Influence of long-term storage temperatures and sodium fluoride preservation on the stability of synthetic cathinones and dihydro-metabolites in human whole blood

Abstract

Purpose Synthetic cathinones, one of the largest groups of new psychoactive substances, represent a large analytical and interpretative challenge in forensic laboratories. Of these is the synthetic cathinones’ instability in different biological samples, which may lead to drug concentration discrepancies when interpreting toxicological findings. In this study, the stability of a panel of synthetic cathinones and their dihydro-metabolites (n = 26) together with internal standard was monitored in human whole blood stored at various temperatures over 6 months. The influence of sodium fluoride as a preservative in blood collection tubes was also investigated. Methods Samples were extracted using a two-step liquid-liquid extraction technique, and analyzed using a validated liquid chromatography–tandem mass spectrometry method following recommendations of published guidelines. Results The influence of temperature over analytes’ stability was an important element in whole blood samples, with − 40 °C being the best storage temperature for all tested analytes. Sodium fluoride did not significantly affect the stability of cathinones except at room temperature. Dihydro-metabolites displayed better stability in whole blood samples and remained detectable for a longer period of time under all tested conditions. Conclusions The data suggest that samples containing synthetic cathinones should be analyzed immediately, if possible. Alternatively, whole blood samples should be stored frozen (at − 40 °C or lower); however, (quantitative) results should be interpreted with caution after long-term storage. The data also promote the use of dihydro-metabolites as biomarkers for synthetic cathinones intake, as these reduced metabolites may be detected for longer period of time when compared with parent drugs in whole blood samples.

Simultaneous Determination and Stability Analysis of Ten New Psychoactive Substances including Synthetic Cathinones, Phenethylamines, and Ketamine Substitutes in Urine Using Liquid Chromatography-Tandem Mass Spectrometry

“…Considering the polarity and solubility distribution of NPSs, we chose 50% methanol as one of the solvents for drug stability evaluation. Some previous studies that investigated the stability of synthetic cathinones used preservatives or buffers containing metal ions for different pH solutions [ 14 , 28 ]. However, metal ions may interfere with mass spectrometry or damage the instrument.…”

Naringenin as a Novel Stabilizer for Improving the Stability of 5-Methyltetrahydrofolate

“…34 Folate demonstrated poor stability data for the tested serum separator tubes, gel-free serum, and lithium heparin plasma. 7 In the preliminary study of measuring 5-MTHF, we observed the instability of 5-MTHF, which may affect the detection results and interfere with clinical diagnosis of disease, 8 including hyperhomocysteinaemia, 9 neural tube defects, 10 congenital malformations, 11 autoimmune disease, 3 and so on.…”