On-Line SPE Coupled with LC–APCI–MS for the Determination of Trace Explosives in Water

Abstract

In this study, a rapid, sensitive, and fully automated on-line solid phase extraction (SPE)-liquid chromatography (LC)-mass spectrometry (MS) method for the analysis of explosive residues in water, was systematically investigated. First, separation of explosive residues was achieved by reverse-phase chromatography using an XDB-C18 column in 30 min with an eluent containing 0.1% acetic acid, 5 mM ammonium acetate, and methanol. Secondly, atmospheric pressures chemical ionization (APCI) and electrospray ionization (ESI) interfaced with the MS detector were used to examine the explosive residues, indicating that APCI-MS was more suitable than ESI-MS for the detection of explosives. Thirdly, the conditions for on-line SPE, including solvent pH and sample injected volume, were optimized. The calibration curves obtained for all explosives studied were linear in the concentration range 0.5-50 lg L -1 . The detection limits of this method ranged from 0.05 to 0.5 lg L -1 when 4000 lL of sample was on-line pre-concentrated on C18 enrichment column. The recoveries from lake waters spiked with explosive standard solution ranged from 90.5 to 108.0%. The proposed method is simple, fast, and could be applied successfully to the analysis of explosive residues in contaminated water without any further pretreatment.

High-Throughput Trace Analysis of Explosives in Water by Laser Diode Thermal Desorption/Atmospheric Pressure Chemical Ionization-Tandem Mass Spectrometry

“…The detection performance of the present method is more than 100 times better than that of the standard LC-UV method (1−10 μg/L), 31 up to ∼17 times higher than that reported for an SPME-GC-MS (e.g., 0.325 μg/ L for RDX) 32 and up to ∼10 times higher than that reported recently for an SPE-APCI-LC-MS method (e.g., 0.5 μg/L for DNT and 0.1 μg/L for RDX). 33 The proposed method is applicable for the monitoring of explosives in water at trace levels, and our results confirm the quantification potential for concentrations generally found in natural and contaminated waters.…”

Rapid narrow band elution for on-line SPE using a novel solvent plug injection technique

“…The SPE method utilized for this purpose has been previously described [17], similar to numerous other examples for fast on-line SPE-HPLC or SPE-MS methods in the literature [18][19][20][21]. These approaches generally suffer from several drawbacks, including peak broadening from slow elution rates and problems arising from gradient delay [15,22,23] as outlined in the Introduction.…”

Developments in Explosives Characterization and Detection

“…Similarly, Mattarozzi and colleagues developed a novel diethoxydiphenylsilanebased coating for planar SPME and were able to achieve quantitation limits in the low nanogram level [70]. Liquid concentration methods, such as solid-phase extraction (SPE) [71][72][73] have also been widely used in the detection of explosives. In 2011, Sun et al [73] was able to use online SPE coupled to liquid chromatography mass spectrometry (LCMS) for the analysis of explosive residues in water [73].…”

“…Liquid concentration methods, such as solid-phase extraction (SPE) [71][72][73] have also been widely used in the detection of explosives. In 2011, Sun et al [73] was able to use online SPE coupled to liquid chromatography mass spectrometry (LCMS) for the analysis of explosive residues in water [73]. Their results showed detection limits ranged from 0.05 to 0.5 μg/L when 4000 μL of sample was preconcentrated onto the column.…”