Stability of diazepam's phase II metabolites in dried blood spots on filter paper.

Phase II metabolites play an important role in diazepam-related cases. The study aimed to assess the stability of diazepam's phase II metabolites in dried blood spots on filter paper. A piece of filter paper was spotted with 100 µL of whole blood (added 1% sodium fluoride as needed) obtained from participant who received 5 mg diazepam orally, air dried for 2 h at room temperature, and then stored at different conditions. Whole spots were cut at 0.1 cm from the outer edge of blood spots at post-consumption time-points of prior (zero), 5, 16, 35, 61, 120 days and 1, 1.5 years. Analytes were extracted with methanol/water mixture (8:2, v/v) and determined using HPLC-MS/MS. Decomposition rules were analyzed by a statistical software "SPSS". Temazepam glucuronide remained stable (0.5–18.6% loss) at 20 ℃ and at 20 ℃ with 1% sodium fluoride for 16 days, while it was unstable after 5 days at 4 ℃ (21.1–26.2% loss) and − 20 ℃ (28.9 - 34.4% loss). After 35 days, temazepam glucuronide concentrations began to fluctuate significantly under all conditions, and an obvious increase (290.4–355.1%) was observed in 1.5 years. Oxazepam glucuronide was always unstable after 5 days, the percentage loss was even 100% when it was stored for 61 days and 1.5 years. Dried blood spots on ordinary filter paper are recommended to be stored at 20 ℃ or 20 ℃ with 1% sodium fluoride within 16 days. Samples should be analyzed immediately or stored in sterile and dry media. • TG was stable on filter paper at 20 ℃ with or without 1 % NaF within 16 days, and it is a more reliable marker in real cases. • OG was always unstable after 5 days, the percentage loss was even 100% when it was stored for 61 days and 1.5 years. • DBS on filter paper in diazepam-related cases are recommended to be stored at 20 ℃ with or without 1 % NaF within 16 days. [ABSTRACT FROM AUTHOR]