Simultaneous separation and determination of five organic acids in beverages and fruits by capillary electrophoresis using diamino moiety functionalized silica nanoparticles as pseudostationary phase

A kind of novel diamino moiety functionalized silica nanoparticles with the diameter of ∼110 nm was successfully prepared and characterised by transmission electron microscope (TEM) and elemental analysis. Capillary electrophoresis (CE) with this kind of nanoparticles as pseudostationary phase was developed for the simultaneous analysis of five organic acids in beverage and fruit samples. The effects of pH, buffer concentration, and nanoparticles concentration on separation were carefully investigated. Five organic acids were baseline separated in 5 min under optimum experimental conditions. The precisions for five replicate separations of a standard mixture solution were 2.71–6.13% for peak area and 1.22–1.93% for migration time respectively. The detection limits were 7.5, 0.15, 0.23, 0.33 and 10.0 mg/L for citric acid, salicylic acid, benzoic acid, sorbic acid and ascorbic acid, respectively. The developed method was applied to the simultaneous analysis of five analytes in beverage and fruit samples and certified reference materials with satisfactory results.