A microstructured capillary electrophoresis method for nitrocellulose detection in dynamite

• A microstructured capillary is employed to develop a method for dynamite analysis.
• Hydrodynamic studies are recommended to calculate real volumes injected.
• Method was developed in terms of derivatization and CE instrumental parameters.
• Nitrocellulose at pg levels was detected in dynamite samples.
• A real forensic application is demonstrated for future casework.

In this article, we present a microstructured capillary electrophoresis method for the determination of minimal amounts of nitrocellulose in dynamite samples. A 6-hole microstructured capillary (MSC) was selected for the method development. First, the hydrodynamic behaviour of the MSC was studied at varying lengths (31, 41 and 51 cm), which had never been studied before. Next, one of the MSC segments (31 cm) was employed to develop a microstructured capillary electrophoresis method to determine nitrocellulose in dynamite. In a first evaluation, the dynamite derivatization process was investigated to obtain an efficient derivatization yield. Afterward, the instrumental parameters, more specifically voltage and capillary cartridge temperature, were optimized. Afterward, the analytical performance of the developed methodology was assessed. Dynamite analyses during a period of 15 days were performed to establish intra-day (10 analyses) and inter-day (40 analyses) precision, obtaining RSDs lower than 6% and 10%, respectively. Besides, RSDs for migration time (< 0.5%), peak asymmetry (< 3%), resolution (< 3.9%), and S/N (< 9%) were obtained. Finally, a diluted sample of dynamite was analyzed, detecting amounts of nitrocellulose in the order of 220–400 pg.