Screen-printed anion-exchange solid-phase extraction: A new strategy for point-of-care determination of angiotensin receptor blockers.

A miniaturized system of anion exchange solid phase extraction (SPE) based on a screen-printed electrode was developed as a point of care (POC) device for extraction and quantitative determination of anionic analytes. Nylon 6/polyaniline nanofibers were fabricated by electrospinning and in-situ oxidative polymerization techniques coated on a screen-printed working electrode and characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. The effects of essential parameters such as desorption conditions, pH of the sample solution, adsorption voltage, adsorption time, and salt concentration on the performance of the method were investigated. To evaluate the performance of the system, angiotensin ΙΙ receptor antagonists, including valsartan, losartan, and irbesartan, were selected as model compounds and analyzed by HPLC/UV after extraction. The limits of detection and quantification were ranging between 0.4 and 0.9 µg L-1 and 1.3-3.0 µg L-1, respectively. The linear dynamic range for Losartan, Irbesartan, and Valsartan was 2-400, 4-1000, and 2-400 µg L-1, respectively, with R2 > 0.991. Finally, the method was applied for the determination of ARA-IIs in human blood plasma samples, and relative recoveries in the range of 89.0-107.8% with relative standard deviation (RSDs (≤8.9% were obtained.

Developing a miniaturized setup for in-tube simultaneous determination of three alkaloids using electromembrane extraction in combination with ultraviolet spectrophotometry.

Herein, electromembrane extraction was combined with ultraviolet spectrophotometry using a customized manifold for preconcentration and simultaneous determination of morphine, codeine, and papaverine in water and human urine samples. Absorption spectra of the extracts were recorded inside the lumen of the hollow fiber using two fiber optics connected to a miniature spectrophotometer. Partial least squares regression was applied to resolve the overlapped spectra of the analytes. Performance of the model was validated by an independent test set. Central composite design was applied to optimize the extraction parameters. The optimized extraction conditions are as follows; supporting liquid membrane: 2-nitrophenyl octyl ether containing 15% v/v bis(2-ethylhexyl) phosphate, applied voltage: 80 V, donor pH: 3.0, acceptor pH: 1.0, extraction time: 20 min. Finally, the optimized extraction method was validated for determination of the mentioned alkaloids in human urine samples. The method showed good linearity (R2  > 0.995) for all of the mentioned alkaloids. The limits of detection for morphine, codeine, and papaverine in diluted human urine were found to be 0.6, 1.1, and 0.6 ng/mL, respectively with acceptable relative standard deviations. Enrichment factors of 104, 108, and 102 were achieved for morphine, codeine, and papaverine, respectively.