Agilent Analysis of TNT RDX CL-20 by APCI LC/MS/MS Application Note
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1. NOTICE Varian Inc was acquired by Agilent Technologies in May 2010 This document is provided as a courtesy but is no longer kept current and thus will contain historical references to Varian For more information go to www agilent com chem oft Agilent Technologies Application Note Number 18 April 2004 Analysis of TNT RDX and CL 20 by APCI LC MS MS A Colorado Varian Inc Introduction The detection and characterization of explosives has gained the interest of various analytical laboratories and research groups around the world For the forensic community trace analysis of explosive residues after arson and terrorism is of critical interest Biologists and environmentalists monitor biotransformation of these high energy compounds when evaluating environmental contamination Other groups such as the munitions industry continue to explore the synthesis of novel explosive materials In all of these examples investigators need an analytical methodology that is informative sensitive and selective as well as robust In this application note LC negative ion APCI MS MS is used to characterize and detect trinitrotoluene TNT hexahydro 1 3 5 trinitro 1 3 5 triazine RDX and 2 4 6 8 10 12 hexanitro 2 4 6 8 10 12 hexaazaisowurtzitane CL 20 Figure 1 Instrumentation e Varian ProStar 430 AutoSampler e Varian ProStar 210 Isocratic Solvent Delivery Module e Varian 1200L LC MS with APCI source HPLC Co2. While 10 ppb was the lowest calibration point Figure 6 single digit ppb levels can be easily attained with further optimization of ion source conditions Figure 7 The benefits of MS MS are readily observable as the concentration of the explosives decrease For example a 1 ppb injection of CL 20 in SIM mode is not as discernable when compared to the MS MS ion chromatogram at the same concentration Figure 8 Calibration Curves for Analyzed Explosives Figure 6 Good linearity was achieved for all compounds over a concentration of 10 ppb to 500 ppb LC MS Application Note 18 3 of 3 LOD Study of Explosives Mix TNT APCI SRM 257 0 gt 46 0 6 0eV RDX CL 20 1 2 3 4 5 iii Figure 7 With a 1 ppb injection of explosives mix TNT and RDX were at the LOD while the LOD for CL 20 could be significantly lower Comparison of SIM vs MS MS SIM Mode CL 20 APCI SRM 473 0 gt 154 0 6 0 eV MS MS Mode CL 20 1 2 3 4 5 minutes Figure 8 With a 1 ppb injection baseline noise obscures the CL 20 peak in the SIM mode while an excellent signal to noise is achieved with MS MS Conclusion APCI MS MS is effective in the determination of explosives The addition of an organochloro compound significantly enhances the detection limits of RDX and CL 20 through adduct ion formation The added selectivity of MS MS ensures reliable analysis of these compounds especially at trace concentrations These
3. a loss of 319 mass units C H OgNj Unlike TNT and CL 20 the RDX chlorine adduct ion dissociates mainly to yield NO7 fragment ions Figure 4 All three explosives eluted in less than 5 minutes under isocratic conditions Figure 5 TNT and RDX were well separated while CL 20 eluted close to TNT MS MS however adds an additional selective dimension by further separating the analytes according to their unique product ions The table on page one shows the MS MS transitions and retentions times for this analysis MS MS Spectrum for TNT 209 8 50 100 150 200 250 Figure 2 TNT dissociates two produce two intense product ions LC MS Application Note 18 2 of 3 MS MS Spectrum for CL 20 153 7 232 7 319 CL 20 Cl35 472 9 135 9 326 9 389 3 4224 473 9 iJ k h rf 3 2864 S a a a ee ce ce ee ec eo ee ee Figure 3 CL 20 chloride adduct also dissociates to produce two intense ions MS MS Spectrum for RDX NO 46 1 RDX CI35 256 8 31 6 ait 81 8 108 6 ial Ke 628 e S asa m7 1972 7284 2783 2973 m aa oe i i e i 50 100 150 200 250 300 Figure 4 RDX chloride adduct only yields one small product ion lon Chromatograms for Analyzed Explosives APCI SRM 227 0 gt 210 0 8 0 eV TNT APCI SRM 257 0 gt 46 0 6 0 eV RDX APCI SRM 473 0 gt 154 0 6 0 eV CL 20 ee 1 2 3 4 5 minutes Figure 5 500 ppb injection of the mix of explosives www varilanine com
4. data represent typical results For further information contact your local Varian Sales Office www varianine com
5. nditions MS Parameters APCI Torch Temp 450 C API Drying Gas 15 psi at 300 C API Nebulizing Gas 60 psi Corona Current 5 pA Capillary 40V Housing 50 C Collision Gas 1 7 mTorr Argon Compound Structures O N NO NO TNT No ON N EN gre N N ONS NO NS N ON NO on NO i RDX CL 20 Figure 1 Structure of analyzed explosives Column Pursuit C18 5 um 150 x 4 mm Varian Part No 2000 150X40 Mobile Phase water isopropanol methanol at 60 30 10 MS MS Scan Parameters and 0 1 chloroform isocratic Precursor Product Collision Retention Flow 0 8 mL min lon lon Energy Time Injection Volume 20 pL Analyte m z m z V min TNT 227 210 8 4 6 RDX 257 46 6 2 6 CL 20 473 154 6 4 2 LC MS Application Note 18 1 of 3 www varianine com Results and Discussion TNT a nitroaromatic readily undergoes charge exchange to create a radical anion in the source Unfortunately the chemical structures of RDX and CL 20 do not make them easily amenable to atmospheric pressure ionization without the aid of additives For this analysis chloroform was used as a source of chlorine for adduct ion formation TNT collisionally dissociates through two main fragmentation pathways Figure 2 One pathway is the loss of 17 u OH producing a fragment at m z 210 In the second pathway TNT loses an NO functional group to yield a product ion at m z 197 CL 20 also yields two intense product ions Figure 3 The major product ion is m z 154 or
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Agilent Analysis of TNT RDX CL 20 by APCI LC/MS/MS Application Note