Insecticides, detection

A.L. Jenkins, R. Yin, and J.L. Jensen, Molecularly imprinted polymer sensors for pesticide and insecticide detection in water. Analyst 126, 798-802 (2001). 

H. Schulze, S.B. Muench, F. Villatte, R.D. Schmid and T.T. Bachmann, Insecticide detection through protein engineering of Nippostrongylus brasiliensis acetylcholinesterase B, Anal. Chem., 77 (2005) 5823-5830. 

Of the 44 pesticides and three degradates analyzed for in surface waters of the Lake Erie Basin, 30 were detected at least once [75]. Atrazine was detected in every water sample, including samples from an area with less than 10% row crops (e.g., corn). The atrazine degradate deethylatrazine and the herbicide metolachlor were detected in 99% of the samples (Fig. 11). Eight of the 47 pesticides and degradates were detected in at least 50% of the water samples. All eight of these are herbicides used on row crops, except for prometon, which is used primarily in urban areas. Diazinon and chlorpyrifos were the most frequently detected insecticides, detected in 43% and 22% of the water samples, respectively. The most heavily applied agricultural pesticide not de-... 

These methods are employed for the detection and determination of antibiotics and substances with similar effects, like alkaloids, insecticides, fungicides, mycotoxins, vitamins, bitter principles and saponins [14]. 

Manual transfer of the chromatographically separated substance to the detector . These include, for example, the detection of antibiotically active substances, plant and animal hormones, mycotoxins, insecticides, spice and bitter principles and alkaloids. The frequency distribution of their employment is shown in Figure 54 [295]. 

The detection limits for thiophosphoric acid insecticides are 100 ng and for benzodiazepines 20 ng substance per chromatogram zone. 

The detection limits for peroxides are about 500 ng or with N,N,N, N -tetramethyl-p-phenylenediamine reagent 50 ng substance per chromatogram zone [4]. The detection limits for insecticides are 5 pg per chromatogram zone in the most unfavorable cases [7]. 

Note It is occasionally recommended that sodium acetate be added to the reagent [2]. Thiophosphate insecticides with a simple P—S bond yield yellow chromatogram zones and those with a P=S double bond yield brown ones on a light brown background [10]. Further treatment of the stained chromatogram with iodine vapors increases the detection sensitivity [7] more than does spraying afterwards with caustic soda solution, which is also occasionally recommended [16, 17, 20, 21]. 

Methyl parathion has been released to the environment mainly as a result of its use as an insecticide on crops. It is applied to agricultural crops by aerial or ground spraying equipment. Methyl parathion has been detected in surface waters and sediments, rainwater, aquatic organisms, and food. There are no known natural sources of the compound. Methyl parathion has been identified in at least 16 of the 1,585 hazardous waste sites on the NPL (HazDat 2001). 

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). 

Citrus fruits from markets in Spain were analyzed for residues of methyl parathion along with other organophosphorus insecticides (Torres et al. 1997). Of the 171 orange samples analyzed, 14 had levels of methyl parathion <0.2 ppm, while 5 had levels >0.2 ppm. Levels ranged from the 0.1 ppm limit of detection to 3.8 ppm depending on the type of orange. Of the 15 grapefruit samples analyzed, 1 was found to contain methyl parathion at a level of 0.3 ppm. 

Ackermann H. 1966. [Enzymatic detection of organophosphorus insecticides using thin layer chromatography]. Nahrung 10 273-274. (German)... 

Phosphorescence quenching la 35 -, detection limits la 15 -, time dependance la 34 Phosphoric acid la 179,185,242,278,430 Phosphoric acid esters la 44,170 Phosphoric acid insecticides lb 115,332, 339,340... 

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