Organic compounds in sludges 225
copper (II)-fulvic acid complexes. Solution spectra yielded more structural information
on the complexes than did solid state spectra. It was concluded that undegraded anionic
surfactants in sewage sludge did not participate as isolated, independent ligands, but
may participate as co-ligands with other oxygen-containing functional groups, or as
moieties incorporated into the fulvic acid structure.
Differential pulse polarography
Hart et al [67] have described an indirect polarographic method for determining linear
alkylbenzene sulphonates in sewage and potable water. The method is reliable for
concentrations of 0.5 µg l
−1 or more. In this procedure the sample was nitrated with
fuming nitric acid, then adjusted to pH 12 and polarographed. All of the sewage
samples gave a reduction peak that occurred at the same potential as for the nitro
derivative of 4-phenyldodecane sulphonate, i.e. 0.74 V.
The polarographic method was found to be suitable for the determination of linear
alkylbenzene sulphonate with reasonable specificity.
In general, the methylene blue spectrophotometric method gave higher results,
probably because the methylene blue procedure give a total anionic surfactant content,
the so-called MBAS value (methylene blue active substances), whereas only surfactant
species or other organic compounds with a benzene ring would be likely to interfere
in the polarographic method. Even then the E p values of the derivatives of the species
would not necessarily coincide with those of linear alkylbenzene sulphonates nitro
derivatives.
10.2.5.3 Non-ionic detergents
Gas chromatography
Santos et al [70] used a gas chromatography-mass spectrometry to monitor levels
of di(2-ethylhexyl)phthalate, nonyl phenol, nonyl phenol ethoxylates and polychlorinated byphenyls in anaerobic and aerobic sewage sludge.
High performance liquid chromatography
Various workers have applied column chromatographic techniques to the determination of non-ionic detergents in sludges [71–73].
Applying this technique to the determination of alkylphenol mono and diethoxylates and alkyl phenols in sewage sludge Abel and Giger et al [71,72] obtained
recoveries exceeding 80% with relative standard deviation better than 8% and a
detection limit of 0.5 µg L
−1 . The same workers studied the determination of alkylphenol polyethoxylates in sewage and sewage sludge. In this procedure alkylphenol
polyethoxylates in wastewater samples were stripped into ethyl acetate. Normal
high-performance liquid chromatography phase using bonded phase aluminium silicate columns separated alkylphenol polyethoxylates and allowed their quantification.
Alkylphenol ethoxylates were selectively determined by absorption at 277 nm. Relative
deviations were 2–10% for major oligomers. Limits of detection for individuals were
estimated at 1 µg per litre. Total recovery of alkylphenol polyethoxylates was 87%.
Reverse-phase high-performance liquid chromatography was used to determine alkyl
substituents and as a rapid screening method. Combined normal and reverse phase
copper (II)-fulvic acid complexes. Solution spectra yielded more structural information
on the complexes than did solid state spectra. It was concluded that undegraded anionic
surfactants in sewage sludge did not participate as isolated, independent ligands, but
may participate as co-ligands with other oxygen-containing functional groups, or as
moieties incorporated into the fulvic acid structure.
Differential pulse polarography
Hart et al [67] have described an indirect polarographic method for determining linear
alkylbenzene sulphonates in sewage and potable water. The method is reliable for
concentrations of 0.5 µg l
−1 or more. In this procedure the sample was nitrated with
fuming nitric acid, then adjusted to pH 12 and polarographed. All of the sewage
samples gave a reduction peak that occurred at the same potential as for the nitro
derivative of 4-phenyldodecane sulphonate, i.e. 0.74 V.
The polarographic method was found to be suitable for the determination of linear
alkylbenzene sulphonate with reasonable specificity.
In general, the methylene blue spectrophotometric method gave higher results,
probably because the methylene blue procedure give a total anionic surfactant content,
the so-called MBAS value (methylene blue active substances), whereas only surfactant
species or other organic compounds with a benzene ring would be likely to interfere
in the polarographic method. Even then the E p values of the derivatives of the species
would not necessarily coincide with those of linear alkylbenzene sulphonates nitro
derivatives.
10.2.5.3 Non-ionic detergents
Gas chromatography
Santos et al [70] used a gas chromatography-mass spectrometry to monitor levels
of di(2-ethylhexyl)phthalate, nonyl phenol, nonyl phenol ethoxylates and polychlorinated byphenyls in anaerobic and aerobic sewage sludge.
High performance liquid chromatography
Various workers have applied column chromatographic techniques to the determination of non-ionic detergents in sludges [71–73].
Applying this technique to the determination of alkylphenol mono and diethoxylates and alkyl phenols in sewage sludge Abel and Giger et al [71,72] obtained
recoveries exceeding 80% with relative standard deviation better than 8% and a
detection limit of 0.5 µg L
−1 . The same workers studied the determination of alkylphenol polyethoxylates in sewage and sewage sludge. In this procedure alkylphenol
polyethoxylates in wastewater samples were stripped into ethyl acetate. Normal
high-performance liquid chromatography phase using bonded phase aluminium silicate columns separated alkylphenol polyethoxylates and allowed their quantification.
Alkylphenol ethoxylates were selectively determined by absorption at 277 nm. Relative
deviations were 2–10% for major oligomers. Limits of detection for individuals were
estimated at 1 µg per litre. Total recovery of alkylphenol polyethoxylates was 87%.
Reverse-phase high-performance liquid chromatography was used to determine alkyl
substituents and as a rapid screening method. Combined normal and reverse phase