Detection of 2,2′-Azobis(2-amidinopropane) Dihydrochloride in Polyvinylpyrrolidone by Capillary Electrophoresis with Field-Amplified Sample Injection

A sensitive method was developed for detecting 2,2′-azobis(2-amidinopropane) dihydrochloride in polyvinylpyrrolidone by capillary electrophoresis with indirect UV detection. The detection sensitivity was improved significantly using the field-amplified sample injection technique. The background electrolyte was composed of 25 mM imidazole-HCl solution (pH 4.0), in which imidazole acted as the cation probe for the indirect detection at UV 214 nm. Effects of the experimental parameters including pH, the concentration of imidazole as well as the sample injection time on sample preconcentration were investigated and optimized. Under the optimized conditions, baseline separation of 2,2′-azobis(2-amidinopropane) ion with other ions in the polyvinylpyrrolidone samples was achieved within 8 min. The RSD% for the repeatability of the migration time and the peak area were determined as 0.95% and 3.47%, respectively. The limit of detection (LOD, S / N  = 3) and the limit of quantitation (LOQ, S / N  = 10) were determined as 1.11 × 10 −5 M and 2.77 × 10 −5 M, respectively. The measured recovery at three concentration levels was in the range of 101–104%. This method was successfully applied to detect 2,2′-azobis(2-amidinopropane) in the commercial polyvinylpyrrolidone samples.