Dimethoate detection limit

In situ quantitation The absorption photometric quantitation was carried out in M flectance at a mean wavelength of A, = 370 nm. The detection limits per chromatogran zone lay between 10 ng for dimethoate and 20 ng for parathion-ethyl. 

Table 23.5 shows recoveries of organophosphorus compounds using C18 octadecyl silica and different polymeric sorbent disks. Recoveries of 53 to 164% onC18 except for dimethoate (0%) and 64 to 99% on polymers have been reported. Some metabolites have been determined with recoveries of 97 to 100%. " The chromatographic methods used in combination with SPE were LC-UV/DAD GC-NPD, and GC-MS. Detection limits using SPE with disks range from 0.02 to 4.3 /rg/1 depending of the sample volumes used for the extraction and of the analytical methods. 

Water samples (800 ml) were filtered through the membranes and were extracted by methanol after addition of sodium sulphate. Dimethoate, parathion, and parathion-methyl were tested. The method enabled the determination of these compormds with a detection limit of 0.05 /rg/1 and recoveries ranging from 66 to 94%. 

ECL in combination with some techniques has also been used to determine pesticides [112], herbicides [113], and alkaloids. Pesticides [114], acephate and dimethoate, were determined using a composite electrode (a TBR-multi-walled carbon nanotube paste electrode) with coreagent TPA [115]. Other literature revealed a rapid method for the determination of galanthamine (in Bulbus lycoridis radiatae) [116]. For sensitive determination of verticine and verticinone in Bulbus fritillariae, CE/Ru(bpy)3 ECL system with the assistance of ionic liquids was successfully established. Detection limits of 1.25 x 10 ° mol L for verticine and 1 x 10 ° mol L for verticinone were obtained (S/N = 3). Developed method was successfully applied to determine the amounts of alkaloids in Bulbus fritillariae [117]. 

The phosphorus content offers a sensitive detection mode for fensulfothion, metasystox, disul-foton, methylparathion, folithion, hinosan, malathion, dimethoate, formothion, phosphamidon, phosalone, thiometon, and quinalphos. After development, the plates were heated at 110 C for 2 h, yielding inorganic phosphates. These reacted with anunonium molybdate to give phosphomolybdate. The reduction with ascorbic acid leads to a blue complex with a detection limit of 0.1-0.2 ftg (160). 

The first field test was successful. Both dimethoate and malathion declined exponentially (Figure 9) and exhibited efficiency factors comparable to the efficiency factors found in the pilot tests. An efficiency factor could be calculated for baygon, but not for diazinon. Some sediment was present into the bottom of the holding tank which could have been slowly releasing baygon and diazinon in the bulk liquid. Nevertheless, after 24 hours of treatment, all pesticides were below the limit of detection. 

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