Simple, fast, and simultaneous determination of orthophosphate, pyrophosphate, and tripolyphosphate by capillary electrophoresis with capacitively coupled contactless conductivity detection

Abstract

This work describes a novel analytical method using capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C⁴D) for simultaneous, simple, and rapid determination of three inorganic phosphates (orthophosphate, pyrophosphate, and tripolyphosphate) widely used as food additives and in pharmaceutical formulations. A background electrolyte composed of 0.5 mol L^-1 acetic acid provided fast separation (around 3.0 min) and good separation efficiency and peak resolution. Linearity in the concentration range of 10-500 mg L^-1 was confirmed by the coefficients of determination (R²) higher than 0.99. The limits of detection varied from 0.41 to 0.58 mg L^-1. The accuracy of the proposed method was assessed by recovery tests conducted at three concentration levels in tap water samples, food, and personal hygiene products. Recovery values varying from 81% to 118% were achieved, indicating an acceptable accuracy. The proposed CE-C⁴D successfully determined the three inorganic phosphates in the analyzed samples.

Keywords: electromigration; food additives; polyphosphates.