Clearsynth is a leading innovator in pharmaceutical reference standards, offering high-quality Reference Standards for L-cysteine, including both pharmacopeial and non-pharmacopeial impurities, metabolites, stable isotope products, and nitrosamines (N-NO products). Our L-cysteine impurity reference standards are invaluable for pharmaceutical research, supporting product development, ANDA and DMF submissions, quality control (QC), method validation, and stability studies. They also aid in identifying unknown impurities and assessing genotoxic potential.
Our L-cysteine-related products undergo thorough characterization and are supplied with detailed Certificates of Analysis (COA) and analytical data that meet regulatory requirements. All supplied products are re-tested at regular intervals to ensure ongoing quality and compliance.
Our L-cysteine-related products undergo thorough characterization and are supplied with detailed Certificates of Analysis (COA) and analytical data that meet regulatory requirements. All supplied products are re-tested at regular intervals to ensure ongoing quality and compliance.
L-cysteine Related Compounds
Stable Isotopes
| COMPOUND | CATEGORY | CAT. No. | CAS. No. | STOCK STATUS |
|---|---|---|---|---|
| (R,S)-N-Acetyl-S-(2-hydroxy-2-methyl-3-buten-1-yl)-L-cystein... | Stable Isotopes | CS-T-97063 | Not Available | Enquire |
| (R,S)-N-Acetyl-S-(2-hydroxy-3-methyl-3-buten-1-yl)-L-cystein... | Stable Isotopes | CS-T-94756 | Not Available | Enquire |
| cis-N-Acetyl-S-(4-hydroxy-2-buten-1-yl)-L-cysteine-d3 | Stable Isotopes | CS-T-94397 | Not Available | Enquire |
| D,L-Sulforaphane-d8 N-Acetyl-L-cysteine Sodium Salt | Stable Isotopes | CS-T-95530 | 334829-66-2(Unlabelled) | Enquire |
| DL-Cysteine-3,3-d2 | Stable Isotopes | CS-T-102501 | 124051-54-3 | Enquire |
| L-Homocysteine-3,3,4,4-d4 | Stable Isotopes | CS-T-102913 | 331665-12-4 | Enquire |
| N-(Acetyl-d3)-S-(2-carboxyethyl)-L-cysteine Bis(dicyclohexyl... | Stable Isotopes | CS-T-94749 | 51868-61-2(Unlabelled) | Enquire |
| N-(Acetyl-d3)-S-(2-carboxypropyl)-L-cysteine Ethyl Ester (Mi... | Stable Isotopes | CS-T-97065 | Not Available | Enquire |
| N-Acetyl-d3-S-(2-ethoxycarbonylethyl-1-methyl)-L-cysteine, D... | Stable Isotopes | CS-T-97064 | 33297-48-2 (Unlabelled) | Enquire |
| N-Acetyl-L-Cysteine-d3 | Stable Isotopes | CS-T-47181 | 131685-11-5 | In Stock |
| N-Acetyl-S-(1,2-dichloroethenyl)-L-cysteine-13C,d3 | Stable Isotopes | CS-T-94344 | Not Available | Enquire |
| N-Acetyl-S-(2-carbamoylethyl-d4)-L-cysteine | Stable Isotopes | CS-O-15397 | 81690-92-8 (Unlabeled) | Enquire |
| N-Acetyl-S-(2-carboxyethyl)-L-cysteine-13C3 Bis(dicyclohexyl... | Stable Isotopes | CS-T-97073 | Not Available | Enquire |
| N-Acetyl-S-(2-hydroxy-1-phenylethyl)-L-cysteine-13C6 + N-Ace... | Stable Isotopes | CS-T-94401 | 69278-53-1 + 14510-10-2- for unlabelled | Enquire |
| N-Acetyl-S-(2-hydroxy-1-phenylethyl)-L-cysteine-d3 Sodium Sa... | Stable Isotopes | CS-T-94757 | 69278-53-1 + 14510-10-2(Unlabelled) | Enquire |
| N-Acetyl-S-(2-hydroxy-3-but-3-en-1-yl)-L-Cysteine 1,2,3-13C3... | Stable Isotopes | CS-T-97060 | Not Available | Enquire |
| N-Acetyl-S-(2-hydroxy-3-propionamide)-L-cysteine-d3 Dicycloh... | Stable Isotopes | CS-T-94322 | 137698-08-9(unlabelled) | Enquire |
| N-Acetyl-S-(3,4-dihydroxybutyl)-L-cysteine-13C4 (Mixture of ... | Stable Isotopes | CS-T-103125 | 144889-50-9(Unlabelled) | Enquire |
| N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine-D3 | Stable Isotopes | CS-T-94755 | 100496-03-5(Unlabelled) | Enquire |
| N-Acetyl-S-(4-hydroxy-2-buten-1-yl)-L-cysteine-d3 | Stable Isotopes | CS-T-94372 | 159092-65-6-unlabelled | Enquire |
| N-Acetyl-S-(4-hydroxy-2-Methyl-2-trans-buten-1-yl)-L-cystein... | Stable Isotopes | CS-T-94394 | 2714414-67-0 | Enquire |
| N-Acetyl-S-(4-hydroxy-3-methyl-2-trans-buten-1-yl)-L-cystein... | Stable Isotopes | CS-T-94373 | Not Available | Enquire |
| N-Acetyl-S-(carbamoylethyl)-L-cysteine-13C3 | Stable Isotopes | CS-T-97066 | Not Available | Enquire |
| N-Acetyl-S-(methylphenyl-13C6)-L-cysteine | Stable Isotopes | CS-T-95633 | 19542-77-9 (Unlabelled | Enquire |
| N-Acetyl-S-(phenyl-13C6)-L-cysteine | Stable Isotopes | CS-T-95637 | 4775-80-8 Unlabelled | Enquire |
| N-Acetyl-S-[2-hydroxy-1-(3-pyridinyl)ethyl]-L-cysteine-D3 | Stable Isotopes | CS-T-97841 | Not Available | Enquire |
| N-Acetyl-S-[2-hydroxy-2-(3-pyridinyl)ethyl]-L-cysteine-D3 | Stable Isotopes | CS-T-97842 | Not Available | Enquire |
| N-Acetyl-S-benzyl-2,3,4,5,6-d5-DL-cysteine | Stable Isotopes | CS-T-95198 | 19538-71-7(Unlabeled) | Enquire |
| N-Acetyl-S-phenyl-d5-DL-cysteine | Stable Isotopes | CS-T-94761 | 20640-68-0(Unlabelled) | Enquire |
| N-Acetyl-S-phenyl-DL-cysteine-3,3-d2 | Stable Isotopes | CS-T-94741 | 20640-68-0(Unlabelled) | Enquire |
| S-(3-Hydroxypropyl)-L-cysteine-d6 | Stable Isotopes | CS-T-96928 | Not Available | Enquire |
| S-Phenyl-D5-L-cysteine | Stable Isotopes | CS-T-94378 | 34317-61-8(Unlabelled) | Enquire |
| S-Phenyl-DL-cysteine-3,3-d2 | Stable Isotopes | CS-T-94742 | 5437-52-5(Unlabelled) | Enquire |
| (R,S)-N-Acetyl-S-[1-(hydroxymethyl)-2-propenyl)-L-cysteine-d... | Stable Isotopes | CS-T-94382 | Not Available | Enquire |
| (R,S)-N-Acetyl-S-[1-(hydroxymethyl)-2-propenyl)-L-cysteine-d... | Stable Isotopes | CS-T-95338 | Not Available | Enquire |
| D,L-Sulforaphane-d8 N-Acetyl-L-cysteine | Stable Isotopes | CS-T-61520 | 1354064-85-9 | Enquire |
| DL-Cysteine-3-13C | Stable Isotopes | CS-T-73316 | 150146-94-4 | Enquire |
| L-CYSTEINE 13C3 | Stable Isotopes | CS-R-00043 | 202114-66-7 | Enquire |
| L-CYSTEINE 15N | Stable Isotopes | CS-R-00045 | 204523-09-1 | Enquire |
| L-CYSTEINE D3 | Stable Isotopes | CS-R-00046 | 214782-32-8 | Enquire |
| L-CYSTEINE, S-METHYL D3 | Stable Isotopes | CS-R-00052 | 1331907-56-2 | Enquire |
| L-Cysteine-1-13C | Stable Isotopes | CS-T-73586 | 224054-24-4 | Enquire |
| L-Cysteine-N,N-d2 | Stable Isotopes | CS-R-00049 | 4331-27-5 | Enquire |
| N-(Acetyl-d3)-S-[4-(2-pyridinyl)benzyl]-L-cysteine | Stable Isotopes | CS-T-64277 | 1795785-71-5 | Enquire |
| N-(Acetyl-d3)-S-allyl-L-cysteine | Stable Isotopes | CS-T-47075 | 1331907-55-1 | Enquire |
| N-(Acetyl-d3)-S-benzyl-L-cysteine | Stable Isotopes | CS-T-47121 | 201404-15-1 | Enquire |
| N-Acetyl-d3-S-(3-hydroxypropyl-1-methyl)-L-cysteine Dicycloh... | Stable Isotopes | CS-T-64522 | 1240483-48-0 | Enquire |
| N-Acetyl-L-cysteine-13C3,15N | Stable Isotopes | CS-T-95634 | 2300155-89-7 | Enquire |
| N-Acetyl-S-(1-cyano-2-hydroxyethyl)-L-cysteine-d3 Dicyclohex... | Stable Isotopes | CS-T-94374 | 1356017-48-5 | Enquire |
| N-Acetyl-S-(2,2-dichloroethenyl)-L-cysteine-13C,d3 | Stable Isotopes | CS-T-64461 | 1795787-09-5 | Enquire |
| N-Acetyl-S-(2,5-dimethylbenzene)-L-cysteine-d3 | Stable Isotopes | CS-T-64506 | 1331909-07-9 | Enquire |
| N-Acetyl-S-(2-carboxypropyl)-L-cysteine-d3 Dicyclohexylammon... | Stable Isotopes | CS-T-94364 | 73614-35-4-unlabelled free acid | Enquire |
| N-Acetyl-S-(2-cyanocarboxyethyl)-L-cysteine-d3 Bis(dicyclohe... | Stable Isotopes | CS-T-64380 | 1356848-13-9 | Enquire |
| N-Acetyl-S-(2-ethoxycarbonylethyl-1-methyl)-L-cysteine-d3 | Stable Isotopes | CS-T-64564 | 45215-04-1 | Enquire |
| N-acetyl-S-(2-hydroxy-1-phenylethyl)-L-cysteine-13C6 | Stable Isotopes | CS-O-37864 | 69278-53-1 (Unlabeled) | Enquire |
| N-Acetyl-S-(2-hydroxyethyl-d4)-L-cysteine Dicyclohexylamine ... | Stable Isotopes | CS-T-47283 | 1331894-57-5 | Enquire |
| N-Acetyl-S-(3,4-dihydroxybutyl)-L-cysteine-d7 (Mixture of Di... | Stable Isotopes | CS-T-64288 | 1240398-27-9 | Enquire |
| N-Acetyl-S-(3,4-dimethylbenzene)-L-cysteine-d3 | Stable Isotopes | CS-T-64416 | 1331892-61-5 | Enquire |
| N-Acetyl-S-(3-carboxy-2-propyl)-L-cysteine-d3 Disodium Salt | Stable Isotopes | CS-T-47168 | 1356933-73-7 | Enquire |
| N-Acetyl-S-(propyl-d7)-L-cysteine | Stable Isotopes | CS-T-64321 | 1331909-69-3 | Enquire |
| N-Acetyl-S-(trichlorovinyl)-L-cysteine-d3 | Stable Isotopes | CS-T-65072 | 1346616-95-2 | Enquire |
| N-Acetyl-S-ethyl-L-cysteine-d5 | Stable Isotopes | CS-T-64396 | 1279033-91-8 | Enquire |
| N-Acetyl-S-methyl-L-cysteine-d3 | Stable Isotopes | CS-T-64397 | 1279039-06-3 | Enquire |
| S-(2-Hydroxyethyl-d4)-L-cysteine | Stable Isotopes | CS-T-78504 | 1331903-64-0 | Enquire |
| S-(N-Methyl-d3-carbamoyl)-L-cysteine | Stable Isotopes | CS-T-82671 | 127633-26-5 | Enquire |
| S-Trityl-N-Fomc_L-Cysteine-34S | Stable Isotopes | CS-P-08202 | 103213-32-7 (Unlabeled) | Enquire |
API
| COMPOUND | CATEGORY | CAT. No. | CAS. No. | STOCK STATUS |
|---|---|---|---|---|
| DL-Cysteine | API | CS-T-14249 | 3374-22-9 | Enquire |
Metabolite
| COMPOUND | CATEGORY | CAT. No. | CAS. No. | STOCK STATUS |
|---|---|---|---|---|
| N-Acetyl-S-(3-hydroxypropyl)cysteine | Metabolite | CS-T-47291 | 23127-40-4 | In Stock |
| N-Acetyl-S-(N-methylcarbamoyl)-L-cysteine | Metabolite | CS-T-00946 | 103974-29-4 | Enquire |
| N-Acetyl-S-(trichlorovinyl)-L-cysteine | Metabolite | CS-T-01219 | 111348-61-9 | In Stock |
| N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine | Metabolite | CS-TA-01850 | 100496-03-5 | Enquire |
Impurity
| COMPOUND | CATEGORY | CAT. No. | CAS. No. | STOCK STATUS |
|---|---|---|---|---|
| L-Lysine S-(Carboxymethyl)-L-Cysteine | Impurity | CS-P-01557 | 49673-81-6 | In Stock |
| N-Acetyl-S-(2-carboxyethyl)-L-cysteine Bis(dicyclohexylamine... | Impurity | CS-BI-00015 | 201666-27-5 | In Stock |
| N-Acetyl-S-Phenyl-L-Cysteine | Impurity | CS-O-02393 | 4775-80-8 | In Stock |
| 2-Ethoxyethyl-L-cysteine | Impurity | CS-T-22363 | 885457-17-0 | Enquire |
| Boc-L-cysteine | Impurity | CS-T-07414 | 20887-95-0 | Enquire |
| Boc-S-t-butyl-L-cysteine | Impurity | CS-M-29633 | 56976-06-8 | Enquire |
| D,L-Sulforaphane N-Acetyl-L-cysteine | Impurity | CS-T-61519 | 334829-66-2 | Enquire |
| Di-Boc-S-(2-aminoethyl)-L-cysteine | Impurity | CS-M-29635 | 130622-07-0 | Enquire |
| D-Ribose-L-cysteine | Impurity | CS-T-61144 | 232617-15-1 | Enquire |
| Ethacrynic Acid L-Cysteine Adduct | Impurity | CS-T-54200 | 51246-37-8 | Enquire |
| L-Cysteine-D-penicillamine Disulfide | Impurity | CS-T-51548 | 18840-45-4 | Enquire |
| N-[2-(1-Naphthalenyl)acetyl]-L-cysteine | Impurity | CS-O-39875 | 32668-00-1 | Enquire |
| N-Acetyl-S-(1,2-dichloroethenyl)-L-cysteine | Impurity | CS-T-47191 | 2148-31-4 | Enquire |
| N-Acetyl-S-(2,2-dichloroethenyl)-L-cysteine | Impurity | CS-T-46895 | 126543-43-9 | Enquire |
| N-Acetyl-S-(2-cyanocarboxyethyl)-L-cysteine Bis(dicyclohexyl... | Impurity | CS-T-64569 | 1356930-50-1 | Enquire |
| N-Acetyl-S-(3,4-dihydroxybutyl)-L-cysteine | Impurity | CS-T-47215 | 144889-50-9 | Enquire |
| N-Acetyl-S-propyl-L-cysteine | Impurity | CS-T-47070 | 14402-54-1 | Enquire |
| N-Boc-L-cysteine Methanethiosulfonate | Impurity | CS-T-07504 | 1043867-42-0 | Enquire |
| N-Boc-S-benzyl-L-cysteine | Impurity | CS-T-07466 | 5068-28-0 | Enquire |
| N-Boc-S-benzyl-L-cysteine Methyl Ester | Impurity | CS-T-07467 | 55478-08-5 | Enquire |
| S-(2,4-Dimethylbenzene)-D,L-cysteine | Impurity | CS-T-19809 | 1357350-92-5 | Enquire |
| S-(2,5-Dimethylbenzene)-L-cysteine | Impurity | CS-T-19807 | 1331895-23-8 | Enquire |
| S-(3,4-Dimethylbenzene)-L-cysteine | Impurity | CS-T-19808 | 1331904-81-4 | Enquire |
| S-[N-(3-Phenylpropyl)(thiocarbamoyl)]-L-cysteine | Impurity | CS-T-60497 | 137915-13-0 | Enquire |
| S-Benzyl-L-cysteine Sulfone | Impurity | CS-T-05526 | 25644-88-6 | Enquire |
| S-Benzyl-N-Stearoyl-L-cysteine | Impurity | CS-T-06305 | 40379-70-2 | Enquire |
| S-Methyl-L-Cysteine-S-oxide | Impurity | CS-P-07570 | 6853-87-8 | Enquire |
Fine Chemicals
| COMPOUND | CATEGORY | CAT. No. | CAS. No. | STOCK STATUS |
|---|---|---|---|---|
| L-Cysteine Hydrochloride | Fine Chemicals | CS-O-30635 | 52-89-1 | In Stock |
| N-Acetyl-S-(N-allylthiocarbamoyl)-L-cysteine | Fine Chemicals | CS-ED-42224 | 87321-45-7 | Enquire |
| S-Allyl-L-cysteine | Fine Chemicals | CS-O-30769 | 21593-77-1 | In Stock |
| (R,S)-N-acetyl-S-[1-(hydroxymethyl)-2-propenyl-L-cysteine] | Fine Chemicals | CS-O-37862 | Not Available | Enquire |
| captopril-cysteine | Fine Chemicals | CS-O-33583 | 75479-46-8 | Enquire |
Building Blocks
| COMPOUND | CATEGORY | CAT. No. | CAS. No. | STOCK STATUS |
|---|---|---|---|---|
| Fmoc-L-Cys-(Acm)-OH | Building Blocks | CS-U-00019 | 86060-81-3 | In Stock |
| L-Cysteine hydrochloride monohydrate | Building Blocks | CS-AX-05984 | 7048-04-6 | In Stock |
| N-Acetyl-S-benzyl-L-Cysteine | Building Blocks | CS-O-02001 | 19542-77-9 | In Stock |
| S-(3-Carboxypropyl)-L-cysteine | Building Blocks | CS-T-50364 | 30845-11-5 | In Stock |
| S-Benzyl-L-cysteine | Building Blocks | CO-K-00002 | 3054-01-1 | Enquire |
| S-Methyl-L-cysteine | Building Blocks | CS-T-82011 | 1187-84-4 | In Stock |
| S-Trityl-L-cysteine | Building Blocks | CS-T-45935 | 2799-07-7 | In Stock |
| γ-L-Glutamyl-L-cysteine | Building Blocks | CS-N-00388 | 636-58-8 | Enquire |
| 4-Azido-2,3,5,6-tetrafluorobenzamido-L-cysteine Methanethios... | Building Blocks | CS-T-04635 | 352000-06-7 | Enquire |
| Boc-S-[2-(4-pyridyl)ethyl]-L-cysteine | Building Blocks | CS-M-29622 | 151545-15-2 | Enquire |
| Boc-S-diphenylmethyl-L-cysteine | Building Blocks | CS-M-29629 | 21947-97-7 | Enquire |
| Boc-S-ethyl-L-cysteine | Building Blocks | CS-M-29630 | 16947-82-3 | Enquire |
| Boc-S-methyl-L-cysteine | Building Blocks | CS-M-29631 | 16947-80-1 | Enquire |
| Fmoc-S-4-methoxytrityl-L-cysteine | Building Blocks | CS-DV-03587 | 177582-21-7 | Enquire |
| Fmoc-S-benzyl-L-cysteine | Building Blocks | CS-M-29646 | 53298-33-2 | Enquire |
| Fmoc-S-ethyl-L-cysteine | Building Blocks | CS-M-29650 | 200354-34-3 | Enquire |
| Fmoc-S-methyl-L-cysteine | Building Blocks | CS-M-29651 | 138021-87-1 | Enquire |
| Fmoc-S-t-butyl-L-cysteine | Building Blocks | CS-M-29653 | 67436-13-9 | Enquire |
| N-Acetyl-L-cysteine Allyl Ester | Building Blocks | CS-T-47182 | 145452-04-6 | Enquire |
| N-Acetyl-L-cysteine methyl ester | Building Blocks | CS-O-13146 | 7652-46-2 | Enquire |
| N-Acetyl-S-(2,5-dimethylbenzene)-L-cysteine | Building Blocks | CS-T-47224 | 581076-70-2 | Enquire |
| N-Acetyl-S-(2-ethoxycarbonylethyl-1-methyl)-L-cysteine, Dicy... | Building Blocks | CS-T-47225 | 33297-48-2 | Enquire |
| N-Acetyl-S-(3,4-dimethylbenzene)-L-cysteine | Building Blocks | CS-T-47221 | 581076-72-4 | Enquire |
| N-Acetyl-S-allyl-L-cysteine | Building Blocks | CS-T-64549 | 23127-41-5 | Enquire |
| N-Acetyl-S-ethyl-L-cysteine | Building Blocks | CS-T-47232 | 31386-36-4 | Enquire |
| N-Carbamoyl-L-cysteine | Building Blocks | CS-T-10201 | 24583-23-1 | Enquire |
| N-Methyl-L-cysteine Hydrochloride | Building Blocks | CS-T-33503 | 14344-46-8 | Enquire |
| N-Propionyl-L-cysteine | Building Blocks | CS-T-40678 | 2885-79-2 | Enquire |
| N-Stearoyl-L-cysteine | Building Blocks | CS-T-42661 | 67603-50-3 | Enquire |
| S-(2-Aminoethyl)-l-cysteine, HCl | Building Blocks | CS-T-65873 | 4099-35-8 | Enquire |
| S-(2-Carboxyethyl)-L-cysteine | Building Blocks | CS-T-10401 | 100429-59-2 | Enquire |
| S-[N-Benzyl(thiocarbamoyl)]-L-cysteine | Building Blocks | CS-T-49059 | 35446-36-7 | Enquire |
| S-9-Fluorenylmethyl-L-cysteine Hydrochloride | Building Blocks | CS-T-74377 | 84888-34-6 | Enquire |
| S-Cyanoethyl-L-cysteine | Building Blocks | CS-T-13621 | 3958-13-2 | Enquire |
| S-Phenyl-L-cysteine | Building Blocks | CS-T-39419-5GM | 34317-61-8 | Enquire |
| S-Phenyl-L-cysteine | Building Blocks | CS-T-39419 | 34317-61-8 | Enquire |
| S-Phenyl-L-cysteine-N-(3-aminophenyl)amide | Building Blocks | CS-T-39422 | 1331902-93-2 | Enquire |