Rapid Identification of Picric Acid in Explosion Cases by Gas Chromatography£­Triple Quadrupole Mass Spectrometry

KeyWord:picric acid  organic explosives  methylation derivatization  gas chromatography-triple quadrupole mass spectrometry

Abstract:

      Based on that the current derivative method for picric acid£¨TNP£© using sodium hypochlorite may result in possible false positive in forensic science identification£¬a gas chromatography£­triple quadrupole mass spectrometry£¨GC£­TQMS£© with TNP methylation derivatization method was established for the highly sensitive detection of TNP in this paper£®TNP was converted into 2£¬4£¬6-trinitroanisole£¨TNA£© via a methylation reaction using trimethyl orthoformate£¨TMOF£© as reagent£®Under the optimized methylation derivatization conditions£¬sample solution was firstly dehydrated and put into a liner pipe£¬then 100 ¦ÌL of TMOF were added£®The mixture was heating at 95 ¡æ for 70 min£¬and the reactant was analyzed after cooling down and being filtered£®The detection effects of GC£­TQMS in EI mode and NCI mode were compared£®The limits of detection were 1.33 ¦Ìg/L and 5.02 ¦Ìg/L in EI and NCI mode£¬respectively£®The detection performance of this method for the mixed organic explosives in soil was also investigated£®Five kinds of organic explosives were successfully detected£®The spiked recoveries for soil sample were 84.0%£¬with a relative standard deviation£¨RSD£© of 4.6%£®Results showed that the four common nitroaromatic organic explosives investigated had no interference with this method. The method is simple£¬rapid£¬sensitive and selective£¬and it offers a considerable improvement in identifying the picric acid in explosive mixtures£¬which meets the needs of forensic science identification and could be used for the detection of trace TNP in actual cases.