44 Organic compounds in soils, sediments & sludges
the industrial accident at Sevesco, Italy. Detection thresholds of 2–50 ppt were achieved
for agricultural soil samples.
2.8 MISCELLANEOUS ORGANIC COMPOUNDS
2.8.1 Humic and fulvic acids
Weber and Wilson et al [274] used anion and cation exchange resins to isolate fulvic
and humic acids from soil and water.
Ion-selective electrodes have been used to determine the stability constants for the
complexation of copper II ions with soil fulvic acids [275]. Two cases of binding sites
were found with conditional stability constants of about 1 × 10
6 and 8 × 10
3 .
Saar and Weber et al [276] compared methods based on spectrofluorimetry and
ion-selective electrode potentiometry for determining the complexes formed between
fulvic acid and heavy metal ions. The fluorescence properties of two fulvic acids, one
derived from the soil and the other from river water, were studied. The maximum
emission intensity occurred at 445–450 nm upon excitation at 350 nm, and the intensity varied with pH, reaching a maximum at pH 5.0 and decreasing rapidly as the pH
dropped below 4. Neither oxygen nor electrolyte concentration affected the fluorescence of the fulvic acid derived from the soil. Complexes of fulvic acid with copper,
lead, cobalt, nickel and manganese were examined and it was found that bound copper II ions quench fulvic acid fluorescence. Ion-selective electrode potentiometry was
used to demonstrate the close relationship between fluorescence quenching and fulvic
acid complexation of cupric ions. It is suggested that fluorescence and ion-selective
electrode analysis may not be measuring the same complexation phenomenon in the
cases of nickel and cobalt complexes with fulvic acid.
Wilson et al [277] carried out a compositional and solid-state nuclear magnetic
resonance (NMR) spectroscopic study of humic and fulvic acid and fractions present
in soil organic matter. The
13 C NMR study utilised cross polarisation-magic angle
spinning (CP-MAS) with spin counting. The elemental and functional group analyses
provided input for a series of analytical constraints calculations that yield an absolute
upper limit for the amount of aromatic carbon, and most probable estimates for both
aromatic and non-carboxyl aliphatic carbon in each sample. Spin counting experiments
demonstrate that less than 50% of the carbon in three of the fractions is observed in
the NMR experiment, and even after correction for different relaxation, the amounts
of aromatic and non-carboxyl aliphatic carbon determined by
13 C CP-MAS NMR are
dissimilar to those obtained by calculations. Unambiguous evidence is presented for
the predominance of aliphatic carboxyl groups in one of the fulvic acid fractions.
2.8.2 Mestranol
Okuno and Higgins et al [278] have described a procedure for determining residual levels of mestranol (an animal damage control chemosterilant) and its 2-hydroxy
homologue ethynyloestradiol in soil samples. The lower limit of detection was 0.1 ppm.
After extraction in acidic medium, the samples are cleaned up by Florisil column chromatography. Soil samples are further cleaned up on a gel permeation chromatographic
the industrial accident at Sevesco, Italy. Detection thresholds of 2–50 ppt were achieved
for agricultural soil samples.
2.8 MISCELLANEOUS ORGANIC COMPOUNDS
2.8.1 Humic and fulvic acids
Weber and Wilson et al [274] used anion and cation exchange resins to isolate fulvic
and humic acids from soil and water.
Ion-selective electrodes have been used to determine the stability constants for the
complexation of copper II ions with soil fulvic acids [275]. Two cases of binding sites
were found with conditional stability constants of about 1 × 10
6 and 8 × 10
3 .
Saar and Weber et al [276] compared methods based on spectrofluorimetry and
ion-selective electrode potentiometry for determining the complexes formed between
fulvic acid and heavy metal ions. The fluorescence properties of two fulvic acids, one
derived from the soil and the other from river water, were studied. The maximum
emission intensity occurred at 445–450 nm upon excitation at 350 nm, and the intensity varied with pH, reaching a maximum at pH 5.0 and decreasing rapidly as the pH
dropped below 4. Neither oxygen nor electrolyte concentration affected the fluorescence of the fulvic acid derived from the soil. Complexes of fulvic acid with copper,
lead, cobalt, nickel and manganese were examined and it was found that bound copper II ions quench fulvic acid fluorescence. Ion-selective electrode potentiometry was
used to demonstrate the close relationship between fluorescence quenching and fulvic
acid complexation of cupric ions. It is suggested that fluorescence and ion-selective
electrode analysis may not be measuring the same complexation phenomenon in the
cases of nickel and cobalt complexes with fulvic acid.
Wilson et al [277] carried out a compositional and solid-state nuclear magnetic
resonance (NMR) spectroscopic study of humic and fulvic acid and fractions present
in soil organic matter. The
13 C NMR study utilised cross polarisation-magic angle
spinning (CP-MAS) with spin counting. The elemental and functional group analyses
provided input for a series of analytical constraints calculations that yield an absolute
upper limit for the amount of aromatic carbon, and most probable estimates for both
aromatic and non-carboxyl aliphatic carbon in each sample. Spin counting experiments
demonstrate that less than 50% of the carbon in three of the fractions is observed in
the NMR experiment, and even after correction for different relaxation, the amounts
of aromatic and non-carboxyl aliphatic carbon determined by
13 C CP-MAS NMR are
dissimilar to those obtained by calculations. Unambiguous evidence is presented for
the predominance of aliphatic carboxyl groups in one of the fulvic acid fractions.
2.8.2 Mestranol
Okuno and Higgins et al [278] have described a procedure for determining residual levels of mestranol (an animal damage control chemosterilant) and its 2-hydroxy
homologue ethynyloestradiol in soil samples. The lower limit of detection was 0.1 ppm.
After extraction in acidic medium, the samples are cleaned up by Florisil column chromatography. Soil samples are further cleaned up on a gel permeation chromatographic