Impurity Standards

Impurity Standards:
Ensuring Quality and Safety in the Pharmaceutical Industry

The pharmaceutical industry is constantly striving to provide safe and effective medications for patients around the world. To achieve this goal, it's important to ensure that drugs are free from harmful impurities that could potentially cause adverse effects. This is where impurity standards come into play.

What are impurity standards?

Impurity standards are guidelines that establish acceptable levels of impurities in pharmaceuticals. These impurities can come from a variety of sources, including starting materials, reagents, and the manufacturing process itself. Impurity standards are set by regulatory agencies such as the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).

Why are impurity standards important?

Impurity standards are crucial for ensuring the safety and efficacy of pharmaceuticals. Impurities can have a variety of negative effects on drug products, including reducing their potency, causing toxicity, and decreasing their shelf life. In some cases, impurities can even lead to serious adverse events in patients. By setting acceptable levels of impurities, impurity standards help to ensure that pharmaceuticals are safe and effective for their intended use.

How are impurity standards established?

Impurity standards are established through a variety of methods. One common approach is to use analytical techniques such as high-performance liquid chromatography (HPLC) and gas chromatography (GC) to identify and quantify impurities in pharmaceuticals. Once impurities are identified, impurity standards can be established based on their potential for harm and their concentration in the drug product.

Who is responsible for enforcing impurity standards?

Regulatory agencies such as the FDA and EMA are responsible for enforcing impurity standards. These agencies conduct inspections of pharmaceutical manufacturing facilities to ensure that drugs are being produced in compliance with impurity standards. In addition, pharmaceutical companies are required to perform their own testing to ensure that their products meet impurity standards before they can be sold to consumers.

Conclusion Impurity standards are a critical component of ensuring the safety and efficacy of pharmaceuticals. By establishing acceptable levels of impurities, regulatory agencies help to ensure that drugs are free from harmful contaminants that could potentially cause harm to patients. Pharmaceutical companies must comply with these standards through rigorous testing and quality control measures to ensure that their products meet the highest levels of safety and efficacy.

Recently Searched Impurities

Zoledronic acid impurity B inner salt

CAS No.: 1627731-61-6
Molecular Formula: C₇H₁₆N₂O₁₄P₄
Molecular Weight: 476.10
CAT No.: CS-O-16034
Stock: In-stock

Nor Neostigmine

CAS No.: 16088-19-0
Molecular Formula: C₁₁H₁₆N₂O₂
Molecular Weight: 208.26
CAT No.: CS-T-37592
Stock: In-stock

Zuclopenthixol Deconate 2 HCl

CAS No.: 1448876-93-4
Molecular Formula: C₃₂H₄₅Cl₃N₂O₂S
Molecular Weight: 628.14
CAT No.: CS-O-14594
Stock: In-stock

Losartan Azide impurity

CAS No.: 727718-93-6
Molecular Formula: C₂₂H₂₂ClN₉
Molecular Weight: 447.92
CAT No.: CS-O-35717
Stock: In-stock

Tenofovir Mono-POC methyl ester

CAS No.: 1246812-16-7
Molecular Formula: C₁₅H₂₄N₅O₇P
Molecular Weight: 417.35
CAT No.: CS-T-58933
Stock: In-stock

Naproxen Impurity F

CAS No.: 31220-35-6
Molecular Formula: C₁₆H₁₈O₃
Molecular Weight: 258.31
CAT No.: CS-DH-00018
Stock: In-stock

Orphenadrine citrate USP Impurity B

CAS No.: 93940-17-1
Molecular Formula: C₂₀H₂₈ClNO
Molecular Weight: 333.90
CAT No.: CS-EN-00075
Stock: In-stock

Methyl 12-Ketostearate

CAS No.: 2380-27-0
Molecular Formula: C₁₉H₃₆O₃
Molecular Weight: 312.49
CAT No.: CS-T-34172
Stock: In-stock

Ginsenoside Rg1

CAS No.: 22427-39-0
Molecular Formula: C₄₂H₇₂O₁₄
Molecular Weight: 801.01
CAT No.: CS-E-00938
Stock: In-stock

Amlodipine Azido Impurity

CAS No.: 88150-46-3
Molecular Formula: C₂₀H₂₃ClN₄O₅
Molecular Weight: 434.87
CAT No.: CS-T-04601
Stock: In-stock

Remdesivir Impurity 2

CAS No.: Not Available
Molecular Formula: C₁₉H₁₉N₅O₄
Molecular Weight: 381.39
CAT No.: CS-P-08450
Stock: In-stock

Rapamycin 31,42-Bis(2,2,5-trimethyl-1,3-dioxane-5-carboxylate)

CAS No.: 1401284-72-7
Molecular Formula: C₆₇H₁₀₃NO₁₉
Molecular Weight: 1226.53
CAT No.: CS-T-85960
Stock: In-stock

Miconazole EP impurity I

CAS No.: 47363-37-1
Molecular Formula: C₁₈H₁₅Cl₃N₂O
Molecular Weight: 381.68
CAT No.: CS-O-07927
Stock: In-stock

Misoprostol EP Impurity A

CAS No.: 1788085-78-8
Molecular Formula: C₂₂H₃₈O₅
Molecular Weight: 382.53
CAT No.: CS-EO-00153
Stock: In-stock

Silodosin (S-ISOMER)

CAS No.: 2182279-45-2
Molecular Formula: C₂₅H₃₂F₃N₃O₄
Molecular Weight: 495.53
CAT No.: CS-O-14411
Stock: In-stock

Rabeprazole USP Related Compound F

CAS No.: 168167-42-8
Molecular Formula: C₁₄H₁₂ClN₃OS
Molecular Weight: 305.78
CAT No.: CS-T-16126
Stock: In-stock

Neostigmine methyl sulphate

CAS No.: 51-60-5
Molecular Formula: C13H22N2O6S
Molecular Weight: 334.39
CAT No.: CS-O-30696
Stock: In-stock

Glycyl-histidyl-lysine, monocopper salt

CAS No.: 89030-95-5
Molecular Formula: C14H23CuN6O4
Molecular Weight: 402.91
CAT No.: CS-O-11113
Stock: In-stock

Dimethindene Maleate

CAS No.: 3614-69-5
Molecular Formula: C₂₄H₂₈N₂O₄
Molecular Weight: 408.49
CAT No.: CS-T-53320
Stock: In-stock

Empagliflozin Diol impurity (S-Isomer)

CAS No.: 2452301-18-5
Molecular Formula: C23H29ClO8
Molecular Weight: 468.9
CAT No.: CS-EO-02027
Stock: In-stock

Cefadroxil impurity A

CAS No.: 22818-40-2
Molecular Formula: C₈H₉NO₃
Molecular Weight: 167.16
CAT No.: CS-O-03630
Stock: In-stock


CAS No.: 992-65-4
Molecular Formula: C₃₇H₆₇NO₁₄
Molecular Weight: 749.92
CAT No.: CS-CM-00085
Stock: In-stock

Cinnarizine EP Impurity E

CAS No.: 216581-01-0
Molecular Formula: C₃₀H₃₀N₂
Molecular Weight: 418.57
CAT No.: CS-O-07637
Stock: In-stock

Rabeprazole Impurity G

CAS No.: 935260-92-7
Molecular Formula: C29H36N4O5S
Molecular Weight: 552.68
CAT No.: CS-O-08050
Stock: In-stock

Vildagliptin Impurity B

CAS No.: 1036959-23-5
Molecular Formula: C₂₄H₃₃N₅O₃
Molecular Weight: 439.55
CAT No.: CS-AQ-00079
Stock: In-stock

Mirabegron Impurity 4

CAS No.: 1684452-83-2
Molecular Formula: C26H28N6O3S2
Molecular Weight: 536.7
CAT No.: CS-O-13206
Stock: In-stock

Aciclovir Impurity J

CAS No.: 166762-90-9
Molecular Formula: C₁₄H₁₆N₁₀O₄
Molecular Weight: 388.34
CAT No.: CS-J-00011
Stock: In-stock

Thioridazine EP Impurity E

CAS No.: 14759-06-9
Molecular Formula: C21H26N2O2S2
Molecular Weight: 402.57
CAT No.: CS-O-08294
Stock: In-stock

Paracetamol EP Impurity J

CAS No.: 539-03-7
Molecular Formula: C₈H₈ClNO
Molecular Weight: 169.61
CAT No.: CS-O-31142
Stock: In-stock

Deschloro-1,2-dihydro-2-oxo Clomiphene Hydrochloride Salt

CAS No.: 5635-70-1
Molecular Formula: C₂₆H₃₀ClNO₂
Molecular Weight: 423.98
CAT No.: CS-T-52104
Stock: In-stock

Palbociclib Impurity 3

CAS No.: 1651214-74-2
Molecular Formula: C₂₉H₃₇N₇O₄
Molecular Weight: 547.65
CAT No.: CS-P-01928
Stock: In-stock


CAS No.: 75883-07-7
Molecular Formula: C₂₅H₃₃FO₆
Molecular Weight: 448.52
CAT No.: CS-O-30544
Stock: In-stock

Empagliflozin Acetyl impurity

CAS No.: 1079083-63-8
Molecular Formula: C₂₇H₂₉ClO₁₀
Molecular Weight: 548.97
CAT No.: CS-EO-00244
Stock: In-stock

rac Guaifenesin Cyclic Carbonate

CAS No.: 2049-21-0
Molecular Formula: C₁₁H₁₂O₅
Molecular Weight: 224.21
CAT No.: CS-T-55459
Stock: In-stock

Omeprazole EP Impurity G

CAS No.: 125656-83-9
Molecular Formula: C₁₆H₁₃N₃O₂S
Molecular Weight: 311.36
CAT No.: CS-O-15599
Stock: In-stock

Enzalutamide Impurity 8

CAS No.: 1802242-43-8
Molecular Formula: C₂₁H₁₅F₄N₃O₃S
Molecular Weight: 465.42
CAT No.: CS-O-14636
Stock: In-stock


CAS No.: 1207995-62-7
Molecular Formula: C₁₈H₃₈N₂O
Molecular Weight: 298.51
CAT No.: CS-T-59627
Stock: In-stock

Amlodipine EP Impurity F

CAS No.: 140171-66-0
Molecular Formula: C₁₉H₂₃ClN₂O₅
Molecular Weight: 394.85
CAT No.: CS-O-07178
Stock: In-stock

Cinacalcet Impurity A

CAS No.: 3886-70-2
Molecular Formula: C₁₂H₁₄ClN
Molecular Weight: 207.70
CAT No.: CS-O-07624
Stock: In-stock

N-Desmethyl Prochlorperazine Dimaleate

CAS No.: 13500-92-0
Molecular Formula: C₂₇H₃₀ClN₃O₈S
Molecular Weight: 592.06
CAT No.: CS-T-52251
Stock: In-stock

Fexofenadine EP Impurity A

CAS No.: 76811-98-8
Molecular Formula: C₃₂H₃₇NO₄
Molecular Weight: 499.64
CAT No.: CS-O-03405
Stock: In-stock

Mupirocin calcium EP impurity F sodium salt

CAS No.: 167842-64-0 (Free Acid)
Molecular Formula: C₂₄H₃₉NaO₉
Molecular Weight: 494.55
CAT No.: CS-O-16001
Stock: In-stock

Melphalan impurity B Di HCl salt

CAS No.: 1270153-04-2
Molecular Formula: C₁₃H₂₀Cl₂N₂O₃
Molecular Weight: 323.22
CAT No.: CS-O-13766
Stock: In-stock

Diethyl L-(+)-Tartrate

CAS No.: 87-91-2
Molecular Formula: C8H14O6
Molecular Weight: 206.19
CAT No.: CS-T-18273
Stock: In-stock

Pramipexole impurity C(Mixture of isomers)

CAS No.: 1973461-14-1
Molecular Formula: C20H32N6S2
Molecular Weight: 420.6
CAT No.: CS-O-14087
Stock: In-stock

Dorzolamide Impurity 4 (mixture of diastereomers)

CAS No.: --
Molecular Formula: C₂₀H₂₉N₃O₈S₆
Molecular Weight: 631.85
CAT No.: CS-O-16392
Stock: In-stock

Fexofenadine Related Compound B

CAS No.: 479035-75-1 (Freebase)
Molecular Formula: C₃₂H₄₂ClNO₅
Molecular Weight: 556.13
CAT No.: CS-O-38699
Stock: In-stock


CAS No.: 3627-51-8
Molecular Formula: C₂₃H₂₇NO₄
Molecular Weight: 381.47
CAT No.: CS-P-01796
Stock: In-stock

Aminoundecanoic acid

CAS No.: 2432-99-7
Molecular Formula: C11H23NO2
Molecular Weight: 201.31
CAT No.: CS-O-00935
Stock: In-stock

Enalapril EP Impurity C

CAS No.: 84680-54-6
Molecular Formula: C₁₈H₂₄N₂O₅·2H₂O
Molecular Weight: 384.43
CAT No.: CS-O-13801
Stock: In-stock


CAS No.: 109425-51-6
Molecular Formula: C₄₀H₃₃N₃O₄
Molecular Weight: 619.79
CAT No.: CS-U-00022
Stock: In-stock

N-Nitroso Flupirtine

CAS No.: --
Molecular Formula: C15H16FN5O3
Molecular Weight: 333.3
CAT No.: CS-EO-01242
Stock: In-stock

Enalapril EP impurity A (mixture of diastereomers)

CAS No.: --
Molecular Formula: C₂₀H₂₈N₂O₅
Molecular Weight: 376.45
CAT No.: CS-O-32598
Stock: In-stock

N-Nitroso N-Desmethyl Zolmitriptan

CAS No.: --
Molecular Formula: C₁₅H₁₈N₄O₃
Molecular Weight: 302.33
CAT No.: CS-EO-01161
Stock: In-stock

Chlorthalidone EP Impurity B

CAS No.: 5270-74-6
Molecular Formula: C14H10ClNO5S
Molecular Weight: 339.7
CAT No.: CS-O-03413
Stock: In-stock

Ebastine EP Impurity D

CAS No.: 97928-18-2
Molecular Formula: C₁₉H₂₉NO₂
Molecular Weight: 303.44
CAT No.: CS-T-09280
Stock: In-stock

Thioridazine EP Impurity A

CAS No.: 100574-22-9
Molecular Formula: C21H26N2O4S2
Molecular Weight: 434.6
CAT No.: CS-EO-00405
Stock: In-stock

Diethyl Amlodipine besylate salt impurity

CAS No.: --
Molecular Formula: C27H33ClN2O8S
Molecular Weight: 581.08
CAT No.: CS-O-16051
Stock: In-stock


CAS No.: 76498-29-8
Molecular Formula: C₂₁H₃₆O₅
Molecular Weight: 368.51
CAT No.: CS-T-71446
Stock: In-stock

Canagliflozin impurity C

CAS No.: 1030825-20-7
Molecular Formula: C₁₈H₁₄BrFS
Molecular Weight: 361.27
CAT No.: CS-AQ-00192
Stock: In-stock


CAS No.: 52691-24-4
Molecular Formula: C6H14Cl2N2Pt
Molecular Weight: 380.18
CAT No.: CS-O-14088
Stock: In-stock

Erdosteine Thioacid Disodium Salt

CAS No.: 254884-18-9
Molecular Formula: C₈H₁₁NNa₂O₅S₂
Molecular Weight: 311.29
CAT No.: CS-T-21900
Stock: In-stock

Isobutyl 2,2-Dimethyl-5-(2,5-xylyloxy) Valerate

CAS No.: 149105-26-0
Molecular Formula: C₁₉H₃₀O₃
Molecular Weight: 306.44
CAT No.: CS-O-31887
Stock: In-stock

Amiodarone EP Impurity D

CAS No.: 1951-26-4
Molecular Formula: C₁₉H₁₆I₂O₃
Molecular Weight: 546.14
CAT No.: CS-O-07161
Stock: In-stock

N-Nitroso Mirabegron Impurity 6

CAS No.: --
Molecular Formula: C₁₆H₁₉N₃O₂
Molecular Weight: 285.34
CAT No.: CS-O-44033
Stock: In-stock

Zolpidem USP related compound C

CAS No.: 349122-64-1
Molecular Formula: C₁₄H₁₄N₂O
Molecular Weight: 226.27
CAT No.: CS-O-05543
Stock: In-stock

N-nitroso (S) Tamsulosin

CAS No.: --
Molecular Formula: C₂₀H₂₇N₃O₆S
Molecular Weight: 437.51
CAT No.: CS-O-47022
Stock: In-stock

Mixture of Lactose Conjugates Impurity 2 & Pregabalin Impurity 12

CAS No.: --
Molecular Formula: C₄₀H₇₀N₂O₂₂
Molecular Weight: 930.98
CAT No.: CS-O-36618
Stock: In-stock

Deschloro Vemurafenib

CAS No.: 918504-63-9
Molecular Formula: C₂₃H₁₉F₂N₃O₃S
Molecular Weight: 455.48
CAT No.: CS-O-10696
Stock: In-stock

Trimethoxy Dobutamine Hydrochloride

CAS No.: 51062-14-7
Molecular Formula: C₂₁H₃₀ClNO₃
Molecular Weight: 379.92
CAT No.: CS-T-62425
Stock: In-stock

Acetazolamide EP Impurity B

CAS No.: 5393-55-5
Molecular Formula: C4H5N3OS
Molecular Weight: 143.17
CAT No.: CS-O-07110
Stock: In-stock

Carbocisteine Sulfoxide (Mixture of diastereomers)

CAS No.: 5439-87-2
Molecular Formula: C₅H₉NO₅S
Molecular Weight: 195.19
CAT No.: CS-T-10465
Stock: In-stock

Clonazepam Related Compound A

CAS No.: 55198-89-5
Molecular Formula: C₁₅H₁₀ClN₃O₃
Molecular Weight: 315.71
CAT No.: CS-T-93429
Stock: In-stock

Pomalidomide Impurity 9

CAS No.: 13726-85-7
Molecular Formula: C10H18N2O5
Molecular Weight: 246.26
CAT No.: CS-O-10889
Stock: In-stock

Pyrimethamine EP Impurity B

CAS No.: 3275-44-3
Molecular Formula: C11H11ClN4
Molecular Weight: 234.7
CAT No.: CS-EN-00033
Stock: In-stock

L-(+)-Lactic Acid-13C3 Sodium Salt (20% W/W in H2O)

CAS No.: 201595-71-3
Molecular Formula: ¹³C₃H₅NaO₃
Molecular Weight: 115.04
CAT No.: CS-T-96077
Stock: In-stock

N-Acetyl SLB-1

CAS No.: 28291-60-3
Molecular Formula: C16H15NO2
Molecular Weight: 253.3
CAT No.: CS-O-16683
Stock: In-stock

Valaciclovir EP Impurity F Tosylate

CAS No.: 86150-61-0
Molecular Formula: C₁₄H₂₃NO₆S
Molecular Weight: 333.40
CAT No.: CS-O-08370
Stock: In-stock

N-Nitroso Dabigatran Etexilate

CAS No.: 2892260-29-4
Molecular Formula: C₃₄H₄₀N₈O₆
Molecular Weight: 656.53
CAT No.: CS-O-38916
Stock: In-stock

Bepotastine Isopropyl ester

CAS No.: 1807607-93-7
Molecular Formula: C₂₄H₃₁ClN₂O₃
Molecular Weight: 430.97
CAT No.: CS-O-16620
Stock: In-stock

Nebevilol Benzylated impurity

CAS No.: 929706-85-4
Molecular Formula: C₂₉H₃₁F₂NO₄
Molecular Weight: 495.56
CAT No.: CS-T-48935
Stock: In-stock

Propafenone EP Impurity F

CAS No.: 1329643-40-4
Molecular Formula: C₃₃H₃₂O₅
Molecular Weight: 508.60
CAT No.: CS-O-13597
Stock: In-stock

Sertraline Dimethyl Impurity HCl

CAS No.: 122873-20-5 (free base)
Molecular Formula: C18H20Cl3N
Molecular Weight: 356.72
CAT No.: CS-P-08882
Stock: In-stock

Carglumic Acid Impurity B

CAS No.: 5624-26-0
Molecular Formula: C₆H₈N₂O₄
Molecular Weight: 172.14
CAT No.: CS-O-12032
Stock: In-stock

Valsartan EP Impurity C

CAS No.: 952652-79-8
Molecular Formula: C₂₃H₂₇N₅O₃
Molecular Weight: 421.49
CAT No.: CS-O-08394
Stock: In-stock

Tacrolimus Impurity 2

CAS No.: 131944-48-4
Molecular Formula: C₄₄H₆₉NO₁₂
Molecular Weight: 804.02
CAT No.: CS-T-54717
Stock: In-stock

Ciclopirox Olamine EP Impurity B

CAS No.: 14818-35-0
Molecular Formula: C₁₂H₁₆O₂
Molecular Weight: 192.25
CAT No.: CS-T-51441
Stock: In-stock

Brexpiprazole Impurity 15

CAS No.: 913612-07-4
Molecular Formula: C25H29N3O2S
Molecular Weight: 435.60
CAT No.: CS-P-03468
Stock: In-stock

Picroside I

CAS No.: 27409-30-9
Molecular Formula: C₂₄H₂₈O₁₁
Molecular Weight: 492.47
CAT No.: CS-E-00936
Stock: In-stock

Glibenclamide EP Impurity A

CAS No.: 16673-34-0
Molecular Formula: C₁₆H₁₇ClN₂O₄S
Molecular Weight: 368.84
CAT No.: CS-T-11856
Stock: In-stock

Tenofovir alafenamide Impurity 1

CAS No.: 851456-00-3
Molecular Formula: --
Molecular Weight: --
CAT No.: CS-O-15852
Stock: In-stock

Canagliflozin impurity F

CAS No.: 1071929-08-2
Molecular Formula: C₁₈H₁₂FIOS
Molecular Weight: 422.26
CAT No.: CS-AQ-00195
Stock: In-stock

Regorafenib PmA Ethyl Carbamate Impurity

CAS No.: 2514957-39-0
Molecular Formula: C₁₆H₁₆FN₃O₄
Molecular Weight: 333.31
CAT No.: CS-O-14435
Stock: In-stock

Cetirizine EP impurity A

CAS No.: 303-26-4
Molecular Formula: C₁₇H₁₉ClN₂
Molecular Weight: 286.80
CAT No.: CS-O-31588
Stock: In-stock

Brimonidine EP Imprurity F

CAS No.: 151110-15-5
Molecular Formula: C₁₁H₈BrN₅
Molecular Weight: 290.12
CAT No.: CS-T-49908
Stock: In-stock

Dexamethasone Sodium phosphate EP Impurity B Disodium Salt

CAS No.: 151-73-5
Molecular Formula: C₂₂H₂₈FNa₂O₈P
Molecular Weight: 516.40
CAT No.: CS-O-30707
Stock: In-stock

Carvedilol EP Impurity B

CAS No.: 918903-20-5
Molecular Formula: C₃₉H₃₉N₃O₆
Molecular Weight: 645.74
CAT No.: CS-O-07545
Stock: In-stock

Diphenhydramine Impurity A

CAS No.: 53499-40-4
Molecular Formula: C₁₆H₂₀ClNO
Molecular Weight: 277.79
CAT No.: CS-M-53270
Stock: In-stock

Lansoprazole Thioxo Impurity

CAS No.: 1246819-06-6
Molecular Formula: C₁₄H₉N₃OS
Molecular Weight: 267.31
CAT No.: CS-O-10003
Stock: In-stock

Darunavir N-methyl urea impurity

CAS No.: 1451010-37-9
Molecular Formula: C₂₉H₄₀N₄O₈S
Molecular Weight: 604.71
CAT No.: CS-O-34249
Stock: In-stock