Sensitive determination of psychotropic drugs in urine samples using continuous liquid-phase microextraction with an extraction solvent lighter than water

Abstract

A novel extraction vessel was employed, for the first time, in continuous liquid-phase microextraction (CLPME) with an extraction solvent lighter than water for the extraction of psychotropic drugs from urine samples. In this method, firstly, 4.7 mL of ultra-pure water was poured into the extraction vessel. Then 30.0 μL of the extraction solvent was added to it in order for the extraction solvent to be placed in the narrow-necked vessel. A standard solution or a real sample (10 mL) was then added to the sample container and connected to the extraction vessel via a connector. Upon opening the embedded valve in the bottom of the sample container and the one in the extraction vessel, the sample solution can easily flow into the extraction solvent with the same flow rate, leading to the successful extraction of analytes into the extracting organic solvent. From the calibration curves, the linear dynamic range was observed to be 1–800 μg L⁻¹ and the limits of detection (LODs) were found to range from 0.35 μg L⁻¹ to 0.7 μg L⁻¹. The extraction recoveries were calculated to be in the range of 56.2 to 69.5%, and enrichment factors were obtained to range from 224.8 to 278 for amitriptyline and clomipramine, respectively. Repeatability and reproducibility of the method were measured for 50.0 μg L⁻¹ of amitriptyline and clomipramine, which were in the range of 4.6–5.3% and 5.8–6.5%, respectively. The applicability of the proposed method, CLPME coupled with HPLC-UV, was demonstrated by analyzing the spiked drugs in urine samples. The obtained recoveries of the drugs were in the range of 94.2–105.6%, indicating the excellent capability of the developed method for extraction of psychotropic drugs from urine samples.