Organic compounds in sludges 235
selected ion-monitoring mode to provide maximum sensitivity and precision. This
technique has been used in similar work on polychlorinated napthalenes. Ten ions
were selected for monitoring: one from the parent cluster for each of the chlorinated
biphenyls (C 12 H 9 C1 to C 12 C1 10 ). PCBs were quantitated using anthracene as external
standard and a previously determined relative molar response (anthracene parent ion
mass 178; 27 ng mL
−1 ).
The retention time results for 34 chlorinated compounds found in sewage covered a wide range between chlorobenzenes (Rf 0.5–3) chloroanilines (Rf 1.2–44),
chlorophenols Rfs 3.7–5.17, mono, di and penta chlorobiphenyls (Rf 6.3–11.1),
dichlorbenzophenones (Rf 9.2) and DDE Rf 8.6–15.0).
Gutierrez et al [172] give an account of an investigation to compare packedcolumn gas chromatography, capillary column gas chromatography and capillary
column gas chromatography-mass spectrometry techniques in the analysis of complex sewage sludge samples for polychlorinated biphenyls and the organochlorine
insecticides gamma-HCH, Aldrin, Dieldrin and Endrin. The results were found to
differ among the three methods. It was concluded that capillary column gas chromatography was the best method of analysing these residues in complex sewage
samples.
10.7.2 Carbamate insecticides and fungicides
A high performance liquid chromatographic procedure [175] has been described for the
simultaneous determination of the fungicides sodium-N-methyldithiocarbamate and
methylisothiocyanate in surface waters and in sewage based on their separation on a
reversed phase column with a miscellar mobile phase (hexadecyltrimethylammonium
bromide) in 1:1 v/v methanol; water buffered to pH6.8. Detection limits were 70 and
1 µg dm
−1 when the analysis was performed with an ultraviolet detector at 247 nm.
10.7.3 Organophosphorus insecticides
This layer chromatography has been applied to the determination of Abate residues
in water [176]. The sample of surface water or sewage, acidified with sulphuric acid,
was extracted with chloroform. The extract was evaporated under nitrogen at 60–
70
◦ C and the residue was dissolved in acetone. This solution was analysed by thinlayer chromatography. Detection was by exposure of the plate to bromine vapour and
spraying with 1% N-dimethyl-p-(phenylazo)aniline (C1 solvent yellow 2) solution in
95% isopropyl alcohol. Abate gave distinct red spots (R, 0.11 ± 0.01) on a bright
yellow background. Spot areas were related to concentration by a calibration graph.
Down to 9 µg of Abate could readily be determined.
An official method [177] describes procedure for the analysis of organophosphorus insecticides in sewage sludge. The method includes a primary extraction-gas
chromatographic procedure for the analysis of sewage sludge and a confirmatory thin
layer chromatography procedure for organophosphorus pesticides in sludges, the latter
being capable of 80% recovery of Malathion and Ethyl Parathion and 70% recovery
of Diazinon, with analytical limits of detection from 4.0 to 8.0 µg per kg for these
three compounds.
selected ion-monitoring mode to provide maximum sensitivity and precision. This
technique has been used in similar work on polychlorinated napthalenes. Ten ions
were selected for monitoring: one from the parent cluster for each of the chlorinated
biphenyls (C 12 H 9 C1 to C 12 C1 10 ). PCBs were quantitated using anthracene as external
standard and a previously determined relative molar response (anthracene parent ion
mass 178; 27 ng mL
−1 ).
The retention time results for 34 chlorinated compounds found in sewage covered a wide range between chlorobenzenes (Rf 0.5–3) chloroanilines (Rf 1.2–44),
chlorophenols Rfs 3.7–5.17, mono, di and penta chlorobiphenyls (Rf 6.3–11.1),
dichlorbenzophenones (Rf 9.2) and DDE Rf 8.6–15.0).
Gutierrez et al [172] give an account of an investigation to compare packedcolumn gas chromatography, capillary column gas chromatography and capillary
column gas chromatography-mass spectrometry techniques in the analysis of complex sewage sludge samples for polychlorinated biphenyls and the organochlorine
insecticides gamma-HCH, Aldrin, Dieldrin and Endrin. The results were found to
differ among the three methods. It was concluded that capillary column gas chromatography was the best method of analysing these residues in complex sewage
samples.
10.7.2 Carbamate insecticides and fungicides
A high performance liquid chromatographic procedure [175] has been described for the
simultaneous determination of the fungicides sodium-N-methyldithiocarbamate and
methylisothiocyanate in surface waters and in sewage based on their separation on a
reversed phase column with a miscellar mobile phase (hexadecyltrimethylammonium
bromide) in 1:1 v/v methanol; water buffered to pH6.8. Detection limits were 70 and
1 µg dm
−1 when the analysis was performed with an ultraviolet detector at 247 nm.
10.7.3 Organophosphorus insecticides
This layer chromatography has been applied to the determination of Abate residues
in water [176]. The sample of surface water or sewage, acidified with sulphuric acid,
was extracted with chloroform. The extract was evaporated under nitrogen at 60–
70
◦ C and the residue was dissolved in acetone. This solution was analysed by thinlayer chromatography. Detection was by exposure of the plate to bromine vapour and
spraying with 1% N-dimethyl-p-(phenylazo)aniline (C1 solvent yellow 2) solution in
95% isopropyl alcohol. Abate gave distinct red spots (R, 0.11 ± 0.01) on a bright
yellow background. Spot areas were related to concentration by a calibration graph.
Down to 9 µg of Abate could readily be determined.
An official method [177] describes procedure for the analysis of organophosphorus insecticides in sewage sludge. The method includes a primary extraction-gas
chromatographic procedure for the analysis of sewage sludge and a confirmatory thin
layer chromatography procedure for organophosphorus pesticides in sludges, the latter
being capable of 80% recovery of Malathion and Ethyl Parathion and 70% recovery
of Diazinon, with analytical limits of detection from 4.0 to 8.0 µg per kg for these
three compounds.