褪色分光光度法间接测定草甘膦

Indirect Spectrophotometric Determination of Glyphosate in Waste Water

在ｐＨ＝５．６的醋酸－醋酸钠缓冲溶液中，草甘膦与微量过量的溴反应，剩余的溴能使罗丹明Ｂ褪色，以此建立了一种分光光度法测定草甘膦的新方法。在最佳条件下，草甘膦浓度与吸光度呈良好的线性关系。当加入溴的浓度分别为１．４４×１０－５ｍｏｌ／Ｌ和２．７２×１０－５ｍｏｌ／Ｌ时，测定范围分别为０～０．５ ｍｇ／Ｌ和０．４～０．９ ｍｇ／Ｌ。干扰试验表明，Ｆｅ２＋、Ｆｅ３＋和三乙胺有严重干扰，但可被阳离子交换树脂和吸附树脂从试样溶液内分离掉。方法用于草甘膦生产废水中草甘膦的测定时，加标回收率为９４％～１０１％。

A new spectropliotometric method is proposed for the determination of glyphosate. The method is based on the reaction of glyphosate with excess bromine and the subsequent color fading of rhodamine B by the excess bromine in HAc-NaAc buffer solution at pH=5. 6. When the added bromine water is 1. 44×l0-5 mol/L and 2. 72×10-5 mol/L re- spectively, Beer's law is obeyed at least over the concentration ranges of 0-0. 5 mg/L and 0. 4-0. 9 mg/L glyphosate respectively. The interference experiment shows that Fe3+, Fe2+ and triethylamine interfere with the determination of glyphosate seriously, but they can be removed from sample solution by cation exchange resin and adsorptive resin. The optimum reaction conditions were established. The method is applied to the determination of glyphosate in waste water from production. The recovery of glyphosate is 94%-101%.