Stability of 3-chloromethcathinone and 4-chloromethcathinone during synthesis and storage.

Synthetic cathinones have been among the most commonly identified substances in forensic analyses for several years. The most frequently detected representatives of this group include 4-CMC and 3-CMC. These substances are synthesized in clandestine laboratories across Europe, mainly in Poland and the Netherlands. The study was inspired by real casework involving samples from clandestine laboratories, in which concentrations of cathinone derivatives decreased or these compounds became undetectable during storage. To support the interpretation of analytical results from such samples - particularly in cases involving delayed analysis, long-term storage of seized materials, or re-analysis of archived samples - the stability of 3-CMC and 4-CMC dissolved in reagents used at various steps of their illicit production was studied, including environments with different pH values. Different storage temperatures were tested, and the stability of these compounds in single- and biphasic liquid systems was evaluated. The obtained results demonstrated that both compounds exhibit high stability in acidic and neutral solutions, especially at low temperatures (4°C and -20°C), where no significant changes in concentration were observed even after one year of storage. At room temperature (25°C) in less acidic environments (pH 5), slow degradation was observed. In alkaline conditions, rapid decomposition of both substances was noted, depending on their initial concentration and storage temperature, with 3-CMC degrading faster than 4-CMC. Additionally, in biphasic liquid systems, contact between the organic phase containing the cathinone and an alkaline aqueous phase significantly increased degradation over time, with this effect being more pronounced for 3-CMC than for 4-CMC.