RESUMO
OBJECTIVES: To study the decomposition kinetics of omethoate in blood. METHODS: The acetonitrile precipitated protein was added into the blood, with the chromatographic column of a Waters BEH C18 column ï¼2.1 mm×50 mm, 1.7 µmï¼, the mobile phase of 5 mmol/L ammonium acetate aqueous solution-methanol, and the gradient elution with a flow rate of 0.3 mL/min and injection volume of 2 µL. With electrospray ionization ï¼ESIï¼ source and positive ion detection, qualitative and quantitative analyses were taken using multi-reaction monitoring mode. Omethoate standard was added into blank human blood to the mass concentrations of 0.78, 1.40, 2.30, 4.50, and 7.20 µg/mL, and each mass concentration was preserved at 3 temperatures of -20 â, 4 â, and 20 â, respectively. The content of omethoate was detected at different time points ï¼0, 1, 3, 4, 7, 11, 15, 24, 32, 40, 48, 64, 80, 96, and 120 dï¼. RESULTS: Different concentrations of omethoate all showed a descended trend in human blood under different temperature conditions. The decomposition in storage environment of -20 â, 4 â, and 20 â was fit to a one-compartment open model with a first-order kinetic process, which could be expressed as Ct=Coe-αt, with the calculated theoretical values of omethoate concentration close to the measured values. CONCLUSIONS: All concentrations of omethoate are decomposed in the blood, which vary a lot in different preservation conditions. It is suggested that blood samples should be frozen and detected timely in suspected omethoate poisoning cases.
