Identification of the impurities in o-chlorophenyl cyclopentyl ketone samples by high performance liquid chromatography-hybrid ion trap/time-of-flight mass spectrometry and preparation of o-chlorophenyl cyclopentyl ketone standard

Abstract

A method for the identification of relevant impurities in illegal o-chlorophenyl cyclopentyl ketone drug was developed. Identification of impurities could help regulation of this illegal drug and allow the sources of samples of the drug to be identified. An efficient and effective method for qualitatively analyzing samples using high performance liquid chromatography-hybrid ion trap/time-of-flight mass spectrometry (HPLC-IT/TOF MS) was developed. The o-chlorophenyl cyclopentyl ketone fragmentation pathway during HPLC-MSn was determined by analyzing a standard by HPLC-IT/TOF MS. The optimized HPLC-IT/TOF MS method allowed two impurities in o-chlorophenyl cyclopentyl ketone samples to be identified. According to the exact mass data of MSn and the element composition analysis, two impurities were identified as o-chlorobenzoic acid anhydride and 1,2-di-o-chlorobenzoylcyclopentene. The synthetic route of the o-chlorophenyl cyclopentyl ketone samples was proposed by analysis of these impurities. The established method made it easy to identify impurities and find the source of this illegal drug. A method for the preparation an o-chlorophenyl cyclopentyl ketone reference standard from actual samples using preparative HPLC was also developed. The mobile phase was methanol-water (85:15, v/v) and flow rate was 8 mL/min. The purity of the obtained standards, determined by analytical HPLC, was 99.53%. This method is simple, efficient, and can be used for the preparation of other illegal drugs.