Humic content

In the above-mentioned method by Hodgeson el acifluorfen was determined by GC/ECD after the extraction with a 47-mm PS-DVB disk and derivatization with diazomethane. The conditions for GC/ECD were as follows column, DB-5 fused silica (30 m X 0.32-mm i.d., 0.25-p.m film thickness) He carrier gas velocity, 25 cm s (210°C), detector makeup gas, methane-argon (5 95), 30mLmin column temperature, 50 °C (5 min), 10°Cmin to 210 °C (5 min) and to 230 °C (10 min) injection port and detector temperature, 220 and 300 °C, respectively injection method, splitless mode. The recovery of acifluorfen from purified water, dechlorinated tap water and high humic content surface water fortified at 0.5-2.0 ug was 59-150% and the LOD was 25 ngL Acifluorfen after derivatization with various chlorofor-mates was also determined by GC/MS using an SE-54 column (25 m x 0.20-mm i.d., 0.32- um Aim thickness), and the average recovery of acifluorfen fortified between 0.05 and 0.2 ugL was 78%. ... 

High humic content in soil may require pretreatment. 

Tranvik, L. J. 1988a. Availability of dissolved organic carbon for planktonic bacteria in oligotrophic lakes of differing humic content. Microbial Ecology 16 311-322. 

Rasmussen, J. B., L Godbout, and M. Schallenberg. 1989. The humic content of lake water and its relationship to watershed and lake morphometry. Limnology and Oceanography 34 1336-1343. 

Graneli, W., M. Lindell, and L. Tranvik. 1996. Photooxidative production of dissolved inorganic carbon in lakes of different humic content. Limnology and Oceanography 41 698-706. 

The humic content of soils varies from 0 to almost 10%. In surface waters, the humic content, expressed as dissolved organic carbon (DOC), varies from 0.1 to 50 ppm in dark-water swamps. In ocean waters, the DOC varies from 0.5 to 1.2 ppm at the surface, and the DOC in samples from deep groundwaters varies from 0.1 to 10 ppm (7). In addition, about 10% of the DOC in surface waters is found in suspended matter, either as organic or organically coated inorganic particulates. 

The potential usefulness of any analytical procedure should be assessed by carrying out control experiments in samples comparable to those collected for the field studies. Analytes in environmental samples are often determined at the ppm-ppb levels. While an immunoassay may appear to be specific, sensitive and reliable under the pristine conditions of the laboratory (e.g. when the test substance is in buffer), it may give false results with environmental samples that vary sufficiently (e.g. in pH, ionic strength, viscosity, solubility, humic content, etc.) to alter the antigen-antibody interaction or interfere with the monitoring systems. Samples collected at the point source where the analyte is most concentrated (e.g. at the... 

J. J. Lindell, W. Graneli, L. J. Tranvik (1996). Effects of sunlight on bacterial growth in lakes of different humic content. Aquat. Microb. Ecol., 11,138-141. 

In subsurface oxic soil near Los Alamos National Laboratory, USA, plutonium is relatively mobile and has been transported primarily by colloids in the 25-450 pm size range. Moreover, the association with these colloids is strong and removal of Pu from them is very slow. By contrast, near Sellafield in wet anoxic soil, most of the Pu is quickly immobilized in the sediments although a small fraction remain mobile. Differences in oxidation state (Pu(V) vs. Pu(lV)) as well as in humic content of the soils may explain these differences in mobility. 

The natural organic (humic) content of the soil largely remains after these processes and can be used for successful cultivation. Hydrocarbons are re-precipitated as the water cools, whereas some compounds, such as pesticides, are degraded to less-toxic materials during the extraction process. Soil containing explosives has also been treated in the same pilot plant using static extraction [48]. The destruction of TNT, RDX and HMX was 99.99%, 99.9% and 97.9%, respectively. 

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