Analysis of ammonia and aliphatic amines in environmental water by micellar electrokinetic chromatography and QSPR modeling of electrophoretic migration time

In this paper, a rapid and sensitive method for the determination of ammonia and 22 aliphatic amines derivatized was established by cyclodextrin (CD) modified micellar electrokinetic chromatography with laser-induced fluorescence detection using 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole as a derived reagent. By a series of unvaried studies, the best conditions were selected using 20 mM tetraborate (pH 9.70) containing 25 mM SDS, 7 mM β-CD, 10% acetonitrile, 0.5 M urea, and applied voltage 25 kV. Under the optimum conditions, ammonia and 22 aliphatic amines were separated successfully in 19 min. The signal response was linear over three-order of concentrations. The intra-day and inter-day relative standard deviations (RSD) were less than 0.81% and 1.00% for migration times, 1.76% and 2.01% for peak areas. Limits of detection (LOD) for the analytes was (S/N = 3) approximate 10−9–10−12 M. The method was applied to the determination of ammonia and aliphatic amines in environmental water with recoveries in the range of 90.2–110.8%. In addition, a quantitative structure–property relationship (QSPR) model for the estimation of the electrophoretic migration time was established with the comprehensive descriptors for structural and statistical analysis (CODESSA) program for the first time. The multilinear regression (MLR) equation contained two theoretical descriptors and had the following statistical indices: R2 = 0.9668, F = 290.7839, Rcv2=0.9576 and S2 = 0.8149.