↗] — CDER reviewer perspective on chromatographic validation expectations.
  4. Snyder, Lloyd R., Joseph J. Kirkland, and John W. Dolan. 2010. "Introduction to Modern Liquid Chromatography." 3rd ed. Wiley. — Chapter 2 — system suitability fundamentals (RSD, Tf, N).
  5. Heyden, Yvan Vander, et al.. 2009. "Robustness of pharmaceutical liquid chromatographic methods." — Robustness vs. system suitability — design-of-experiments framework.
  6. Rozet, Eric, et al.. 2013. "Analysis of recent pharmaceutical regulatory documents on analytical method validation."
  7. European Medicines Agency (EMA). 2011. "Guideline on bioanalytical method validation EMEA/CHMP/EWP/192217/2009." EMA. [link ↗] — EMA companion guideline with bioanalytical SS criteria.
  8. Dong, Michael W.. 2019. "HPLC and UHPLC for Practicing Scientists." 2nd ed. Wiley. — UHPLC-specific suitability adjustments (n=5 vs. n=6).
  9. Kazakevich, Yuri V., and Rosario LoBrutto, eds.. 2007. "HPLC for Pharmaceutical Scientists." Wiley-Interscience.
  10. AOAC International. 2016. "Appendix F: Guidelines for Standard Method Performance Requirements." AOAC INTERNATIONAL. [link ↗] — Alternative SS thresholds for food/dietary samples.
⚗️ Jonizacja w funkcji pH (Henderson-Hasselbalch)MolGod_PHION_1

Typ: Amfoteryczny · pKa: 1.71 · pKa2: 10.78

024681012140%50%100%% zjonizowany% niejonowypH
pH% jonowy% niejonowy
098.1 %1.9 %
233.9 %66.1 %
40.5 %99.5 %
60.0 %100.0 %
80.2 %99.8 %
1014.2 %85.8 %
1294.3 %5.7 %
1499.9 %0.1 %
Źródła dla tej substancji (12)
  • CRC Handbook 91st ed.
    Lide, David R., ed. 2010. CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press.
  • CRC Handbook 105th ed.
    Rumble, John R., Thomas J. Bruno, Maria J. Doa, and Donald R. Burgess, eds. 2024. CRC Handbook of Chemistry and Physics. 105th ed. Boca Raton, FL: CRC Press.
  • NIST WebBook — link
    Linstrom, Peter J., and William G. Mallard, eds. 2024. NIST Chemistry WebBook. NIST Standard Reference Database Number 69. Gaithersburg, MD: National Institute of Standards and Technology.
  • PubChem CID 5862 — link
    Kim, Sunghwan, Jie Chen, Tiejun Cheng, Asta Gindulyte, Jia He, Siqian He, Qingliang Li, et al. 2023. "PubChem 2023 update." Nucleic Acids Research 51 (D1): D1373-D1380. PubChem CID 5862.
  • DrugBank DB00151 — link
    Knox, Craig, Mike Wilson, Christen M. Klinger, Mark Franklin, Eponine Oler, Alex Wilson, Allison Pon, et al. 2024. "DrugBank 6.0: the DrugBank Knowledgebase for 2024." Nucleic Acids Research 52 (D1): D1265-D1275. DrugBank ID DB00151.
  • ChEMBL CHEMBL602 — link
    Zdrazil, Barbara, Eloy Felix, Fiona Hunter, Emma J. Manners, James Blackshaw, Sybilla Corbett, Marleen de Veij, et al. 2024. "The ChEMBL Database in 2023." Nucleic Acids Research 52 (D1): D1180-D1192. ChEMBL ID CHEMBL602.
  • KEGG COMPOUND C00097 — link
    Kanehisa, Minoru, Miho Furumichi, Yoko Sato, Masayuki Kawashima, and Mari Ishiguro-Watanabe. 2023. "KEGG for taxonomy-based analysis of pathways and genomes." Nucleic Acids Research 51 (D1): D587-D592.
  • IUPAC
    Serjeant, E. P., and Boyd Dempsey. 1979. Ionisation Constants of Organic Acids in Aqueous Solution. IUPAC Chemical Data Series No. 23. Oxford: Pergamon Press.
  • IUPAC
    Perrin, Douglas D. 1965. Dissociation Constants of Organic Bases in Aqueous Solution. IUPAC. London: Butterworths.
  • NIST
    Goldberg, Robert N., Nand Kishore, and Rebecca Lennen. 2002. "Thermodynamic Quantities for the Ionization Reactions of Buffers." Journal of Physical and Chemical Reference Data 31 (2): 231-370.
  • Textbook
    Nelson, David L., and Michael M. Cox. 2017. Lehninger Principles of Biochemistry. 7th ed. New York: W. H. Freeman.
Bibliografia metody (Chicago)
  • Henderson, L. J. 1908. "Concerning the Relationship between the Strength of Acids and Their Capacity to Preserve Neutrality." American Journal of Physiology 21 (4): 173-179.
  • Hasselbalch, K. A. 1917. "Die Berechnung der Wasserstoffzahl des Blutes aus der freien und gebundenen Kohlensäure desselben." Biochemische Zeitschrift 78: 112-144.
  • Po, Henry N., and N. M. Senozan. 2001. "The Henderson-Hasselbalch Equation: Its History and Limitations." Journal of Chemical Education 78 (11): 1499-1503.
  • Avdeef, Alex. 2012. "Absorption and Drug Development: Solubility, Permeability, and Charge State." 2nd ed. Wiley.
  • Avdeef, Alex. 2007. "Solubility of sparingly-soluble ionizable drugs." Advanced Drug Delivery Reviews 59 (7): 568-590.
  • Volgyi, Gergely, et al. 2007. "Potentiometric and spectrophotometric pKa determination of water-insoluble compounds." Analytica Chimica Acta 583 (2): 418-428.
  • Fini, Adamo, Giuseppe Fazio, and Giuseppina Feroci. 1997. "Solubility and solubilization properties of non-steroidal anti-inflammatory drugs." Pharmaceutica Acta Helvetiae 70 (4): 305-318.
  • Mauger, John W., Anthony N. Paruta, and Robert J. Gerraughty. 1972. "Solubilities of sulfadiazine, sulfisomidine, and sulfadimethoxine." Journal of Pharmaceutical Sciences 61 (1): 94-97.
  • Lyman, Warren J., William F. Reehl, and David H. Rosenblatt. 1990. "Handbook of Chemical Property Estimation Methods." American Chemical Society.
  • Marcus, Yizhak. 1998. "The Properties of Solvents." Wiley.
  • Serjeant, E. P., and Boyd Dempsey. 1979. Ionisation Constants of Organic Acids in Aqueous Solution. IUPAC Chemical Data Series No. 23. Oxford: Pergamon Press.
  • Perrin, Douglas D. 1965. Dissociation Constants of Organic Bases in Aqueous Solution. IUPAC. London: Butterworths.
  • Goldberg, Robert N., Nand Kishore, and Rebecca Lennen. 2002. "Thermodynamic Quantities for the Ionization Reactions of Buffers." Journal of Physical and Chemical Reference Data 31 (2): 231-370.
  • Rumble, John R., Thomas J. Bruno, Maria J. Doa, and Donald R. Burgess, eds. 2024. CRC Handbook of Chemistry and Physics. 105th ed. Boca Raton, FL: CRC Press.
  • Lide, David R., ed. 2010. CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press.
  • Kim, Sunghwan, Jie Chen, Tiejun Cheng, Asta Gindulyte, Jia He, Siqian He, Qingliang Li, et al. 2023. "PubChem 2023 update." Nucleic Acids Research 51 (D1): D1373-D1380.
  • Knox, Craig, Mike Wilson, Christen M. Klinger, Mark Franklin, Eponine Oler, Alex Wilson, Allison Pon, et al. 2024. "DrugBank 6.0: the DrugBank Knowledgebase for 2024." Nucleic Acids Research 52 (D1): D1265-D1275.
  • Zdrazil, Barbara, Eloy Felix, Fiona Hunter, Emma J. Manners, James Blackshaw, Sybilla Corbett, Marleen de Veij, et al. 2024. "The ChEMBL Database in 2023." Nucleic Acids Research 52 (D1): D1180-D1192.
  • Kanehisa, Minoru, Miho Furumichi, Yoko Sato, Masayuki Kawashima, and Mari Ishiguro-Watanabe. 2023. "KEGG for taxonomy-based analysis of pathways and genomes." Nucleic Acids Research 51 (D1): D587-D592.
  • Linstrom, Peter J., and William G. Mallard, eds. 2024. NIST Chemistry WebBook. NIST Standard Reference Database Number 69. Gaithersburg, MD: National Institute of Standards and Technology.
  • Nelson, David L., and Michael M. Cox. 2017. Lehninger Principles of Biochemistry. 7th ed. New York: W. H. Freeman.
🔄 Analiza chiralna / enancjomery chiralnaMolGod_CHIRAL_1

Stereochemia, skręcalność właściwa i rekomendowana kolumna chiralna HPLC dla CAS 52-90-4 (CIP per Cahn-Ingold-Prelog 1966).

Predictive data — CIP configuration derived from the SMILES structure. Specific rotation and column selection are estimated values. Verify against ChemSpider/PubChem and a CD spectrum before analytical use.

Centra stereogeniczne
1
Konfiguracja
(R) — konfiguracja absolutna (CIP)
Skręcalność właściwa [α]D20
9,40°
(+) prawoskrętne • rozp.: 1 N HCl • c=2, 25°C
Enancjomer (para)
CAS 921-01-7
Rekomendowana kolumna HPLC
Crownpak CR(+)
Faza ruchoma (eluent)
HClO4(aq) pH 1.5
Bibliography (Chicago author-date)
  • Eliel, Ernest L., Samuel H. Wilen, and Lewis N. Mander. 1994. "Stereochemistry of Organic Compounds." New York: Wiley.
  • Cahn, Robert S., Christopher Ingold, and Vladimir Prelog. 1966. "Specification of Molecular Chirality." Angewandte Chemie International Edition 5 (4): 385-415. https://doi.org/10.1002/anie.196603851.
  • Subramanian, Ganapathy, ed. 2007. "Chiral Separation Techniques: A Practical Approach." 3rd ed. Weinheim: Wiley-VCH.
  • Francotte, Eric, and Wolfgang Lindner, eds. 2006. "Chirality in Drug Research." Weinheim: Wiley-VCH.
  • U.S. FDA. 1992. "FDA's Policy Statement for the Development of New Stereoisomeric Drugs." Chirality 4 (5): 338-340. https://doi.org/10.1002/chir.530040513.
  • Patani, George A., and Edmond J. LaVoie. 1996. "Bioisosterism: A Rational Approach in Drug Design." Chemical Reviews 96 (8): 3147-3176.
  • Meanwell, Nicholas A. 2011. "Synopsis of Some Recent Tactical Application of Bioisosteres in Drug Design." Journal of Medicinal Chemistry 54 (8): 2529-2591.
  • Davies, Mark, Michał Nowotka, George Papadatos, et al. 2015. "ChEMBL Web Services: Streamlining Access to Drug Discovery Data and Utilities." Nucleic Acids Research 43 (W1): W612-W620.
  • Easson, Leslie H., and Edgar Stedman. 1933. "Studies on the relationship between chemical constitution and physiological action: molecular dissymmetry and physiological activity." Biochemical Journal 27 (4): 1257-1266. https://doi.org/10.1042/bj0271257.
  • Pirkle, William H., and Thomas C. Pochapsky. 1989. "Considerations of chiral recognition relevant to the liquid chromatography separation of enantiomers." Chemical Reviews 89 (2): 347-362. https://doi.org/10.1021/cr00092a006.
  • Dale, James A., and Harry S. Mosher. 1973. "Nuclear magnetic resonance enantiomer reagents: configurational correlations via nuclear magnetic resonance chemical shifts of diastereomeric mandelate, O-methylmandelate, and α-methoxy-α-trifluoromethylphenylacetate (MTPA) esters." Journal of the American Chemical Society 95 (2): 512-519. https://doi.org/10.1021/ja00783a034.
  • Beesley, Thomas E., and Raymond P. W. Scott. 1998. Chiral Chromatography. Chichester: John Wiley & Sons.
  • Allenmark, Stig G. 1991. Chromatographic Enantioseparation: Methods and Applications. 2nd ed. New York: Ellis Horwood.
  • Wainer, Irving W., ed. 1993. Drug Stereochemistry: Analytical Methods and Pharmacology. 2nd ed. New York: Marcel Dekker.
  • Aboul-Enein, Hassan Y., and Irving W. Wainer, eds. 1997. The Impact of Stereochemistry on Drug Development and Use. New York: John Wiley & Sons.
  • Ahuja, Satinder, ed. 2000. Chiral Separations by Liquid Chromatography. ACS Symposium Series 471. Washington, DC: American Chemical Society.
  • Maier, Norbert M., Pilar Franco, and Wolfgang Lindner. 2001. "Separation of enantiomers: needs, challenges, perspectives." Journal of Chromatography A 906 (1-2): 3-33. https://doi.org/10.1016/S0021-9673(00)00532-X.
  • Schurig, Volker. 2001. "Separation of enantiomers by gas chromatography." Journal of Chromatography A 906 (1-2): 275-299. https://doi.org/10.1016/S0021-9673(00)00505-7.
  • Berthod, Alain. 2009. "Chiral recognition mechanisms with macrocyclic glycopeptide selectors." Chirality 21 (1): 167-175. https://doi.org/10.1002/chir.20600.
  • Okamoto, Yoshio, and Eiji Yashima. 1998. "Polysaccharide derivatives for chromatographic separation of enantiomers." Angewandte Chemie International Edition 37 (8): 1020-1043. https://doi.org/10.1002/(SICI)1521-3773(19980504)37:8<1020::AID-ANIE1020>3.0.CO;2-5.
  • Lämmerhofer, Michael. 2010. "Chiral recognition by enantioselective liquid chromatography: mechanisms and modern chiral stationary phases." Journal of Chromatography A 1217 (6): 814-856. https://doi.org/10.1016/j.chroma.2009.10.022.
  • Caner, Hava, Eli Groner, Liron Levy, and Israel Agranat. 2004. "Trends in the development of chiral drugs." Drug Discovery Today 9 (3): 105-110. https://doi.org/10.1016/S1359-6446(03)02904-0.
  • Agranat, Israel, Hava Caner, and John Caldwell. 2002. "Putting chirality to work: the strategy of chiral switches." Nature Reviews Drug Discovery 1 (10): 753-768. https://doi.org/10.1038/nrd915.
  • Crosby, John. 1991. "Synthesis of optically active compounds: a large-scale perspective." Tetrahedron 47 (27): 4789-4846. https://doi.org/10.1016/S0040-4020(01)80950-6.
  • Nguyen, Lien Ai, Hua He, and Chuong Pham-Huy. 2006. "Chiral drugs: an overview." International Journal of Biomedical Science 2 (2): 85-100.
  • Eriksson, Tommy, Sven Björkman, and Peter Höglund. 2001. "Clinical pharmacology of thalidomide." European Journal of Clinical Pharmacology 57 (5): 365-376. https://doi.org/10.1007/s002280100320.
  • Evans, Andrew M. 2007. "Comparative pharmacology of S(+)-ibuprofen and (RS)-ibuprofen." Clinical Rheumatology 20 (Suppl 1): S9-S14. https://doi.org/10.1007/BF03342661.
  • IUPAC. 1996. "Basic terminology of stereochemistry (IUPAC recommendations 1996)." Pure and Applied Chemistry 68 (12): 2193-2222. https://doi.org/10.1351/pac199668122193.
  • Mislow, Kurt, and Jay Siegel. 1984. "Stereoisomerism and local chirality." Journal of the American Chemical Society 106 (11): 3319-3328. https://doi.org/10.1021/ja00323a043.
  • Francotte, Eric R. 2001. "Enantioselective chromatography as a powerful alternative for the preparation of drug enantiomers." Journal of Chromatography A 906 (1-2): 379-397. https://doi.org/10.1016/S0021-9673(00)00951-1.
  • Welch, Christopher J. 1994. "Evolution of chiral stationary phase design in the Pirkle laboratories." Journal of Chromatography A 666 (1-2): 3-26. https://doi.org/10.1016/0021-9673(94)80367-6.
  • Armstrong, Daniel W., Yibing Tang, Shengsheng Chen, et al. 1994. "Macrocyclic antibiotics as a new class of chiral selectors for liquid chromatography." Analytical Chemistry 66 (9): 1473-1484. https://doi.org/10.1021/ac00081a019.
  • Pirkle, William H., Donn W. House, and Jerald M. Finn. 1980. "Broad spectrum resolution of optical isomers using chiral high-performance liquid chromatographic bonded phases." Journal of Chromatography A 192 (1): 143-158. https://doi.org/10.1016/S0021-9673(80)80043-3.
  • European Directorate for the Quality of Medicines & HealthCare. 2024. European Pharmacopoeia 11.5: Chapter 2.2.7 Optical rotation. Strasbourg: EDQM Council of Europe.
  • United States Pharmacopeial Convention. 2024. USP-NF General Chapter <781> Optical Rotation. Rockville, MD: USP.
  • Gal, Joseph. 2017. "Pasteur and the art of chirality." Nature Chemistry 9 (7): 604-605. https://doi.org/10.1038/nchem.2790.
  • Pasteur, Louis. 1848. "Mémoire sur la relation qui peut exister entre la forme cristalline et la composition chimique, et sur la cause de la polarisation rotatoire." Comptes rendus de l'Académie des sciences 26: 535-538.
  • Le Bel, Joseph A. 1874. "Sur les relations qui existent entre les formules atomiques des corps organiques et le pouvoir rotatoire de leurs dissolutions." Bulletin de la Société Chimique de France 22: 337-347.
  • van 't Hoff, Jacobus Henricus. 1874. "Voorstel tot uitbreiding der tegenwoordige in de scheikunde gebruikte structuur-formules in de ruimte, benevens een daarmede samenhangende opmerking omtrent het verband tusschen optisch actief vermogen en chemische constitutie van organische verbindingen." Utrecht: J. Greven.
Extended bibliography — 4 sources (PubMed/CrossRef/EuropePMC)
  • PUBRao Y; Jian Q; Tan C; Yu X; Jiang X; Dai H. 2026. "Enantioselective recognition and detection of cysteine using a three-dimensional Mn(1/3)Zn(2/3)CO(3)-rGO/CNT heterostructure-based molecularly imprinted sensor." Analytical methods : advancing methods and applications. https://doi.org/10.1039/d5ay01993a.
  • PUBZhu G; Qi L; Niu B; Zhang Q; Chen Q; Zhong D. 2026. "L-Cys-functionalized Zr-based MOF NU-1000: Fabrication and application as chiral stationary phase in open tubular capillary electrochromatography for chiral separation." Journal of chromatography. A. https://doi.org/10.1016/j.chroma.2026.466716.
  • PUBTuchiu-Stanca BM; Stefan-van Staden RI; van Staden JKF. 2026. "Novel silver nanoparticles decorated hybrid active film for the electrochemical determination of cysteine enantiomers." Analytica chimica acta. https://doi.org/10.1016/j.aca.2025.344836.
  • PUBLi M; Zhu H; Adorinni S; Xue W; Heard A; Garcia AM. 2024. "Metal Ions Trigger the Gelation of Cysteine-Containing Peptide-Appended Coordination Cages." Angewandte Chemie (International ed. in English). https://doi.org/10.1002/anie.202406909.
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📚 REFERENCES (Aggregate bibliography, Chicago Author-Date) 126 items

All scientific sources cited in the accordions above for CAS 52-90-4. Format: Chicago Manual of Style 17th ed., Author-Date system.

🗄️ Scientific databases

  1. NIST. n.d. NIST Chemistry WebBook: CAS 52-90-4. Gaithersburg, MD: National Institute of Standards and Technology. https://webbook.nist.gov/cgi/cbook.cgi?ID=52-90-4.
  2. AIST. n.d. Spectral Database for Organic Compounds (SDBS): CAS 52-90-4. Tsukuba, Japan: National Institute of Advanced Industrial Science and Technology. https://sdbs.db.aist.go.jp/.
  3. Linstrom, Peter J., and William G. Mallard, eds. n.d. NIST Chemistry WebBook: NIST Standard Reference Database Number 69. Gaithersburg, MD: National Institute of Standards and Technology. https://doi.org/10.18434/T4D303.
  4. PubChem. n.d. PubChem Compound Summary: CAS 52-90-4. Bethesda, MD: National Center for Biotechnology Information (NCBI), National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/#query=52-90-4.
  5. U.S. EPA. n.d. CompTox Chemicals Dashboard: CAS 52-90-4. Research Triangle Park, NC: U.S. Environmental Protection Agency. https://comptox.epa.gov/dashboard/chemical/details/DTXSID8022876.

📐 Standards / Guidelines

  1. ICH. 2003. "Stability Testing of New Drug Substances and Products: Q1A(R2)." Geneva: International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. https://database.ich.org/sites/default/files/Q1A%28R2%29%20Guideline.pdf.
  2. National Fire Protection Association (NFPA). 2024. "NFPA 30: Flammable and Combustible Liquids Code." NFPA, Quincy, MA. https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=30.
  3. Occupational Safety and Health Administration (OSHA). 2023. "29 CFR 1910.106 — Flammable Liquids." U.S. Department of Labor, Federal Register. https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.106.
  4. European Chemicals Agency (ECHA). 2024. "Annex VI to Regulation (EC) No 1272/2008 (CLP) — Harmonised Classification and Labelling." ECHA, Helsinki / Official Journal of the European Union. https://echa.europa.eu/regulations/clp/clp-classification.
  5. European Committee for Standardization (CEN). 2016. "EN 374-1:2016 — Protective gloves against dangerous chemicals and micro-organisms — Part 1: Terminology and performance requirements for chemical risks." CEN, Brussels. https://standards.cencenelec.eu/dyn/www/f?p=205:110:::::FSP_PROJECT,FSP_ORG_ID:38536,6080&cs=1B0DAA8B85DF42E4A2C70E5D71F0BFA32.
  6. European Committee for Standardization (CEN). 2001. "EN 166:2001 — Personal eye-protection — Specifications." CEN, Brussels. https://standards.cencenelec.eu/dyn/www/f?p=CEN:110:0::::FSP_PROJECT:6541&cs=1F1A4E0A78C4DB6A28DBE2E8C29D89DCF.
  7. European Committee for Standardization (CEN). 2009. "EN 14605:2005+A1:2009 — Protective clothing against liquid chemicals — Performance requirements for clothing with liquid-tight (Type 3) or spray-tight (Type 4) connections." CEN, Brussels. https://standards.cencenelec.eu/dyn/www/f?p=CEN:110:0::::FSP_PROJECT:21581&cs=1A04A2D3C7CC58E9E6CB58D55F7EBFB7E.
  8. National Institute for Occupational Safety and Health (NIOSH). 2017. "Recommendations for Chemical Protective Clothing: A Companion to the NIOSH Pocket Guide." U.S. Department of Health & Human Services / CDC. https://www.cdc.gov/niosh/ncpc/default.html.
  9. Occupational Safety and Health Administration (OSHA). 2011. "Personal Protective Equipment — General requirements." U.S. Department of Labor — 29 CFR 1910.132. https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.132.

📖 Books

  1. Hansen, Charles M. 2007. Hansen Solubility Parameters: A User's Handbook, 2nd ed.. Boca Raton, FL: CRC Press. https://www.routledge.com/Hansen-Solubility-Parameters-A-Users-Handbook/Hansen/p/book/9780849372483.
  2. Barton, Allan F. M. 1991. CRC Handbook of Solubility Parameters and Other Cohesion Parameters: 2nd ed.. Boca Raton, FL: CRC Press. https://www.routledge.com/CRC-Handbook-of-Solubility-Parameters-and-Other-Cohesion-Parameters/Barton/p/book/9780849301766.
  3. Connors, Kenneth A., Gordon L. Amidon, and Valentino J. Stella. 1986. Chemical Stability of Pharmaceuticals: A Handbook for Pharmacists, 2nd ed.. New York: Wiley. https://doi.org/10.1002/0471734683.
  4. Rumble, John R., ed. 2019. CRC Handbook of Chemistry and Physics: 100th Edition. Boca Raton, FL: CRC Press. https://hbcp.chemnetbase.com/.
  5. Urben, Peter G. 2017. Bretherick's Handbook of Reactive Chemical Hazards, 8th Edition. Academic Press / Elsevier, Oxford. https://www.sciencedirect.com/book/9780081010594.

📄 Scientific articles (peer-reviewed)

  1. Stefanis, Emmanuel, and Costas Panayiotou. 2008. "Prediction of Hansen Solubility Parameters with a New Group-Contribution Method." International Journal of Thermophysics 29: 568-585. https://doi.org/10.1007/s10765-008-0415-z.
  2. Stoll, Vincent S., and John S. Blanchard. 1990. "Buffers: Principles and Practice: In Methods in Enzymology, vol. 182." San Diego: Academic Press. https://doi.org/10.1016/0076-6879(90)82008-P.

🌐 Websites

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  3. ECHA. 2023. "Candidate List of Substances of Very High Concern for Authorisation." European Chemicals Agency. https://echa.europa.eu/candidate-list-table.
  4. European Parliament. 2008. "Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of Substances and Mixtures (CLP)." Official Journal of the European Union L 353: 1–1355.
  5. ECHA. 2017. "Guidance on the Compilation of Safety Data Sheets." Version 3.1. European Chemicals Agency. ECHA-17-G-01-EN. https://echa.europa.eu/documents/10162/23047722/sds_en.pdf.
  6. ECHA. 2022. "Restrictions Under REACH — Annex XVII." European Chemicals Agency. https://echa.europa.eu/substances-restricted-under-reach.
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  9. U.S. Occupational Safety and Health Administration (2024) — 29 CFR 1910.120 — Hazardous Waste Operations and Emergency Response (HAZWOPER) https://www.osha.gov/hazwoper.
  10. National Fire Protection Association (2018) — NFPA 472: Standard for Competence of Responders to Hazardous Materials/Weapons of Mass Destruction Incidents https://www.nfpa.org/codes-and-standards/nfpa-472.
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  12. U.S. National Institute for Occupational Safety and Health (2024) — NIOSH Pocket Guide to Chemical Hazards https://www.cdc.gov/niosh/npg/.
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