磷钼蓝分光光度法测定有机磷农药残留量的改进

对有机磷农药残留量的磷钼蓝分光光度测定法进行了改进。探讨了检测波长、显色反应条件、共存离子等因素对测定结果的影响,并与国标GB/T 6913-2008比较灵敏度、准确度、精密度、稳定性。研究表明:当检测波长为890 nm;反应体系为2.0 mL钼酸铵溶液(26 g/L)、1.0 mL抗坏血酸溶液(100 g/L)并添加0.4 g/L ED-TA;45℃水浴条件下显色10 min。在此条件下,测定吸光度与质量呈线性关系,PO43-的量在0～160μg内符合比耳定律,磷酸盐测定回归方程为Y=0.004 53X-0.002 29,相关系数(R2)=0.999 84,表观摩尔吸光系数为2.118×104 L/(mol.cm),方法回收率为95.199%～102.097%。此方法操作简单,可满足有机磷农药残留量的检测要求。

Improvement of Spectrophotometric Determination of Organic Phosphorus Pesticide by Phospho-Molybdenum Blue

The improvement of spectrophotometric determination of organic phosphorus pesticide by phospho-molybdenum blue was studied.The effects of wave-length,chromogenic reaction and coexisting ions were investigated.The sensitivity,accuracy,precision and stability of the improved method were compared with GB/T 6913-2008.A good linear relationship between absorbance(A) and phosphate mass(μg) was observed under the condition of : wavelength 890 nm,2.00 mL ammonium molybdate solution(26 g/L),1.00 mL ascorbic acid(100g/L,containing 0.4 g /L EDTA),and incubated at 45℃ for 10min,.The equation was expressed as Y=0.004 53X-0.002 29(R2=0.999 84),and the apparent molar absorption was 2.118×104 L/(mol·cm).The mass concentration of PO3-4 is 0~160 μg and fits to Beer's law.Mean recoveries of phosphate varied from 95.199% to 102.097%.The method is easy to operate and applicable to the requirements of organophosphorus pesticide residues detection.