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Title of article :
Determination of Nitroaromatic Compounds in Air Samples at Femtogram Level Using C18 Membrane Sampling and On-Line Extraction with LC-MS
Author/Authors :
Carlsson، H. نويسنده , , S?nchez، C. نويسنده , , Colmsj?، A. نويسنده , , Crescenzi، C. نويسنده , , Batlle، R. نويسنده ,
Issue Information :
دوهفته نامه با شماره پیاپی سال 2003
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Abstract :
This paper explores the use of C18 solid-phase extraction membranes for sampling very low concentrations of nitroaromatic compounds in the atmosphere. After sampling, analytes trapped in the membrane are desorbed online directly by a chromatographic mobile phase. The analytes are then separated onto a porous graphitic carbon (PGC) HPLC column. Finally, they are analyzed by an LC-MS/MS detector equipped with an atmospheric pressure chemical ionization (APCI) interface. The method was validated by controlled exposure of the membranes to standard gaseous mixtures of 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (2,4-DNT). The developed method was fully characterized, and no breakthrough was observed when sampling volumes up to 9.2 m3. Analyses of membranes following medium- and long-term storage demonstrated that samples could be stored on the C18 membranes without degradation or losses. In addition, the results obtained with this technique were compared with those obtained by a gas chromatographic method in which analytes were collected on Tenax TA and thermally desorbed. The developed method allows sampling at flow rates of 15 L/min and has method detection limits in the femtogram/liter range, with a relative standard deviation lower than 10%. An additional advantage of this method is that it separates most of the TNT and DNT isomers, as demonstrated by applying the method to the analysis of headspace over military-grade TNT explosives.
Keywords :
Field margins , Crop yields , Yield gains , Shelterbelts , Hedges
Journal title :
Analytical Chemistry
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