A comparative study of primary secondary amino (PSA) and multi‐walled carbon nanotubes (MWCNTs) as QuEChERS absorbents for the rapid determination of diazepam and its major metabolites in fish samples by high‐performance liquid chromatography–electrospray ionisation–tandem mass spectrometry

BACKGROUND A simple and fast modified quick, easy, cheap, effective, rugged, and safe ( QuEChERS ) method is presented for the determination of diazepam and its three major metabolites, nordiazepam, temazepam and oxazepam (benzodiazepines) in fish samples by liquid chromatography–electrospray ionisation–tandem mass spectrometry. RESULTS Muscle tissues were extracted with acetonitrile, and then cleaned with primary secondary amino ( PSA ) adsorbents. The cleanup effect of PSA was compared with that of multi‐walled carbon nanotubes (MWCNTs) in term of extraction efficiency. The better results were obtained when PSA was used. The chromatography separation was achieved within 5.0 min on a C 18 column. The limit of detection was 0.5 µg kg −1 and the limit of quantification was 2.5 µg kg −1 . Average recoveries of diazepam and its main metabolites were in the range of 88.5–110.1%, with a relative standard deviation lower than 10.0%. CONCLUSION The proposed method for fish samples gives good recoveries, linearity, precision and accuracy.