Comparative Study for the Analysis of Organic Gunshot Residues by Micellar Electrokinetic Chromatography

Abstract

ABSTRACT

This study was undertaken to separate three dinitrotoluene compounds using micellar electrokinetic chromatography (MEKC). The influences of a running buffer and sample matrices were investigated with respect to migration, efficiencies, peak shapes and resolution. In this work, three on-line sample preconcentration techniques, sweeping, high salt stacking, sweeping-high salt stacking were developed from MEKC using 25 mM phosphate at pH 7.5, 75 mM sodium dodecyl sulfate, 30 kV applied voltage, and on-column UV detection at 200 nm. High salt stacking had shown to be the most powerful tool for sample concentration and optimized concentration of NaCl was 150 mM which provided the best separation in terms of peak intensity and efficiency. The linear regression was greater than 0.995 (1.0 to 10.0 ??g/g). For spiked the sample at 5 ??g/g, the precision was ranging from 0.99 to 3.16 % relative standard deviation (RSD). Limit of detection was lower than 1.0 ??g/g. The mean recoveries were between 68.03 and 90.78%. The optimized high salt stacking procedure has been shown to be reliable, accurate and precise for monitoring of DNT in unburned gun powder.

Keywords: micellar electrokinetic chromatography (MEKC), dinitrotoluene (DNT), high salt

stacking, sweeping, sample matrix