grab samples

Fraction 2 - I OO-ml mixture of6% diethyl ether in petroleum ether;
Fraction 3 - 150-ml mixture of 15% diethyl ether in petroleum ether;
Fraction 4 - I OO-mlof 50% mixture diethyl ether in petroleum ether (all at a flow rate of"'" 2 ml/ min).
Note: Large quantities of sulphur are often present in nearshore sediment dredge samples. The Fraction I
group should be treated with elemental mercury to remove the sulphur as mercuric sulphide before gas
chromatographic analysis. See Method I above for details.
Fraction I - PCB's and most of the DOE
Fraction 2 - Lindane, Heptachlor Expoxide, DOD, Methoxychlor, DDT, cis and trans Chlordane
Fraction 3 - Endrin and Dieldrin, a-Endosulfan
Fraction 4 - {3-Endosulfan
Note: The contents of each fraction will vary depending on a variety of circumstances. The compounds
listed for each fraction should serve only as a guide and should not be considered absolute.
(II) Each fraction should be separately collected, concentrated to 1- 2ml volume, transferred to 10ml
volumetric flask and made up to volume with benzene.
Chromatograph Column - 122. X 0.4 cm glass column packed with 5% QF-I on Chromosorb W-HP
80 -100 mesh.
Carrier gas of95% argon/ 5% methane (25 ml/min)
Oven 210°C
Injection port 235°C
Detector 265°C
References
CHOt, W. W., AND K. Y. CHEN. 1976. Associations of chlorinated hydrocarbons with fine particles and humic substances in nearshore
surfieal sediments. Enviro n. Sci. Tech. 10: 782-786.
CONFIRMATION OF IDENTITY OF RESIDUES
A. Organochlorine Pesticides
The retention time of organochlorine pesticides on one gas chromatographic column is insufficient
evidence for confirmation. Besides using a second column for confirmation, chemical confirmatory tests
may also be used and are especially important where PCB's and DDT group pesticides are suspected. A
dehydrochlorination procedure followed by oxidation is the preferred treatment method (Trotter 1975)
whereby the DDT group pesticides are converted to the corresponding benzophenones and the PCB's are
left intact. Separation of these components is effected on a Florisil column, after which they may be
confirmed by GC retention times and quantified as total DDT-type residues.
B. PCB's
Quantification can be achieved by comparison of the tOlal height of two or four large components of
an ArocJor 1254 standard GLC pattern with the corresponding peaks from the environmental samples and
from the sample subjected to perchlorination to decachlorobiphenyl. Although many PCB's may be
present, ArocJor 1254 most closely resem bles the G LC characteristics of the PCB's found in sediments to
date (based on Berg et al. 1972). (However, see also Webb and McCall 1973.)
C. General
There may be occasions where an uncommon unknown is being dealt with or it is essential to have the
best evidence possible on the identity of certain compounds present in a sediment sample. In such cases,
additional confirmation can be obtained using a technique such as mass spectrometry.
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