76 
Table 20: Fractionation behaviour of the Florisil® clean-up for chlordane compounds carried out on two 
different batches. Relative recoveries [%] of the total amounts are given. Tetrachloro- (TCN), octachloro- 
naphthalene (OCN), the chlordane compound MC8 and 4,5-dichlorochlordene were evaluated as internal 
standards (ISTD). 
Compounds Column 1 Column 2 
Pre-fraction 
PCA-Fraction 
Pre-fraction 
PCA-Fraction 
ISTD 
13 Ci 0 -frani-Chlordane 
<1 
87 
<1 
95 
OCN 
<1 
107 
<1 
106 
TCN 
44 
56 
25 
49 
MC8 
5 
87 
<1 
109 
4,5 -Dichlorochlordene 
97 
9 
74 
<1 
Chlordanes 
frans-Chlordane 
5 
86 
<1 
99 
rz.v-Chlordane 
<1 
87 
<1 
91 
Fleptachlor 
105 
5 
55 
0 
rz.v-Nonachlor 
<1 
89 
1 
96 
frans-Nonachlor 
41 
47 
61 
28 
5.3.7.4 Blank controls 
Blanks were always equal to the detection limits due to a very stringent cleaning proce 
dure of glass ware (heating to 450 °C overnight, see experimental in the annex) and 
many safety measures such as separate glass ware, pretreatment of adsorbents at 600 °C 
etc. The blank problem is very serious for PCA analysis, but hardly addressed in the 
literature, which makes many data therein doubtful. 
5.3.7.5 Recoveries 
Chloroparaffins 
Recoveries of PCA in biota were checked for the whole extraction and clean-up method 
with spiked muscle tissue from mackerel. As can be seen from Table 21, recoveries 
were good for PCA and the internal standard.