Extraction and determination of three benzodiazepines in aqueous and biological samples by air-assisted liquid–liquid microextraction and high-performance liquid chromatography

Abstract

Air-assisted liquid–liquid microextraction (AALLME) as a simple and efficient method was used for extraction of three benzodiazepines (chlordiazepoxide, alprazolam, and lorazepam) in aqueous and biological samples. High-performance liquid chromatography with UV detector was applied for separation and determination of these drugs. To optimize the extraction recovery, effects of seven parameters such as type and volume of extraction solvent, pH and ionic strength of sample solutions, extraction time, centrifugation rate, and time were investigated. Under the optimum condition (chloroform volume as extraction solvent = 300 µL, pH of sample solutions = 7, with 10% w/v salt, number of extraction = 12 cycles, centrifugation rate, and time equal 4000 rpm and 9 min), linearity of the method was from 3 to 10 to 800–1100 µg L−1 for these compounds. Limit of detections was 0.7–2.9 µg L−1. Relative standard deviations for the extraction of 20 and 50 µg L−1 of these benzodiazepines (n = 3) were in the ranges of 1.6–3.1–0.9–2.1%, respectively. This method was successfully applied for extraction and determination of benzodiazepines in different samples such as tap water, tablets, fruit juice, plasma, and urine. Extraction recovery for chlordiazepoxide, alprazolam, and lorazepam was 81.2%, 92.1%, and 90.1%, respectively.