Jämförelse av metoder för TNT-bestämning i sediment
Publish date: 2003-01-01
Report number: FOI-R--0796--SE
Written in: Swedish
Dumped ammunition in lake and sea sediment is considered as an environmental problem. Consequently, accurate analytical methods for determination of explosives are needed for the correct assessment of distribution, transformation and effects in different environments. In this study three analytical methods have been tested for the determination of 2,4,6-trinitrotoluene (TNT) in 12 contaminated sediment samples from Skredsvik on the Swedish west coast. The first analytical method is a field screening method based on colorimetry where the carbanion of acetone reacts with TNT to form its Janowski complex with absorption maxima at 540 nm. The other methods are based on liquid chromatography coupled to ultraviolet detection (HPLC/UV) and gas chromatography coupled to mass spectrometry (GC/MS), respectively. The analytical results showed undetectable or very low concentrations in the range 10-200 ng g-1 dw (dry weight). Only the GC/MS method was sufficiently sensitive. The limits of detection were approximately 250 ng g-1 dw for HPLC/UV and approximately 2000 ng g-1 dw for the colorimetric method. Furthermore, the specificity of GC/MS was superior compared to the other methods. It was further shown that extraction with Soxhlet and liquid/liquid extraction resulted in better recoveries and higher sensitivity.