LAUSR

Determination of new psychoactive substances (NPS) and interpretation of the results of research on them is a challenge for both clinical and forensic toxicologists. Among others, scientists undertake to develop methods for rapid determination of NPS in biological material or examine their pharmacokinetic and pharmacodynamic properties. Adequately quick determination of substances in biological material may help in choosing the right treatment method and thus protect patients from serious health consequences or even death. On the other hand, post-mortem toxicological analysis may help to determine the cause of death and prevent similar cases in the future. The results of post-mortem examinations are influenced by thanatochemical processes. Post-mortem changes negatively affect the stability of the substances in biological material, especially when the body is in a state of progressive putrefaction. Researchers [1–5] undertook studies into the stability of NPS in various biological matrices, including synthetic cathinones such as 4-methylmethcathinone (4-MMC), 4-ethylmethcathinone (4-EMC), and 3,4-dimethylmethcathinone (3,4-DMMC). However, none of the abovementioned studies examined the stability of 4-chloromethcathinone (4-CMC) in biological material. The authors of this study noticed the need to carry out research in this area because 4-CMC is highly unstable at 4 °C. The significance of research into this substance is further reinforced by the European Drug Report 2018 [6], according to which in 2016 in Europe 4-CMC was the second most frequently confiscated cathinone and the one seized in the largest amount (890 kg). This letter presents a study of 4-CMC stability in a blood serum sample without any preservatives (obtained from a person taking 4-CMC), stored at 4 °C. The 4-CMC, (1-(4-chlorophenyl)-2-(methylamino)-1propanone), also known as clephedrone, was first introduced to online sales in 2014 [7]. Although this substance has been available on the black market for several years, the results of research on, among others, its pharmacokinetic properties, toxic doses, effects of use, or addictive potential remain insignificant. Information on patterns of use are usually passed between users via online forums [8]. Tomczak et al. [8] determined that the blood concentration of 4-CMC in non-fatal cases ranged from 1.3 to 75.3 ng/mL (n = 9) and in fatal cases from 56.2 to 1870 ng/mL (n = 5). The discussed case concerns a 27-year-old incarcerated man. The reason for ordering toxicological tests is unknown. There is also no information about the medical or drug history of the man. The material submitted for testing in the form of blood serum was screened for numerous drugs. The serum was extracted with ethyl acetate from alkaline medium (pH 9). The analysis was carried out using the technique of ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-QqQ-MS/MS). Calibration range 0.5–100 ng/mL; LOQ: 0.5 ng/mL. 4-MMC-d3 was used as an internal standard. Figure 1 shows the chromatogram obtained from first analysis with MRM transitions for 4-CMC and IS. Figure 2 shows mass spectra of 4-CMC. At the time of the first analysis (day 0), the 4-CMC concentration was 11.5 ng/mL. Subsequent analyses were conducted on the days 3, 8, 16, 27, 47, and 113. The sample was stored at 4 °C throughout the testing period. Table 1 shows 4-CMC concentrations on subsequent days. The tests demonstrated that 4-CMC was unstable in a blood serum sample stored at 4 °C. As early as 3 days after the first quantitative measurement, the analyte concentration dropped by 65% (11.5 ng/mL at day 0 vs. 4.0 ng/mL at day 3). The analyte was considered stable if the concentration differences were within ± 20% of the initial concentration. On day 47, the analyte concentration slightly exceeded LOQ * Karolina Nowak [email protected]