Mixture design of an electrolyte system for the simultaneous separation of Cl - , SO 4 2- , NO 3 - , NO 2 - , and HCO 3 - in shrimp-farming water by CZE-UV.

Shrimp is one of the most traded fishery products in the world. The shrimp-farming water ionic composition is fundamental to the growth and survival of these specimens. Therefore, this study is aimed to develop a method for the simultaneous separation of Cl, SO, NO, NO, and HCO in this sample by capillary zone electrophoresis with UV indirect detection, without any prior sample treatment, besides dilution. The background electrolyte (BGE) was composed of CrO (60 mmol L), cetyltrimethylammonium bromide (CTAB, 2.5 mmol L), acetonitrile (0.875% (v/v)), and methanol (2.625% (v/v)). The mixture design optimized the BGE composition. Acetonitrile and methanol changed the degree of solvation of the anions, which decreased the radius, a phenomenon proven by calculating the radius of anions in all the conditions of the mixture design. The optimized and validated method allowed the simultaneous determination of the five above-mentioned anions in 10 min.