Rapid and simple analysis of trace levels of three explosives in soil by liquid chromatography—tandem mass spectrometry

Abstract

Summary. The analysis of trace levels of explosives in post-blast debris is critical in homeland security, environmental analysis, and crime scene forensic investigations. A fast and a selective determination method with high recovery was developed for the common explosives 2,4,6-trinitrotoluene (TNT), 3,5-trinitro-1,3,5-triazacyclohexane (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in soil, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). An easy and practical sample preparation method was developed using 4.00 mL acidified acetone with 0.25% HCl. After the easy evaporation of acetone extract, 10 min LC-MS/MS analysis provided a clear separation in column. Short duration of the whole procedure allows the use of this method in routine analysis. As a result of the analysis performed in spiked soils in 50.0, 100.0, and 250.0 ng g −1 concentrations, high recoveries such as 100.4 (±8.8)% for RDX, 96.9 (±10.5)% for HMX, and 97.6 (±13.9)% for TNT were obtained. Limit of detection (LOD) and limit of quantification (LOQ) values obtained from the analysis of the spiked soils were 4.3 ng g −1 and 7.00 ng g −1 for RDX, 6.8 ng g −1 and 10.0 ng g −1 for HMX, and 18.9 ng g −1 and 38.0 ng g −1 for TNT, respectively. The Horwitz Ratio (HorRat) calculation was used to evaluate if the inter-day and inter-analyst precisions were in the acceptable limits. The method was successfully applied to three artificial explosion samples for detection of explosives.

Basic principle of soft ionization mass spectrometry and development of ion source

“…Scientists propose ion-molecule reaction [18] to describe this process, but some anion adduction, such as analysis of HMX [19], may only rely on the attraction between electronegative material. In a word, there are force between adduct ion and analyte, and the force intensity between different adduct ion and analyte is different.…”

Basic principle of soft ionization mass spectrometry and development of ion source

“…Scientists propose ion-molecule reaction [19] to describe this process, but some anion adduction, such as analysis of HMX [20], may only rely on the attraction between electronegative material. In a word, there are force between adduct ion and analyte, and the force intensity between different adduct ion and analyte is different.…”

Basic principle from electrospray ionization to soft ionization mass spectrometry and development of ion source

“…Scientists propose ion-molecule reaction [30] to describe this process, but some anion adduction, for example, analysis of HMX [31], may only rely on the attraction between electronegative material. In a word, there are force between adduct ion and analyte, and the force intensity between different adduct ion and analyte is different.…”