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Impurities

SynThink is a trusted producer and supplier of Pharmaceutical Reference Standards, including Impurity Standards. These materials are essential for pharmaceutical companies conducting research into the quality, stability, and biological safety of drug products. We maintain a robust inventory of API impurities, ready to support your development and regulatory needs.

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Impurities, Methylprednisolone Acetate

11β,17α-Dihydroxy-17β-formyl-6α-methylandrosta-1,4-diene-3-one

$395.00 25 mg

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CAS No.

Mol F.

: C21H28O4

Mol W.

: 344.44

Cat No.

: SA25008

Impurities, Progesterone

15β-Hydroxy Progesterone

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CAS No.

: 600-72-6

Mol F.

: C21H30O3

Mol W.

: 330.46

Cat No.

: SA18018

Betamethasone Valerate

16-beta-Methyl Epoxide 17-Valerate

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CAS No.

: 52619-21-3

Mol F.

: C27H36O6

Mol W.

: 456.57

Cat No.

: SA18511

Impurities, Prednisone

16-Dehydro 17-Dehydroxy Prednisone

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CAS No.

: 102447-86-9

Mol F.

: C21H24O4

Mol W.

: 340.41

Cat No.

: SA26216

Exemestane, Impurities

16-Methylene 1,2-Dihydro Exemestane

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CAS No.

: NA

Mol F.

: C21H26O2

Mol W.

: 310.44

Cat No.

: SA19119

Desoximetasone, Impurities

16,17-Didehydro 16-Demethyl Desoximetasone

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CAS No.

: 1234572-33-8

Mol F.

: C21H25FO4

Mol W.

: 360.42

Cat No.

: SA19205

Impurities, Prednisone

16,21-Didehydro 17-Dehydroxy Prednisone

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CAS No.

: NA

Mol F.

: C21H22O4

Mol W.

: 338.4

Cat No.

: SA26209

Impurities, Progesterone

16α-Hydroxy Progesterone

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CAS No.

: 438-07-3

Mol F.

: C21H30O3

Mol W.

: 330.46

Cat No.

: SA18019

Flunisolide, Impurities

16α-Hydroxy-6α-fluoroprednisolone

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CAS No.

: 3915-36-4

Mol F.

: C21H27FO6

Mol W.

: 394.43

Cat No.

: SA47507

Impurities, Methylprednisolone

16α-MethylPrednisolone

$155.00 25 mg

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CAS No.

: 10417-63-7

Mol F.

: C22H30O5

Mol W.

: 374.47

Cat No.

: SA14420

Impurities, Methylprednisolone

16α-Methylprednisolone 21-Acetate

$555.00 25 mg

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CAS No.

: 13209-52-4

Mol F.

: C24H32O6

Mol W.

: 416.51

Cat No.

: SA14419

Exemestane, Impurities

16α, 17α-Epoxy Exemestane Impurity

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CAS No.

: NA

Mol F.

: C20H24O2

Mol W.

: 296.39999999999998

Cat No.

: SA19114

Halcinonide, Impurities

16α,17α-Dihydroxy Halcinonide

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CAS No.

: 982-91-2

Mol F.

: C21H28ClFO5

Mol W.

: 414.89

Cat No.

: SA30401

Ethinylestradiol, Impurities

16α,17α-Epoxy-19-norpregna-1,3,5(10)-trien-20-yn-3-ol Acetate

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CAS No.

: 55812-84-5

Mol F.

: C22H24O3

Mol W.

: 336.42

Cat No.

: SA13134

Ethisterone, Impurities

16β-Hydroxy-17-epi-norethisterone

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CAS No.

Mol F.

: C₂₀H₂₆O₃

Mol W.

: 314.42

Cat No.

: SA12902

Ethinylestradiol, Impurities

16β-Hydroxy-17α-Ethinylestradiol

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CAS No.

: 10084-25-0

Mol F.

: C20H24O3

Mol W.

: 312.41

Cat No.

: SA13116

Dutasteride, Impurities

17-carboxamide Dutasteride

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CAS No.

: 104214-61-1

Mol F.

: C19H28N2O2

Mol W.

: 316.44

Cat No.

: SA35213

Difluoroprednisolone, Impurities

17-Dehydroxy-17-des(hydroxyacetyl)-17β-methyl-6α,9α-Difluoroprednisolone

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CAS No.

Mol F.

: C20H26F2O2

Mol W.

: 336.42

Cat No.

: SA14209

Ethinylestradiol, Impurities

17-Dehydroxy-dehydro 17-epi-Ethinylestradiol

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CAS No.

: 71716-18-2

Mol F.

: C20H22O

Mol W.

: 278.39

Cat No.

: SA13125

Impurities, Norethindrone

17-Desethynyl 17-Dibromomethylaceto-norethindrone Acetate

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CAS No.

: 40228-41-9

Mol F.

: C22H28Br2O4

Mol W.

: 516.26

Cat No.

: SA13430

Impurities, Loteprednol

17-Methoxycarbonyl Loteprednol

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CAS No.

: 265651-89-6

Mol F.

: C23H29ClO7

Mol W.

: 452.92

Cat No.

: SA27608

Impurities, Methylprednisolone

17-O-Acetyl-6-methylprednisolone

$295.00 25 mg

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CAS No.

: 86401-94-7

Mol F.

: C24H32O6

Mol W.

: 416.51

Cat No.

: SA14416

Impurities, Norethindrone

17-O-Trimethylsilyl 6,7-Dehydro Norethindrone

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CAS No.

: 300542-58-9

Mol F.

: C23H32O2Si

Mol W.

: 368.58

Cat No.

: SA13432

Impurities, Norethindrone

17-O-Trimethylsilyl Norethindrone

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CAS No.

: 28426-43-9

Mol F.

: C23H34O2Si

Mol W.

: 370.6

Cat No.

: SA13433

Beclomethasone Dipropionate, Impurities

17,21-Dihydroxy-16β-methylpregna-1,4-diene-3,20-dione Dipropionate

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CAS No.

Mol F.

: C28H38O6

Mol W.

: 470.6

Cat No.

: SA15617

Equilin, Impurities

17α-Dihydro Equilin

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CAS No.

: 651-55-8

Mol F.

: C18H22O2

Mol W.

: 270.37

Cat No.

: SA16402

Ethinylestradiol, Impurities

17α-Dihydro-17β-ethinyl-equillenin

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CAS No.

Mol F.

: C20H20O2

Mol W.

: 292.37

Cat No.

: SA13133

Impurities, Norethindrone

17α-Ethinyl-17β-acetoxy-3,5-estradiene

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CAS No.

: 64850-62-0

Mol F.

: C22H28O2

Mol W.

: 324.46

Cat No.

: SA13434

Ethinylestradiol, Impurities

17α-Ethinylestradiol

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CAS No.

: 57-63-6

Mol F.

: C20H24O2

Mol W.

: 296.41

Cat No.

: SA13117

Exemestane, Impurities

17α-hydroxy-17β-Acetyl Exemestane

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CAS No.

: 1160599-91-6

Mol F.

: C22H28O3

Mol W.

: 340.46

Cat No.

: SA19120

Halcinonide, Impurities

17β-carboxylic acid Halcinonide

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CAS No.

: NA

Mol F.

: C23H31FO6

Mol W.

: 422.49

Cat No.

: SA30415

Equilin, Impurities

17β-Dihydro Equilin

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CAS No.

: 3563-27-7

Mol F.

: C18H22O2

Mol W.

: 270.37

Cat No.

: SA16403

Ethinylestradiol, Impurities

17β-Dihydro-17α-ethinyl-14β-equillenin

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CAS No.

Mol F.

: C20H20O2

Mol W.

: 292.37

Cat No.

: SA13132

Estradiol, Impurities

17β-Estradiol 3-O-Sulfate Sodium Salt

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CAS No.

: 4999-79-5

Mol F.

: C₁₈H₂₃NaO₅S

Mol W.

: 374.43

Cat No.

: SA13215

Estradiol, Impurities

17β-Estradiol Diacetate

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CAS No.

: 3434-88-6

Mol F.

: C₂₂H₂₈O₄

Mol W.

: 356.46

Cat No.

: SA13213

Estradiol, Impurities

17β-Estradiol Dimethyl Ether

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CAS No.

: 4954-14-7

Mol F.

: C₂₀H₂₈O₂

Mol W.

: 300.44

Cat No.

: SA13212

Estradiol, Impurities

17β-Estradiol; Estradiol Valerate Impurity A

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CAS No.

: 50-28-2 (anhydrous); 35380-71-3 (hemihydrate)

Mol F.

: C18H24O2 (anhydrous); C18H24O2 . 1/2 H2O (hemihydrate)

Mol W.

: 272.38 (anhydrous); 281.40(hemihydrate)

Cat No.

: SA13211

Exemestane, Impurities

17β-Hydroxy Exemestane

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CAS No.

: 122370-91-6

Mol F.

: C₂₀H₂₆O₂

Mol W.

: 298.42

Cat No.

: SA19116

Exemestane, Impurities

17β-Hydroxy Exemestane Sulfamate

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CAS No.

: NA

Mol F.

: C20H27NO4S

Mol W.

: 377.5

Cat No.

: SA19115

Ethinylestradiol, Impurities

18-Methyl Ethinylestradiol

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CAS No.

: 14012-72-7

Mol F.

: C21H26O2

Mol W.

: 310.43

Cat No.

: SA13129

Aprepitant, Impurities

1R, 2S, 3S-CAH impurity

$550.00 25 mg

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CAS No.

: 1333998-27-8 (HCl); 170902-80-4 (Base)

Mol F.

: C20H19ClF7NO2

Mol W.

: 473.81

Cat No.

: SA43702

Aprepitant, Impurities

1S, 2R, 3R-CAH impurity

$550.00 25 mg

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CAS No.

: 1333998-21-2 (HCl salt); 1242175-36-5

Mol F.

: C20H19ClF7NO2

Mol W.

: 473.81

Cat No.

: SA43705

Aprepitant, Impurities

1S, 2S, 3S-CAH impurity

$550.00 25 mg

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CAS No.

: 1242175-38-7 (Base); 1333995-14-4 (HCl salt)

Mol F.

: C20H19ClF7NO2

Mol W.

: 473.81

Cat No.

: SA43706

Eplerenone, Impurities

1α-Hydroxy Mexrenone

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CAS No.

: 192704-56-6

Mol F.

: C24H32O6

Mol W.

: 416.51

Cat No.

: SA41809

Cariprazine, Impurities

2-((1r,4r)-4-(3,3-Dimethylureido)cyclohexyl)acetic acid

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CAS No.

: 1957145-59-3

Mol F.

: C11H20N2O3

Mol W.

: 228.3

Cat No.

: SA39717

Impurities, Ribociclib

2-((2-Chloro-7-cyclopentyl-7H-pyrrolo[2,3-d]pyrimidin-6-yl)methoxy)-7-cyclopentyl-N,N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide

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CAS No.

: NA

Mol F.

: C26H30ClN7O2

Mol W.

: 508

Cat No.

: SA47113

Impurities, Tofacitinib

2-((3R,4R)-4-Methyl-3-(methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino)piperidin-1-yl)-2-oxoacetic acid

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CAS No.

: 2328165-36-0

Mol F.

: C15H19N5O3

Mol W.

: 317.34

Cat No.

: SA43311

Impurities, Ribociclib

2-((5-((2-Aminoethyl)amino)pyridin-2-yl)amino)-7-cyclopentyl-N,N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide

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CAS No.

: 2460738-27-4

Mol F.

: C21H28N8O

Mol W.

: 408.5

Cat No.

: SA47101

Carbamazepine, Impurities

2-((Triisopropylsilyl)oxy)-5H-dibenzo[b,f]azepine

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CAS No.

: NA

Mol F.

: C23H31NOSi

Mol W.

: 365.58

Cat No.

: SA20342

Carbamazepine, Impurities

2-((Triisopropylsilyl)oxy)-5H-dibenzo[b,f]azepine-5-carboxamide

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CAS No.

: NA

Mol F.

: C24H32N2O2Si

Mol W.

: 408.61

Cat No.

: SA20322