138 
Gas chromatographic separations were carried out with an HP 5890II gas 
chromatograph (Hewlett Packard, Palo Alto, USA) equipped with a split/splitless 
injector and a capillary of 25 m length and 0.20 mm ID coated with a 0.33 pm film of 
HP-1 (100 % dimethylpolysiloxane, Hewlett Packard, Palo Alto, USA). A sample 
volume of 1 pi was injected in the splitless mode (splitless time 2 min). The injector 
temperature was 260 °C. He (99,999 %) was used as carrier gas at an inlet pressure of 
138 kPa. The temperature programme was as follows: 150 °C for 2 min, then with 
7 °C/min to 260 °C, isothermal for 8 min and finally with 10 °C/min to 280 °C, 
isothermal for 13 min. 
A VG Autospec (Micromass, Manchester, UK) mass spectrometer was employed in the 
ECNI-mode. Argon was applied as reagent gas at an ion source pressure of 2-10" 5 mbar. 
The mass resolution was 12'000 at an acceleration voltage of 6 kV. The ion source 
temperature was set to 170 °C, the filament current to 0.3-1 mA and the electron energy 
to 25-40 eV. Perfluorokerosene was used for mass calibration. The most abundant 
isotope signals of the [M-Cl]" ions were recorded in the selected ion mode for PC As, 
and [M]" or [M-4C1-2H]" ions for 1 ’Cio-/ra/7.v-chlordanc. The dwell time per ion was 
50 ms. 
5.6.7 Group pattern determination of PCAs by CH4/CH2CI2-NICI 
Gas chromatographic separations was carried out on an HP 5890II gas chromatograph 
(Hewlett Packard, Palo Alto, USA), equipped with a Hewlett Packard 7673 auto 
sampler. A fused silica capillary was employed of 15 m length and 0.25 mm ID coated 
with a 0.25 pm film of DB5-MS (5%-phenyl-95%-methylsiloxane, J&W Scientific, 
Folsom, USA). The injected volume was 1.5 pi in the splitless mode (2 min splitless 
time). The injector temperature was 275 °C. He was used as carrier gas (99,999 % 
purity, Carbagas, Switzerland) at a head pressure of 68,9 kPa (10 psi). The following 
temperature programme was employed: 100 °C isothermal for 2 min, with 10 °C/min to 
260 °C, isothermal for 10 min.