Distribution of Chlorinated Hydrocarbon Pesticides and PCBs in the ...

Fraction 2: beta-HCH, alpha-HCH (60%), gamma-HCH, dieldrin,
endrin, o,pt-DDT, o,pt-DDD and p,pt-DDD, alpha-
endosulphan, heptachlor epoxide, methoxychlor,
cis- and trans-chlorane.
Fraction 3: methoxychlor (lo%), dieldrin (5%).
Two composite pesticide standards and PCB standards
(Aroclor 1254 and/or 1:l Aroclor 1254/Aroclor 1260) were run
-
daily to verify instrument performance, establish current
retention times and determine current response factors.
Each sample fraction was injected in duplicate, and when
necessary co-injected with a pesticide composite standard
mixture.
Extracts from the third sampling trip were separated using
the following procedure as per Nordstrum and Muir (1985).
A glass column (10 mm x 240 mm) was filled with hexane and
slurry packed with florisil (8 g 1.2% water deactivated), capped
with a 10 mm layer of anhydrous sodium sulphate and flushed with
40 mL hexane. Fraction 2 from the gel permeation column was
quantitatively tr-ansferred to the column followed by a series of
rinses with 3 x 1 mL hexane. The column was eluted with 35 mL
hexane (fraction l), 34 mL 15% dichloromethane in hexane
(fraction 2) and 52 mL 50% dichloromethane in hexane (fraction
3). Each fraction was taken down to 2 mL by rotary evaporation
for analysis by GC/ECD.
Cut points for this procedure gave the following
separation:
Fraction 1:
Fraction 2:
hexachlorobenzene, heptachlor, aldrin, o,pt-DDE,
p,pt-DDE, Mirex, decachlorobiphenyl (I.S.)
alpha-, beta-, and gamma-hexachlorocyclohexane,
oxychlordane, trans- and cis-chlordane, o,pf-
DDD, p,pt-DDD, p,pt-DDT, cis-nonachlor