cis & trans isomers in crotamiton This blog post discusses a more efficient quality control (QC) method for the determination of the cis and trans isomers that comprise crotamiton used in the treatment of scabies and skin pruritus than the official protocols of the British Pharmacopoeia (BP) and Pharmacopeia of the People’s Republic of China (PPRC).

Both the Pharmacopoeia specify that the maximum percentage of cis isomer should be 15% of the sum of cis and trans isomers, and have published normal-phase liquid chromatography methods for isomer analysis.

Application Brief 138,Separation of Cis and Trans Isomers of Crotamiton Using an Acclaim C30 Column, (downloadable PDF) describes a convenient reversed-phase high-performance liquid chromatography (RP-HPLC) method using a reversed-phase column (Thermo Scientific Acclaim C30 column) with a simple acetonitrile/water mobile phase. The column is designed to provide high shape selectivity for separation of hydrophobic, structurally related isomers and unique selectivity complementary to other RP columns (e.g., C18). Although another method for analysis of cis and trans isomers of crotamiton by RP-HPLC has been reported, it requires a three-component mobile phase (acetonitrile/phosphate buffer containing 1% triethylamine) to achieve satisfactory results.

The method was developed on our rapid-separation liquid chromatography (RSLC) system (Thermo Scientific Dionex UltiMate 3000 RSLC system).

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