Influence of dissolved humic acid and Ca-montmorillinite clay on pesticide extraction efficiency from water using solid-phase extraction disks

Article Abstract:

Gas chromatography/mass spectrometry of water samples containing all possible combinations of pesticide, Ca-montmorillinite clay and commercial humic acid at different amounts showed varying reactions to pH and had different extraction efficiencies. Samples with a high concentration of Ca-montmorillinite and at pH 8 had a low recovery of pesticides because of increased surface area and subsequent adsorption. Samples with a high concentration of humic acid had a stronger effect on extraction efficiency when water was at pH 6 than at higher pH levels.

Management, Environmental aspects, Biodegradation, Organic water pollutants, Organic water pollution

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Trace level pesticide detections in Arkansas surface waters

Article Abstract:

Lawrence County, MS and Phillips and Jefferson counties in Arkansas conducted a three-year pesticide survey of surface water in an effort to assess nonpoint source water pollution. The survey, which ran from 1989 to 1991, sampled about 59-62 lake and river/stream sites eight times and monitored pesticides widely used in Arkansas. It was found out that 5% of 256 total detections were above safe levels. The pesticide cyanazine had the highest incidence of repeated detections during the eight sampling periods.

Research and Development in the Physical, Engineering, and Life Sciences, Waste Management and Remediation Services, Pesticide and Other Agricultural Chemical Manufacturing, Pesticides & Other Ag Chemicals, Water Pollution, Agricultural chemicals, not elsewhere classified, Water Pollution Control R&D, Evaluation, Arkansas, Surveys, Water pollution research

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Stability of various pesticides on membranous solid-phase extraction media

Article Abstract:

The resulting improvement in pesticide stability due to pesticide protection from hydrolysis and microbial decomposition during its absorption to solid- phase extraction (SPE) disks is discussed. The relative storage stability of selected pesticides on SPE disks was compared to the stability of pesticides in water. The preservation and enhancement of the stability of these peptides was demonstrated.

Research, Methods, Extraction (Chemistry)

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