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6.3.2.3 Methods for Pentachlorophenol and Trichloropyridinol 
PCP and TCPy are susceptible to adsorption in the GC system because of their polar 
phenolic substructure. Direct GC analysis was only possible at high concentrations 
(>lng). Therefore, two alternative approaches were applied during the study. 
First, an HPLC-MS method was developed in order to overcome thermal stress during 
the analysis. This was successful in principle. A reversed phase HPLC gradient 
separation yielded well-defined, non-tailing peaks both for PCP and TCPy, and ESI MS 
showed M-l ions in the negative ionisation mode with a good ion yield (Figure 52, 
Appendix 6.6.6.1). Unfortunately, it was not possible to fragment the pseudo-molecular 
ion; the high selectivity of MS-MS thus could not be used, but only the less selective 
single-stage MS in SIM mode. Consequently, this method was applicable only to water 
samples, where matrix disturbances are much less pronounced than in sediment or biota 
samples. But even with water samples only a moderate sensitivity could be obtained. 
The second approach used a derivatisation step with heptafluorobutyric acid anhydrate 
(HFBAA) to form the HFBA esters and a GC-MS analysis in the NCI mode. This 
technique was used for sediments and biota. Only PCP could be derivatised and 
analysed by this method.