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

This work describes a novel analytical method using capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (CD) 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 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 was confirmed by the coefficients of determination (R) higher than 0.99. The limits of detection varied from 0.41 to 0.58 mg L. 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-CD successfully determined the three inorganic phosphates in the analyzed samples.