70 
5.3.4.2 Consequences for results, this study 
The total response factor correction mode was developed at the end of this project. 
Therefore, most of the results are quantified by the approach of Tomy et al. (1997). The 
problem about the influence of chlorine content was well known from the beginning. 
Therefore, the reference standards were selected accordingly, and deviations between 
data calculated in either mode do not exceed the general measuring uncertainty 
between and within the applied measuring technique. 
5.3.5 Selection criteria for PCA quantification techniques 
Table 49 and Table 50 in the appendix give a survey about the applied analysis 
techniques for each sample. Most samples were analysed in the following sequence: 
• First analysis by EI-MS/MS to obtain the total PCA content. This methodology 
has the lowest detection limits. 
• Second analysis by a formula and congener group specific method. Since the 
detection limits are higher for this group specific technique, this part could only be 
carried out for well detectable quantities (ca. 10-20 ng/g for biota and 50 ng/g for 
sediments). 
• Usually ECNI-MS was applied for biota and CH2CI2/CH4-NICI for sediments 
due to much more interfering compounds and partly very low concentrations. 
CH2CI2/CH4-NICI is much more time consuming and was only applied, if absolutely 
necessary. 
• Due to new instrumentation with considerably lower detection limits and better 
robustness, the analysis of sediment was possible with ECNI from 2003-2004. 
The analysis of some samples was repeated to compare ECNI and CH4/CH2CI2- 
NICI further.