Stability of synthetic cathinones in clinical and forensic toxicological analysis—Where are we now?

Abstract

Understanding the stability of analyzed drugs in biological samples is a crucial part for an appropriate interpretation of the analytical findings. Synthetic cathinones, as psychoactive stimulants, belong to a major class of new psychoactive substances. As they are subject to several degradation pathways, they are known to clinical and forensic toxicologists as unstable analytes in biological samples. When interpreting analytical data of synthetic cathinones in biological samples, analysts must be aware that the concentration of analytes may not accurately reflect the levels at the time they were acquired owing to many factors. This review provides (i) an overview of the current scientific knowledge on the stability of synthetic cathinones and/or metabolites in various human biological samples with a focus on factors that may deteriorate their stability-such as storage temperature, length of storage, matrix, pH, type of preservatives, concentration of analytes, and the chemistry of the analytesand (ii) possible solutions on how to avoid such degradation. The PubMed database as well as Google Scholar was thoroughly searched to find published studies on the stability of synthetic cathinones since 2007 by searching specific keywords. A total of 23 articles met the inclusion criteria and were included in this review. Synthetic cathinones that carry methylenedioxy or N-pyrrolidine ring showed higher degradation resistance over other substituted groups. Acidification of samples pH plays a crucial role at increasing the stability of cathinones even with analytes that were frequently considered as poorly stable. This review also provides several recommendations for best practice in planning the experimental design, preservation, and storage conditions in order to minimize synthetic cathinones' degradation in human biological samples.

A Quantitative LC–MS/MS Method for the Detection of 16 Synthetic Cathinones and 10 Metabolites and Its Application to Suspicious Clinical and Forensic Urine Samples

“…It is also likely that target analytes were present in the samples at very low levels (<LOD) owing, for instance, to their degradation in the matrix. Indeed, samples were stored from one to six months, and there is evidence strongly suggesting the tendency of this class to degrade over time, even when stored at low temperatures [ 38 ].…”

Frequency of new psychoactive substances in hair and urine samples of individuals subject to drug testing in driving license regranting—A toxicological perspective

“…This may especially be the case for the detection rate of designer drugs including synthetic cathinones which are known to be unstable in biological samples. 16 The instability of many of these substances may have contributed to the very low detection frequencies of designer drugs.…”

Enhanced electrochemical detection of illicit drugs in oral fluid by the use of surfactant-mediated solution

“…During these tests, Cl-PVP was excluded as the oxidation potentials of this drug fall in the potential window of an oral fluid interferent (between 0.5 -0.7 V). Besides, a lack of stability of synthetic cathinones might be expected in oral fluid, making it difficult for its quantification [54]. Importantly, a slight peak potential shift is observed when dealing with oral fluid samples instead of buffer, highlighting the importance of the analysis of complex matrices when dealing with the development of analytical devices.…”