Dispersive Solid Phase Extraction Combined by Dispersive Liquid-Liquid Microextraction for Preconcentration of Brilliant Green from Fish and Seawater Samples and Its Determination by Spectrophotometry

A highly sensitive, simple, and speed technique was employed for the determination of brilliant green in fish (Sphyraena jello) and seawater samples by visible spectrophotometry after its extraction and enrichment with chitosan- zinc oxide nanoparticle coupled with dispersive liquid-liquid microextraction. Ultra-trace concentrations of brilliant green were dispersed to the organic phase in DLLME method after adding dispersive solvent and chitosan- zinc oxide nanoparticles. The experimental factors such as the amount of chitosan- zinc oxide nanoparticles, the concentration of Triton X- 114, type of volume of extraction and dispersive solvents, extraction time, rate and time of centrifugation, the volume of sample, and pH were investigated to order to enhance of the extraction efficiency. Under optimum extraction conditions, the volume of chloroform (as extraction solvent) and methanol (as dispersive solvent) were 100.0 µL and 550.0 µL, respectively; the amount of chitosan- zinc oxide nanoparticles was 15.0 mg; the time of extraction was 4.0 min; rate and time of centrifugation were 3000.0 rpm and 8.0 min, respectively, the volume of sample was 8.0 mL, and pH of the sample solution was 4.0. After optimizing the microextraction conditions and instrumental factors, an enrichment factor of 169.0 was achieved. The analytical curve (absorbance vs. concentration) was linear over the range 1.0-200.0 µg/L of brilliant green. The limit of detection and relative standard deviation were 0.3 µg/L and < 6.1 %, respectively. The protocol was successfully employed for the determination of brilliant green in the seawater of Chabahar Bay and fish (Sphyraena jello) samples.