Water pesticide residues

Peryea, F.J. and Creger, T.L. (1994) Vertical distribution of lead and arsenic in soils contaminated with lead arsenate pesticide residues. Water, Air, and Soil Pollution, 78(3-4), 297-306. 

Environmental Pesticides residues Water and soil analysis... 

The documented occurrence of pesticides in surface water is indicative that mnoff is an important pathway for transport of pesticide away from the site of appHcation. An estimated 160 t of atra2ine, 71 t of sima2ine, 56 t of metolachlor, and 18 t of alachlor enter the Gulf of Mexico from the Mississippi River annually as the result of mnoff (47). Field appHcation of pesticides inevitably leads to pesticide contamination of surface mnoff water unless mnoff does not occur while pesticide residues remain on the surface of the soil. The amount of pesticides transported in a field in mnoff varies from site to site. It is controUed by the timing of mnoff events, pesticide formulation, physical—chemical properties of the pesticide, and properties of the soil surface (48). Under worst-case conditions, 10% or more of the appHed pesticide can leave the edge of the field where it was appHed. 

Only particular solvents are suitable for certain purposes. The choice depending, for instance, on their residual water content or their acid-base nature if Rf values are to be reproduced [1, 2]. Halogen-containing solvents may not be employed for the determination of chlorinated pesticides. Similar considerations apply to PAH analyses. Pro analyst grades are no longer adequate for these purposes. It is true that it would be possible to manufacture universally pure solvents that were adequate for all analytical purposes, but they would then be too expensive for the final user [3, 4]. 

On-line LC-GC has frequently been used as a clean-up technique for the analysis of trace levels of contaminants (pesticides, plasticizers, dyestuffs and toxic organic chemicals) in water and food products. Several different approaches have been proposed for the analysis of contaminants by on-line LC-GC. Since pesticide residues occur at low concentration in water, soil or food, extraction and concentration is needed before GC analysis is carried out. 

The Environmental Protection Agency (EPA) has prepared a manual of pesticide residue analysis dealing with samples of blood, urine, human tissue, and excreta, as well as water, air. soil, and dust. 

Despite the use of 2.5 million tons of pesticide worldwide, approximately 35% of potential crop production is lost to pests. An additional 20% is lost to pests that attack the food post-harvest. Thus, nearly one-half of all potential world food supply is lost to pests despite human efforts to prevent this loss. Pesticides, in addition to saving about 10% of world food supply, cause serious environmental and public health problems. These problems include human pesticide poisonings fish and bird kills destruction of beneficial natural enemies pesticide resistance contamination of food and water with pesticide residues and inadvertent destruction of some crops. 

Groundwater has also been surveyed for methyl parathion. In a study of well water in selected California communities, methyl parathion was not detected (detection limit of 5 ppb) in the 54 wells sampled (Maddy et al. 1982), even though the insecticide had been used in the areas studied for over 15 years. An analysis of 358 wells in Wisconsin produced the same negative results (Krill and Sonzogni 1986). In a sampling of California well water for pesticide residues, no methyl parathion was detected in any of the well water samples (California EPA 1995). In a study to determine the residue levels of pesticides in shallow groundwater of the United States, water samples from 1,012 wells and 22 springs were analyzed. Methyl parathion was not detected in any of the water samples (Kolpin et al. 1998). In a study of water from near-surface aquifers in the Midwest, methyl parathion was not detected in any of the water samples from 94 wells that were analyzed for pesticide levels (Kolpin et al. 1995). 

An extensive study was undertaken to determine if pesticide residues are present in any infant formula products (Gelardi and Mountford 1993). Milk- and soy-based formulas were analyzed, as was the water used to make the formula. No pesticide residues, including methyl parathion, were detected in any infant formula manufactured in the United States. Thus, it does not appear that infants will be exposed to... 

Ambrus A, Visi W, Zakar F, et al. 1981. General method for determination of pesticide residues in samples of plant origin, soil, and water. III. Gas chromatographic analysis and confirmation. J Assoc Off Anal Chem 64 749-768. 

Environment Canada. 1999. Environment Canada, Environmental Protection Branch, Atlantic Region. March 1999. Pesticide residue in sediment and water from two watersheds in Prince Edward Island,... 

JoshiHC. 1987. Pesticide residues in some fish ponds in West Bengal (India). Technical Annual-Indian Association for Water Pollution Control 14 35-38. 

A method for determining the LOD and LOQ for water samples was proposed by the US EPA. This method has also been discussed by Roy-Keith Smith in his book titled Handbook of Environmental Analysis .The method has also been proposed by the US EPA in their guidelines for Assigning Values to Non-detected/Non-quantitied Pesticide Residues in Human Health Pood Exposure Assessments . ... 

The principles of validation of residue methods for food, water and soil are generally the same. However, not all procedures and requirements are identical. From the public s point of view, the information on residues in food is probably the most important task. Compared with the other two areas (water and soil), the food sector is characterized by the largest number of regulations and legal limits. Therefore, this overview of validation requirements of enforcement methods will focus on methods for pesticide residues in food. 

Extraction of residues from soil samples is much more difficult than their extraction from plant or water samples. The pesticide residues in the soil exist often in several forms as bound residue , which may affect the extraction efficiency of pesticides from the soil. Then, various extraction methods such as organic solvent extraction, Soxhlet extraction, sonication extraction, microwave dissolution and supercritical fluid extraction (SEE) are used. Some extraction methods are described in the following. 

An SPE method has been developed to replace the classical LLP method. Water sample is extracted with an SPE column such as Cig and styrene-divinylbenzene copolymer (PS-2) cartridges, which consist of a reversed bonded-phase silica sorbent, provided as an extraction tool. This is a simple and rapid method, and applied to the determination of residual amounts of naproanilide, propanil, mefenacet, etc. This system determines the residual amounts of most of the pesticides and has been successfully applied to determination of pesticides in water. 

A monitoring system has been established to determine 90 pesticides including anilides and 10 related degradation products in river water. Pesticide residues in the water sample are collected on a PS-2 cartridge (265-mg) at a flow rate of 10 mL min, eluted with 3 mL of acetone, 3 mL of n-hexane and 3 mL of ethyl acetate successively, and determined by GC/MS. Overall recoveries ranged from 72 to 118%. Recoveries of mepronil, naproanilide, propanil and flutolanil at fortification levels of 0.1 and 2 mg kg Mn water by this method were 80-112%. The LODs were 0.01 -0.1 pg L ... 

Thus, organic solvent extraction methods for the extraction of pesticides from water samples can be replaced by the SPE method using Ci8 and PS-2. Ethobenzanid, clomeprop, naproanilide and their acidic metabolites are determined by a multi-residue analytical method using Cig or PS-2 cartridge extraction after acidification of the water samples with hydrochloric acid or other acidic media, followed by HPLC or LC/MS detection. 

Acetone, n-hexane, acetonitrile, ethyl acetate, pesticide residue analysis grade Aluminum oxide, Aluminumoxid 90, activity 11-111, 70-230 mesh MSTM (Merck) Anhydrous sodium sulfate, sodium chloride, special grade Distilled water, HPLC grade... 

Distilled water, high-performance liquid chromatography grade Acetone, ethyl acetate, diethyl ether, acetonitrile, n-hexane, benzene, pesticide residue analysis grade... 

Accurate, precise and sensitive analytical methods are important to the collection of data needed for regulatory decisions about pesticide registration. This article describes the various components of analytical method development, validation and implementation that affect the collection of pesticide residue distribution data for regulatory assessment of environmental fate and water quality impacts. Included in this discussion are both the technical needs of analytical methods and the attributes of study design and sample collection needed to develop data that are useful for regulatory purposes. 

The ECL evaluates analytical methods for detecting pesticide residues in the environment to ensure that the methods are suitable for monitoring pesticide residues in soil and water. State, tribal and federal laboratories may access an Index of Environmental Chemistry Methods for a list of available methods. The ECL also provides the State pesticide laboratories with technical and QA support and training in pesticide analytical chemistry. 

The emphasis that the FQPA placed on the assessment of pesticide residues in drinking water, for example, led to the collection and analysis of data on the effects of drinking water treatment processes on pesticide residues. These data were presented to the FIFRA Science Advisory Board to highlight the variability in the effects of treatment on different kinds of pesticides and the products formed and the variability of treatment processes employed at different locations and at different collection time intervals at an individual location. These complexities led to the current proposal... 

For pesticide residue immunoassays, matrices may include surface or groundwater, soil, sediment and plant or animal tissue or fluids. Aqueous samples may not require preparation prior to analysis, other than concentration. For other matrices, extractions or other cleanup steps are needed and these steps require the integration of the extracting solvent with the immunoassay. When solvent extraction is required, solvent effects on the assay are determined during assay optimization. Another option is to extract in the desired solvent, then conduct a solvent exchange into a more miscible solvent. Immunoassays perform best with water-miscible solvents when solvent concentrations are below 20%. Our experience has been that nearly every matrix requires a complete validation. Various soil types and even urine samples from different animals within a species may cause enough variation that validation in only a few samples is not sufficient. 

SFE of fruits and vegetables and meat products has been reported, but the sample preparation techniques necessary to obtain reproducible results are extremely time consuming. Solid absorbents such as Hydromatrix, Extrelut " anhydrous magnesium sulfate or absorbent polymers are required to control the level of water in the sample for the extraction of the nonpolar pesticides. Without the addition of Hydromatrix, nonpolar pesticides cannot penetrate the water barrier between the sample particles and the supercritical CO2. The sample is normally frozen and the addition of dry-ice may be required to reduce losses due to degradation and/or evaporation. Thorough reviews of the advantages and limitations of SFE in pesticide residues... 

Biosensors may provide the basis for in-field analyses and real-time process analysis. However, biosensors are generally limited to the determination of a limited range of analytes in defined matrices. Enzyme-based biosensors, principally acetylcholinesterase (AChE) inhibition, have been successfully used in environmental analysis for residues of dichlorvos and paraoxon, " carbaryl " and carbofuran. " Immunochemically based biosensors may be the basis for the determination of pesticide residues in liquid samples, principally water and environmental samples, but also fruit juices. The sensors can be linked to transducers, for example based on a piezo-... 

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