Capillary electrophoresis with capacitively coupled contactless conductivity detection applied to the quantitation and to the determination of physical-chemical properties of peroxycarboxylates in aqueous medium

• Published in: Electrophoresis Vol. 34; no. 14; pp. 2065 - 2071
• Main Authors: Vidal, Denis T. R., do Lago, Claudimir L.
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 01-07-2013
• Subjects: Calibration; Conductivity detection; Electric Conductivity; Electrophoresis; Electrophoresis, Capillary - methods; Equilibrium constant; Estimates; Fluid dynamics; Fluid flow; Formates - analysis; Hydration; Hydrodynamics; Kinetic constant; Limit of Detection; Monitors; Peracetic Acid - analysis; Peroxides - analysis; Peroxy acids; Propionates - analysis; Water - chemistry; Equilibrium constant; Kinetic constant; Conductivity detection; Peroxy acids
• ISSN: 0173-0835; 1522-2683
• DOI: 10.1002/elps.201300059

CE with C4D (CE‐C4D) was successfully applied to the investigation of performate, peracetate, and perpropionate in aqueous medium. Ionic mobilities, diffusion coefficients, and hydrodynamic radii were obtained for the first time for these species. CE‐C4D was also used to estimate the pKa values of the peroxycarboxylic acids. Because the peroxycarboxylates (POCs) undergoes hydrolysis while migrating, a simple calibration curve cannot be used for quantitation. Thus, an indirect calibration approach was used. The new method was used to monitor the formation of peroxycarboxylic acids from hydrogen peroxide and the carboxylic acid as well as to the quantitation of peracetic acid in a commercial sample. The CE‐C4D method compares favorably with the conventional titration method because of the possibility of speciation of the POC, the low sample consumption, and the low LOD (14, 8, and 24 μmol/L for performate, peracetate, and perpropionate, respectively). Although POCs are structural isomers of monoalkyl carbonates, they have greater hydrodynamic radii, which suggests that the positions of the oxygen atoms in the molecules have a direct impact in the charge density and consequently on the hydration atmosphere.