[Solvent with switchable hydrophilicity used in liquid-liquid microextraction combined with gas chromatography-mass spectrometry for the determination of diclazepam in urine].

A simple, fast, and sensitive method was developed for the determination of diclazepam in urine using a solvent with switchable hydrophilicity in liquid-liquid microextraction followed by gas chromatography-mass spectrometry. N,N-Dimethylcyclohexylamine was used as the extraction solvent with switchable hydrophilicity, because it can be made miscible or immiscible with aqueous phase by adding hydrochloric acid and sodium hydroxide. Experimental parameters affecting the extraction efficiency, such as the volume of hydrochloric acid, the type and volume of the solvent with switchable hydrophilicity, the volume of sodium hydroxide, and the extraction time, were investigated. Under the optimal conditions, the intraday and interday recoveries ranged from 76.5% to 90.3% with relative standard deviations between 3.3% and 6.5% (n=6). The linear range was found to be 0.025-2.5 mg/L, with r2 greater than 0.99 and limit of detection of 0.007 mg/L. This method provided excellent linearity, precision, and recovery, and thus, can be applied to the analysis of diclazepam in urine due to its simplicity, accuracy, and practicality.