| Due to its high sensitivity, wide linear range and easy implementation, chemiluminescence（CL） has been widely applied in pharmaceutical analysis, food safety, environmental science and life science and so on. In this paper, a new chemiluminescence method for the determination of organophosphorous pesticides was proposed based on the chemiluminescence phenomenon of luminol-hydrogen peroxide in alkaline medium, selecting six structurally similar organophosphorus pesticide fenthion, phoxim, chlorpyrifos, fenitrothion, dichlorvos and phosphamidon as a typical representative. Meanwhile the possible mechanism of chemiluminescence reaction was explored and putted forward. And the sensitizing mechanism of sensitizer was also discussed. The principal findings went as follows:1ã€A novel chemiluminescence method for the determination of fenthion based on the reaction of luminol and H2O2 in the presence of NaBr has been established. Under the optimal conditions, the CL intensity is linear to the fenthion concentration in the range of 1.0×10-8 g/mL～1.0×10-6g/mL, and the detection limit is 2.5×10-9 g/mL. The relative standard is less than 1.7 % for 5.0×10-7 g/mL fenthion（n=11）. This method has been successfully applied to the determination of fenthion in fruits and vegetable samples.2ã€A novel chemiluminescence method for the determination of phoxim, chlorpyrifos and fenitrothion based on the reaction of luminol and H2O2 in the presence of NaCl has been established. The calibration graph is linear for 1.0×10-8g/mL～1.0×10-6 g/mL, the detection limit are separately 5.4×10-9g/mL, 3.5×10-9 g/mL and 4×10-9 g/mL. The relative standard RSD are separately 4.6 %, 3.9 % and 1.2 % for 5.0×l0-7 g/mL phoxim, chlorpyrifos and fenitrothion （n=11）. This method has been successfully applied to the determination of phoximã€chlorpyrifos and fenitrothion residue in vegetable samples and the results were compared to GC method.3ã€A method with chemiluminescence detection was developed for dichlorvos in the vegetable samples, based on the reaction of dichlorvos with luminol- hydrogen peroxide in alkaline medium with CTMAB being enhancer. The calibration graph is linear for 5.0×10-8g/mL～1.0×10-6g/mL, the detection limit are 6.0×10-8g/mL. The relative standard RSD is 1.49 % for 5.0×10-7g/mL dichlorvos （n=11）. The method was applied to the determination of dichlorvos in vegetable samples, the recovery was between 115%-124%. 4ã€A novel chemiluminescence method has been developed for the determination of phosphamidon in environmental water sample, based on the reaction of phosphamidon with luminol-H2O2 in alkaline medium with sodium dodecyl benzene sulplhate （SDBS） being enhancer. Under the optimum conditions, the increased CL intensity was proportional with the concentration of phosphamidon in the range of 1.0×10-8 g/mL～1.0×10-6g/mL and the detection limit was 3.8×10-9 g/mL. The relative standard was 2 % for 5.0×10-7 g/mL phosphamidon （n=11）. The proposed method was applied to the determination of phosphamidon residue in vegetable samples with satisfactory results.5ã€Based on the kinetic curve, fluorescence spectrum, UV spectrum and combining with the experiment phenomenon of chemiluminescence reaction, the possible CL mechanism of organophoaphorous pesticides fenthion（phoxim, chlorpyrifos, fenitrothion, dichlorvos, phosphamidon） with luminol-H2O2 was proposed. Meanwhile , the chemiluminescence intensity could be greatly enhanced by adding surfactants（sodium dodecyl benzene sulplhate, ceryltrimethylammonium bromide）and salts（NaBr, NaCl） to the system of organophoaphorous pesticides-luminol-H2O2. The sensitizing mechanism of surfactants was explored by five ways of solubilization, stability, electrostatic effects, increased sensitivity and altering the pH of the microenvironment. And the hypothesis of "induced effect" was proposed for the sensitizing mechanism of salts. |
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