The synthetic cathinones are powerful psychostimulants that have been associated with impairment, intoxication and fatal overdose. Forensic laboratories must be able to identify these new drugs as part of antemortem and postmortem toxicology investigations. Preliminary reports have indicated that some of the synthetic cathinones are unstable in biological matrices. It is important to understand drug stability in biological evidence so that analytical findings can be interpreted appropriately. The objective of this study was to systematically evaluate the concentration, temperature and analyte-dependent stability of synthetic cathinones in preserved blood using liquid-chromatography/quadrupole-time of flight-mass spectrometry (LC/Q-TOF-MS). Cathinone stability was investigated at frozen, refrigerated, ambient and elevated temperature (-20°C, 4°C, 20°C and 32°C). Although no concentration dependent differences in stability were observed, cathinone stability was highly temperature and analyte-dependent. Substituents on the aromatic ring and nitrogen profoundly influenced stability. Tertiary amines (pyrrolidinyl analogs) were significantly more stable than their N-alkylated (secondary amine) counterparts. Furthermore, the methylenedioxy (MD) group also exerted a significant stabilizing effect, for both secondary and tertiary amines. The unsubstituted and ring-substituted secondary amines were the least stable, most notably 3-fluoromethcathinone (3-FMC). Under some conditions, significant losses were observed within hours of storage. Half-lives ranged from a little as 8 h (3-FMC) to 21 days (3,4-methylenedioxy-α-pyrrolidinobutiophenone, MDPBP) at elevated temperature (32°C). In contrast, half-lives ranged from 0.4 to >10 months when refrigerated and demonstrated even greater stability when frozen. Biological evidence may be subjected to a variety of environmental conditions prior to, and during transport to the laboratory. These findings highlight the need to consider the potential for both temperature and analyte-dependent differences. Due to the inherent instability of certain drugs within the class, quantitative drug findings in toxicological investigations must be interpreted with caution, and within the context of specimen storage and integrity.

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In this report, we evaluate the concentration, pH, temperature and analyte-dependent effects on cathinone stability in preserved human urine. A total of 22 synthetic cathinones were evaluated at 100 ng/mL and 1,000 ng/mL in pH 4 and pH 8 urine over 6 months. Specimens were stored at -20°C, 4°C, 20°C and 32°C. The stability of synthetic cathinones was highly dependent on urine pH and storage temperature. Cathinones were considerably more stable in acidic urine (pH 4) at low temperature. In alkaline urine (pH 8) at 32°C, significant losses (>20%) were observed within hours for the majority of drugs. In contrast, all drugs were stable in frozen and refrigerated urine at pH 4 for the duration of the study. These results highlight the importance of sample storage and the potential for pre-analytical changes in concentration during routine shipping and handling of specimens. Significant structural influence was also observed. Cathinones bearing a tertiary amine (pyrrolidine group) were significantly more stable than their secondary amine counterparts. The methylenedioxy group also exerted a significant stabilizing effect on both the tertiary and secondary amines. In the absence of the methylenedioxy group, no significant differences in stability were observed between the unsubstituted and ring substituted secondary amines. Half-lives at ambient temperature in pH 8 urine ranged from 9 h (3-fluoromethcathinone) to 4.3 months (methylenedioxypyrovalerone and 3,4-methylenedioxy-α-pyrrolidinobutiophenone), demonstrating the importance of analyte dependence, and the dual stabilizing effect of both the pyrollidine and methylenedioxy groups. Biological evidence may be subjected to a variety of environmental conditions prior to, and during transport to the forensic laboratory. These findings demonstrate the inherent instability of certain cathinone species in biological evidence under some conditions. Moreover, this study highlights the need for quantitative drug findings in toxicological investigations to be interpreted cautiously, and within the context of specimen storage and integrity.

The opioid epidemic resulted in an increase in identifications of fentanyl, fentanyl analogs, and heroin, among other opioids, in the toxicology and seized drug analysis fields over the past several years. The Dallas County Southwestern Institute of Forensic Sciences, comprised of the Toxicology Laboratory and Drug Analysis Laboratory, observed a rise in fentanyl-positive analyses in both laboratories. Fentanyl positivity increased from 1.1% to 3.4% in the Toxicology Laboratory over the five years of this study, whereas 6-monoacetylmorphine (6-MAM) positivity remained relatively stable at approximately 2%. Similarly, in the Drug Analysis Laboratory, the fentanyl positivity rate changed from 0.03% to 0.60%, whereas heroin identification remained stable at approximately 8-9%. Based on data obtained from toxicology submissions, a typical fentanyl or heroin user was a white male in their late 30s. The average concentration of fentanyl in postmortem cases, antemortem cases, and 6-MAM in postmortem specimens was 9.7 ng/ml, 5.5 ng/ml, and 68.4 ng/ml, respectively. Poly-drug use was evident, with benzodiazepines being the most commonly co-administered drug with fentanyl (49.4%). Multiple drugs were identified via analysis of clandestine tablets submitted to the Drug Analysis Laboratory, including fentanyl and/or heroin in combination with compounds such as cocaine, etizolam, and acetaminophen. The most frequently identified clandestine tablet was "M367," typically manufactured to contain acetaminophen and hydrocodone, but was found to contain fentanyl or heroin. The results from this study aid in the understanding of the current opioid trends in Dallas County and provides an opportunity for comparison to other populations and geographical regions.