title: Experimental design for optimization of microwave-assisted extraction of benzodiazepines in human plasma.
abstract: A simple and fast microwave-assisted-extraction (MAE) method has been evaluated as an alternative to solid-phase extraction (SPE) for the determination of six benzodiazepines widely prescribed in European countries (alprazolam, bromazepam, diazepam, lorazepam, lormetazepam and tetrazepam) in human plasma. For MAE optimization a Doehlert experimental design was used with extraction time, temperature and solvent volume as influential parameters. A desirability function was employed in addition to the simultaneous optimization of the MAE conditions. The analysis of variance showed that the solvent volume had a positive influence on the extraction of all the analytes tested, achieving a statistically significant effect. Also, the extraction time had a statistically significant effect on the extraction of four benzodiazepines. The selected MAE conditions-89 degrees C, 13 min and 8 mL of chloroform/2-propanol (4:1, v/v)-led to recoveries between 89.8 +/- 0.3 and 102.1 +/- 5.2% for benzodiazepines using a high performance liquid chromatography method coupled with diode-array detection. The comparison of MAE and SPE shows better results for MAE, with a lower number of steps in handling the sample and greater efficiency. The applicability of MAE was successfully tested in 27 plasma samples from benzodiazepine users.
authors.affiliation: Institute of Legal Medicine, Forensic Toxicology Service, Faculty of Medicine, 15782, Santiago de Compostela, Spain. puri.fernandez@usc.es
authors.forename: P
authors.initials: P
authors.lastname: Fernández
authors.forename: C
authors.initials: C
authors.lastname: Vázquez
authors.forename: R A
authors.initials: RA
authors.lastname: Lorenzo
authors.forename: A M
authors.initials: AM
authors.lastname: Carro
authors.forename: I
authors.initials: I
authors.lastname: Alvarez
authors.forename: P
authors.initials: P
authors.lastname: Cabarcos
mesh_terms: D001569:Benzodiazepines / Q000097:blood* / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D008872:Microwaves
chemical_list: D001569:Benzodiazepines