Applying cloud point extraction technique for the extraction of oxazepam from human urine as a colour or fluorescent derivative prior to spectroscopic analysis methods

Abstract

Two new methods based on cloud point extraction (CPE) technique were developed and optimized for the extraction and preconcentration of oxazepam from human urine, as an azo or fluorescent derivative. The first method is a spectrophotometric one, which is based on the acid hydrolysis of the oxazepam to a benzophenone, diazotization of the benzophenone, and then the coupling with oxine to form an azo dye. The second method is a spectrofluorimetric one, which involves reduction of the target compound using Zn°/HCl at room temperature with the formation of a highly fluorescent derivative. The main factors affecting the chemical reactions and CPE were investigated and optimized systematically. Under optimum experimental conditions, the calibration graphs were linear in the range of 0.1 to 1.5 (0.05 to 2.0) µg/ml with correlation coefficients of 0.9989 (0.9985), for the CPE-spectrophotometric (CPE-spectrofluorimetric) method. The limit of detection was found to be 0.034 (0.018) µg/ml and the relative standard deviation was calculated to be 1.35 (2.52)%. Recoveries in the spiked samples ranged from 87 to 94%. Finally, the proposed methods were applied to the determination of oxazepam in human urine.

Benzodiazepines in complex biological matrices: Recent updates on pretreatment and detection methods

“…Tabrizi et al. [ 54 ] used 1.5 mL of non-ionic surfactant having properties of non-flammability and non-volatility in the CPE process to extract oxazepam from human urine. Recoveries of 87%–94% were obtained under optimized parameters affecting extraction efficiency, such as an equilibrium temperature of 40–45 °C.…”

An Overview on Total Analytical Methods for the Detection of 1,4-Benzodiazepines

“…The automated sample preparation setup also minimized human exposure to hazardous materials, provided highly improved ergonomics, and eliminated manual pipetting. Cloud point extraction (CPE) technique were developed and optimized for the extraction and preconcentration of oxazepam from human urine [45].…”

“…Spectrophotometric and chemometric studies on the simultaneous determination of two benzodiazepines in human plasma have been proposed that requires no preliminary separation steps [128]. A spectrophotometric method based on the acid hydrolysis of the oxazepam to a benzophenone was developed [45]. Three multivariate modelling approaches including partial least squares regression (PLS), genetic algorithm-partial least squares regression (GA-PLS), and principal components-artificial neural network (PC-ANN) analysis were investigated for the spectrophotometric determination of chlordiazepoxide in pharmaceuticals [129].…”

“…The developed spectrofluorimetric assay allowed determination of the photodegradation products at very low concentrations (≥10 −5 M) and it was successfully applied to the commercial tablets [132]. Another spectrofluorimetric method, which involves reduction of the target compound using Zn°/HCl at room temperature with the formation of a highly fluorescent derivative, was developed [45]. Fluorimetric methods have proved selective with low detection limits, whereas photometric methods showed relatively high detection limits.…”