Stability tests of zopiclone in whole blood

Influence of pre-analytical conditions on the interpretation of zopiclone concentrations in whole blood

“…2). We also confirmed the results from our previous study that zopiclone was stable less than 1 month in authentic blood after storage at 5 8C [4], but by weekly testing the stability could be investigated in more detail and established to less than 2 weeks.…”

“…Summary of remaining content of zopiclone after short-and long-term storage in days (d) at 20 8C, concentration of zopiclone [4]. In this study, a significant degradation of zopiclone was seen already after 24 h in some subjects (Fig.…”

“…Zopiclone was quantified by gas chromatography with neutral extraction (pH 7.0) and with nitrogen phosphorus detection (GC-NPD) [4].…”

“…Reference standards and stock solutions were prepared in acetonitrile with certified zopiclone (Sigma-Aldrich, St. Louis, MI, USA) to concentrations of 100, 10, 1 and 0.1 mg/mL. The reference standards and stock solutions were stored at À20 8C with a tested stability of at least 12 months [4]. Prazepam (Sigma-Aldrich, St. Louis, MI, USA) was prepared in methanol and used as internal standard (IS) with a concentration of 10 mg/mL.…”

Prevalence of medicinal drugs in suspected impaired drivers and a comparison with the use in the general Dutch population

“…In the blood samples of suspected impaired drivers zolpidem was found more frequently than zopiclone, although there is an equal use of both z-drugs in the general population. Zopiclone in whole blood degradates depending on time and temperature of storage and preanalytical factors have great impact on the analytical results [51]. Due to this, zopiclone may not be detected after use/exposure.…”