133 
Lipid removal was carried out with a glass column (length 30.0 cm, ID 2.0 cm) filled 
from bottom to top as follows: 1 g of water-free sodium sulphate, 40 g of a mixture of 
silica gel/conc. sulphuric acid (44 % (weight) of cone. H2SO4) and 1 g of water-free 
sodium sulphate again. The system was conditioned with 60 ml of 
77-hcxanc/dichloromcthanc (1+1, v/v). A pressure of 96.5 hPa was applied with a 
membrane pump (Elite 801, Hagen, Köln, Germany, flow 1.3 1/min). The sample was 
transferred to the top of the column and eluted under pressure with totally 130 ml of 
77-hcxanc/dichloromcthanc (1 + 1, v/v). The solution was concentrated to ca. 150 pi with 
a Turbo Vap, 10 ml of 77-hexane were added twice followed by a volume reduction to 
ca. 200 pi. 
Interfering compounds were removed by column chromatography on a glass column 
(length 30 cm, ID 1.5 cm) filled with (bottom to top): 1 g of water-free sodium sulphate, 
16 g of Florisil® (deactivated with 1.5 % water, 60-100 mesh, Fluka, Buchs, 
Switzerland) and 1 g of water-free sodium sulphate. Conditioning was carried out with 
30 ml of 77-hexane. After transfer of the sample, the pre-fraction was eluted with 60 ml 
of 77-hexane followed by 7 ml of dichloromethane. The fraction containing PCA was 
eluted with 60 ml of dichloromethane and concentrated to ca. 100 pi with a Turbo Vap. 
20 ml of cyclohexane were added and the volume reduced again to 100 pi. The sample 
was ready for quantification after addition of 10 ng of the recovery standard e-HCH 
(dissolved in 10 pi of cyclohexane). 
5.6.4 Clean-up procedure for sediments (PCAs and chlordanes) 
Sediments were dried at room temperature for 10 days (open-air, fume hood) and sieved 
with 2 mm mesh size. Depending on the TOC content, 2-50 g sediment were taken, and 
10 pi of a solution containing 1 ’C1 o-//Y/77.s'-ch lordane and octachloronaphthalene in 
cyclohexane (concentration of 1 ng/pl each) were added as internal standards. The dried 
sediment was filled into a pre-cleaned Soxhlet thimble (heated to 300 °C for 6 h, made 
from glass fibres, 30 mm diameter, 100 mm length, Schleicher&Schiill, Germany). 
Elemental sulphur was removed with activated copper powder (230 mesh, Merck, 
Germany; activated with concentrated nitric acid) during the Soxhlet extraction. Soxhlet