Determination of Victoria blue in water samples using ultrasound-assisted liquid-phase microextraction based on deep eutectic solvents: A comparative study of spectrophotometric and smartphone imaging techniques

Abstract

In this research, the ultrasound-assisted liquid-phase microextraction (US-LPME) method based on the deep eutectic solvent (DES) was performed for preconcentration and extraction of Victoria Blue R (VBR) dye in water samples. In the US-LPME-DES method, a 1:1 ratio of choline chloride and oxalic acid (ChCl: OA) as the DES was optimized in the extraction process. The effect of analytical parameters on the extraction efficiency was studied and optimized using a response surface methodology based on experimental design. A central composite design (CCD) was employed to optimize the main parameters, including the initial pH of the aqueous dye solution, and the volume of DES and diluent. The quantitative determination of the extracted VBR was performed using both spectrophotometry and smartphone imaging (SPI) techniques. The method demonstrates excellent linearity (0.010–3.0 and 0.01–4.0 mg/L), high coefficient determination (R² = 0.9996 and 0.9985), and low detection limits (3.0 and 4.2 µg/L) using both spectrophotometry and SPI. In the selectivity tests of the method, the presence of various ions and dyes doesn’t show significant interference in the selective determination of VBR. The US-LPME-DES method was successfully applied to recover VBR from various water samples, too. The acceptable precision, accuracy, and efficiency confirmed the applicability of the present method for real sample analysis.