Diazepam and nordiazepam in plasma: Liquid-liquid and solid phase extraction in sample pretreatment for high performance liquid chromatography analysis.

Analysis of diazepam (DZP) and its active metabolite nordiazepam (NDZP) in plasma is commonly performed in clinical medicine to ensure proper therapeutic effects while minimizing the incidence of toxicity. This study aimed to optimize analytical parameters and compare two pre-treatment techniques, liquid-liquid (LLE) and solid phase extraction (SPE), as well as liquid chromatographic conditions to analyze simultaneously DZP and NDZP in plasma from 20 patients treated with a daily dose of 10 mg. Both techniques showed to be well in line with the international criteria for analytical validation, which permitted to quantify DZP (66.2 - 1148.6 ng mL(-1)) and NDZP (138.5 - 808.6 ng mL(-1)) in all samples. The correlation coefficients between SPE and LLE were respectively 0.9729 for DZP and 0.9643 for NDZP.