薄层层析-光度法联用测定甲基对硫膦中o,o′-二甲基-对硝基苯基硫代膦酸酯

Determination of o,o′-Dimethyl-p-Nitrophenyl Thiophosphonate in Methyl Parathion by Photometry Hyphenated with Thin Layer Chromatography

摘要: 应用薄层色谱法(TLC)使对硫膦中的主成分,o,o′-二甲基-对硝基苯基硫代膦酸酯(DMNPTP),与以杂质共存的二硝基与邻硝基衍生物分离.TLC法中用硅胶(G254)作吸附剂,用石油醚与乙酸乙酯(8+2)的混合物作为展开溶剂,经TCL分离后,用刀片将样品(含DMNPTP)的色谱带括下,经蒸发除去有机溶剂,用硝酸-高氯酸加热消化并蒸发至干后,用硝酸溶解残渣.此时,溶液中原来以DMNPTP存在的化合物已转化为正磷酸盐,随即用磷钒钼杂多酸光度法测定其磷含量,测定波长为其吸收峰450 nm,由测定值换算为DMNPTP的含量.

Abstract: Thin layer chromatography (TLC) was used to separate the main component,o,o′-dimethyl-p-nitrophenyl thiophosphonate (DMNPTP),from the dinitro and o-nitro derivatives which are present as impurities in methyl parathion.Silica gel (G254) was used as the adsorbent and a mixture of petroleum ether and ethylacetate (8+2) was used as the spreading solvent.After separation by TLC,the chromatographic band of the sample which contains the DMNPTP,was taken down from the TLC plate with a razor blade.After removing the organic solvent,and evaporation with HClO4-HNO3 to dryness,the residue was taken up with HNO3 and the PO3-4 transformed from DMNPTP,was determined photometrically be the molybdivanado-phosphoric acid method,measuring its absorbance at the absorption maxima of 450 nm.