Pesticides recoveries

The effects of water temperature and pesticide concentration on pesticide recoveries were tested by Moye et al The pesticides included alachlor, atrazine, bromacil, chlorothalonil, chloropyrifos, diazinon, endosulfan, simazine and trifluralin. Temperatures of 5,25,45 and 65 °C were tested and concentrations of 0.1,1.0 and 10 pgL were used. Water temperature had a pronounced effect on the recoveries whereas the concentration did not seem to have as great an effect. 

TABLE 7.1 PERCENT PESTICIDE RECOVERY WITH VARIOUS CLEANUP METHODS 1 (9)... 

Hjrpothesis-testing statistics are used to compare the properties of samples either with other samples or with some theory about them. For instance, you may be interested in whether two samples can be regarded as having different means, whether the concentration of a pesticide in a soil sample can be regarded as randomly distributed, or whether soil organic matter is linearly related to pesticide recovery. 

By this method, the pesticide recoveries in samples spiked with 0.10 mg/L of each compound were greater than 70% for 123 active ingredients (out of 153 pesticides added) in red wines, and for 128 active ingredients in white wines, respectively. Recoveries of 52 and 62 compounds higher than 90% were observed for extracted red and white wines, respectively. Thirty pesticides in red wines, and 25 pesticides in white wines, showed recoveries below 70%. These results are similar to those observed for the red and white wines spiked at low concentration (0.01 mg/L each) recoveries above 70% were found in 116 and 124 pesticide residues from extracted red and white wines, respectively. 

For the ecological risk assessment of pesticides, recovery of affected aquatic populations is an important aspect. Due to spatial and temporal constraints, recovery cannot be studied experimentally for all species. For instance, species that lack a resistant life stage and also lack aerial dispersal cannot recover after becoming extinct in microcosms or mesocosms. It is therefore proposed to estimate recovery using ecological modeling. 

Table 13-2. Pesticide recoveries from selected foods using large-scale supercritical fluid extraction with CO,...

Another class of adsorbents, graphitized carbon blacks (GCB), exhibit the same positive characteristics as the bonded silicas, with the difference of being more retentive, absolutely nonpolar and nonporous. With GCBs, quite good results have been obtained for classic chlorinated pesticides. Recoveries of selected OCPs from different adsorbents are reported in Table 22.4. 

Figure 2.46 Pesticide recoveries versus fat content (Lehotay, 2013).

Sample Cleanup. The recoveries from a quick cleanup method for waste solvents based on sample filtration through a Elorisd and sodium sulfate column are given in Table 2 (40). This method offers an alternative for analysts who need to confirm the presence or absence of pesticides or PCBs. 

A multiresidue analytical method based on sohd-phase extraction enrichment combined with ce has been reported to isolate, recover, and quantitate three sulfonylurea herbicides (chlorsulfuron, chlorimuron, and metasulfuron) from soil samples (105). Optimi2ation for ce separation was achieved using an overlapping resolution map scheme. The recovery of each herbicide was >80% and the limit of detection was 10 ppb (see Soil chemistry of pesticides). 

Other Applications. Among other industrial uses of lime are causticizing agent in kraft (sulfate) paper (qv) plants recovery of ammonia (qv) from NH4CI (Solvay process) recovery of magnesium (qv) from seawater and brines via precipitation of Mg(OH)2 production of pesticides such as... 

Although eggshell thinning attributable to DDE exposure has occurred in birds in the UK, the lethal and siiblethal effects of the cyclodiene pesticides aldrin, dieldrin and heptachlor are also believed to have contributed to the population effects, particularly in the case of the sparrowhawk and peregrine falcon. Following the withdrawal of DDT and the cyclodienes from use in the UK, Europe and North America, bird of prey populations that were severely affected have shown partial or complete recovery. ... 

HCN is now also used to make (C1CN)3 for pesticides (9%), NaCN for gold recovery (13%), and chelating agents such as edta (4%), etc. 

FIGURE 5.7 Peregrine population size in Britain (1930-1939 = 100) showing the 1961 population decline and subsequent recovery, together with an outline of pesticide usage (from Ratcliffe 1993). 

Fleming, W.J. and Grue, C.E. (1981). Recovery of cholinesterase activity in 5 avian species exposed to dicrotophos, an organo-phosphorus pesticide. Pesticide Biochemistry and Physiology 16,129-135. 

Newton, I. and Wyllie, I. (1992). Recovery of a sparrowhawk population in relation to declining pesticide contamination. Journal of Applied Ecology 29, 476 84. 

Method Pesticide Matrix ELOQ (mgkg ) LLMV (mg kg ) Av. recovery standard deviation Calc. MDL (mg kg ) Calc. MQL (mg kg ) Ref. 

To demonstrate the validity of an analytical method, data regarding working range/ calibration, recovery, repeatability, specificity and LOQ have to be provided for each relevant sample matrix. Most often these data have to be collected from several studies, e.g., from several validation reports of the developer of the method, the independent laboratory validation or the confirmatory method trials. If the intended use of a pesticide is not restricted to one matrix type and if residues are transferred via feedstuffs to animals and finally to foodstuffs of animal origin, up to 30 sets of the quality parameters described above are necessary for each analyte of the residue definition. Table 2 can be used as a checklist to monitor the completeness of required data. 

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