Acid-base reaction-based dispersive solid phase extraction of favipiravir using biotin from biological samples prior to capillary electrophoresis analysis

Abstract

In this study, an acid-base reaction-based dispersive solid-phase extraction method was developed for the extraction of favipiravir from deionized water, plasma and urine samples prior to its determination using a capillary electrophoresis-diode array detector. The target analyte was extracted from the samples using biotin as a green adsorbent. To reach this goal, the pH of the solution was first adjusted to 9.0 (using borate buffer), and the ionic strength of the solution was enhanced by adding sodium chloride (2.5%, w/v). Thereafter, an appropriate amount of biotin was dissolved in the solution and a homogenous phase was obtained. By adding hydrochloric acid to the solution, an acid-base reaction occurs via protonation of biotin, which decreases its solubility. During this procedure, the analyte was adsorbed onto the tiny particles of the produced adsorbent dispersed into the solution. The resulting mixture was sonicated to facilitate the adsorption of the analyte onto the adsorbent surface. After the collection of biotin particles through centrifugation, the analyte was eluted using acetonitrile and then used in the determination stage. Under the optimal extraction conditions, the calibration curve was linear from 250 to 3000 ng mL^-1 with a coefficient of determination of 0.9968. Low limit of detection, and quantification, good repeatability on the same day and different days (relative standard deviation ≤ 8.2%), and acceptable extraction recovery were accessed. The applicability of the method was examined by performing it on spiked plasma and urine samples, and its performance was verified.

Fig. 1. Extraction procedure steps.

Fig. 2. The effect of adsorbent type (a) and amount (b) on extraction efficiency. (a) Extraction conditions: sample, 5 mL deionized water spiked with favipiravir at 250 ng mL⁻¹; adsorbent amount, 30 mg; agitation type (time), vortex (1 min); acid solution concentration (volume), 0.5 mol L⁻¹ (300 μL); elution solvent (volume), ACN (200 μL); desorption time, 2 min; and centrifugation rate (time), 4000 rpm, 5 min. The error bars indicate the standard deviations of three repeated analyses. (b) Extraction conditions are the same as those discussed in the caption to Fig. 2a, except biotin was selected as the adsorbent.

Fig. 3. The effect of elution solvent type and volume on extraction efficiency. (a) Extraction conditions are the same as those discussed in the caption to Fig. 2b, except 1.0 min was selected as the optimum time of agitation. (b) Extraction conditions are the same as those discussed in the caption to Fig. 3a, except ACN was chosen as the eluent.