Chapter 4
Organometallic compounds in soils
4.1 ORGANOARSENIC COMPOUNDS
Gas chromatography
Ordanake et al [1] have reported the application of gas chromatography with multiple
ion detection followed hydride generation with sodium borohydride to the determination of mono and dimethyl arsenic compounds, trimethyl arsenic oxide and inorganic
arsenic in soil and sediments. Recoveries in spiking experiments were 100–102%
(mono and dimethyl arsenic compounds and inorganic arsenic) and 72% (trimethyl
arsenic oxide).
Soderquist et al [2] determined hydroxydimethyl arsine oxide in soil by converting
it to iododimethylarsine using hydrogen iodide followed determination at 105
◦ C on
a column (450 cm × 2.8 mm) packed with 10% DC-200 on Gas-Chrom Q (60–80
mesh) with nitrogen as carrier gas (20–30 min
−1 ) and electron capture detection. The
recovery of hydroxydimethylane oxide (0.15 ppm) added to soil was 91.3 ± 5.1%.
Miscellaneous
Because of the wide usage of organic arsenical, and because little information exists
on the fate of these compounds in soils, Von Endt et al [3] used monosodium methane
arsenic acid (MSMA) as a model for studying the metabolism of this class of compounds
by soil micro-organisms.
Experiments involving the release of radioactive carbon dioxide from monosodium
methane arsenic acid −14
◦ C treated soils were conducted in a system consisting of two
test tubes connected in series. One tube contained 5 g of treated soil (at 10 and 100 ppm
of monosodium methane arsenic acid) while a second tube contained a trapping mixture, 2-methoxythanol and monoethanolamine (7–10, v/v. carbon dioxide-free air
was passed over the soil and metabolic
14 CO 2 was collected in the trapping solution.
Preliminary studies indicated that the decomposition of monosodium methane
arsenic acid to carbon dioxide was a slow process that did not involve a lag phase.
Hagerstown silty clay loam slowly evolved
14 CO 2 from MSMA14 C applied at a rate of
100ppm. Only 7% decomposition was observed after 60 days. In another experiment
involving four soils and two rates of monosodium methane arsenic acid application,
the rate of decomposition was again a slow process (Fig. 4.1). After three weeks’ incubation, all soils had evolved radioactive carbon dioxide to a degree proportional to the
Organometallic compounds in soils
4.1 ORGANOARSENIC COMPOUNDS
Gas chromatography
Ordanake et al [1] have reported the application of gas chromatography with multiple
ion detection followed hydride generation with sodium borohydride to the determination of mono and dimethyl arsenic compounds, trimethyl arsenic oxide and inorganic
arsenic in soil and sediments. Recoveries in spiking experiments were 100–102%
(mono and dimethyl arsenic compounds and inorganic arsenic) and 72% (trimethyl
arsenic oxide).
Soderquist et al [2] determined hydroxydimethyl arsine oxide in soil by converting
it to iododimethylarsine using hydrogen iodide followed determination at 105
◦ C on
a column (450 cm × 2.8 mm) packed with 10% DC-200 on Gas-Chrom Q (60–80
mesh) with nitrogen as carrier gas (20–30 min
−1 ) and electron capture detection. The
recovery of hydroxydimethylane oxide (0.15 ppm) added to soil was 91.3 ± 5.1%.
Miscellaneous
Because of the wide usage of organic arsenical, and because little information exists
on the fate of these compounds in soils, Von Endt et al [3] used monosodium methane
arsenic acid (MSMA) as a model for studying the metabolism of this class of compounds
by soil micro-organisms.
Experiments involving the release of radioactive carbon dioxide from monosodium
methane arsenic acid −14
◦ C treated soils were conducted in a system consisting of two
test tubes connected in series. One tube contained 5 g of treated soil (at 10 and 100 ppm
of monosodium methane arsenic acid) while a second tube contained a trapping mixture, 2-methoxythanol and monoethanolamine (7–10, v/v. carbon dioxide-free air
was passed over the soil and metabolic
14 CO 2 was collected in the trapping solution.
Preliminary studies indicated that the decomposition of monosodium methane
arsenic acid to carbon dioxide was a slow process that did not involve a lag phase.
Hagerstown silty clay loam slowly evolved
14 CO 2 from MSMA14 C applied at a rate of
100ppm. Only 7% decomposition was observed after 60 days. In another experiment
involving four soils and two rates of monosodium methane arsenic acid application,
the rate of decomposition was again a slow process (Fig. 4.1). After three weeks’ incubation, all soils had evolved radioactive carbon dioxide to a degree proportional to the