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2.1.4 Method development for PCA analysis 
The aim of the project was to develop new methods for the determination of PCAs in 
fish and sediments. They should allow a low cost screening and a less complex 
determination of formula and congener group patterns. Therefore, the mass 
spectrometric techniques described below were developed or improved during this 
project and a full method validation and intercomparison was carried out. The were used 
to determine PCA concentrations in fish from the North and Baltic Sea as well as from 
selected sites from the northern North Atlantic to obtain such information for the first 
time. 
Negative ion chemical ionisation (NICI) with CH2CI2/CH4: This technique suppressed 
strongly interferences from other polychlorinated pollutants, allows even the detection 
of low chlorinated PCAs and makes the use of low resolution MS possible. Moreover, 
response factors are quite uniform and independent from the degree of chlorination. The 
only disadvantage is the limited number of analyses possible, before the mass 
spectrometer has to be cleaned. 
Electron ionisation combined with MS/MS: Further fragmentation of fragment ions in 
common for all PCAs allow the determination of total PCAs with low cost 
instrumentation such as an ion trap MS (€ 60'000) with very high selectivity and 
detection limits comparable to high resolution mass spectrometry. Response factor 
differences are eliminated. The only disadvantage is the missing differentiation between 
sPCA and mPCA and that formula/ congener group specific results are not obtained. 
The technique has even lower detection limits using more expensive triple quadrupole 
MS. 
Optimisation of quantification by ECNI: Response factors depend strongly on the 
degree of chlorination of PCAs and mass overlap between formula/congener groups 
occur with low resolution MS. However, methods could be developed which 
compensated the influence of the degree of chlorination and which allowed eliminating 
mass overlap interferences by a careful retention time range selection and isotope ratio 
control of registered masses. This enabled the use of low resolution MS.