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Environmental Engineering Research 1999;4(2): 135-142.
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BASELINE SEPARATION OF 2,4,6-TRINITROTOLUENE (TNT) AND ITS BIOTRANSFORMATION PRODUCTS USING HPLC: PRECAUTIONS FOR
ANALYTES LOSS
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Bumhan Bae1†, Robin, L. Autenrieth2, and James S. Bonner2 |
1Department of Civil Engineering, KyungWon University, Sungnam, Kyunggi 461-701, Korea 2Department of Civil Engineering, Texas A&M University College Station, TX77843-3136 |
Corresponding Author:
Bumhan Bae , |
Received: April 11, 1999; Accepted: June 6, 1999. |
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ABSTRACT |
Analysis of TNT and its metabolites using HPLC is a convenient and efficient method especially for samples from a biological origin. However, it is not always easy to separate the numerous intermediates, especially isomers of reduced TNT, and often be an obstacle for accurate and reliable analytical results. We are reporting a practical baseline separation of TNT and two intermediates, 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene, using isocratic elution of water and methanol on a C-8 column. The developed analytical method is simple but baseline separation of two isomers was possible with high accuracy.
Sample pretreatment was also important for the accurate anlaysis of TNT and its intermediates. Analyte loss on syringe filters during filtration was tested with nine commercial products including three kinds of PTFE filters, two PVDF filters, a polysulfone, a nylon, and a polycarbonate filter The loss of TNT was the greatest (>93.9%) on the PVDF filter, followed by polysulfone (>71.8%) and nylon (> 24.2%). The loss of TNT was statistically significant in all filtered samples with a 95% confidence limit. The same experiment was repeated using the supernatant of a TNT degrading aerobic bacterial culture resulting in an analyte loss for all the tested filters. The lowest analyte loss occurred for a PTFE filter, with the highest loss on the polysulfone filter. Analyte loss seems to depend on the filter and the specific analyte interactions such as hydrophobicity. Unaccounted for losses to filters used for sample pretreatment can result in an overestimation of transformation or introduce significant error for materials balance calculations.
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Keywords:
2.4.6-trinitrotoluene | baseline separation | HPLC | analyte loss |
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