流动注射-化学发光法测定百草枯的含量

Determination of Paraquat by Flow Injection-Chemiluminescence

基于百草枯在碱性环境中能够增强铁氰化钾-鲁米诺体系的化学发光强度,提出了流动注射-化学发光法测定百草枯含量的方法,并对该体系的发光机理进行了探讨。1.0×10-3mol·L^(-1)铁氰化钾标准溶液与百草枯溶液通过三通管混合,经10 cm长的混合管进入流通池,然后将含0.005 mol·L^(-1)氢氧化钠的2.0×10^(-6)mol·L^(-1)鲁米诺标准溶液载入上述混合溶液中,记录信号值。试验推测在碱性条件下,铁氰化钾催化溶解氧氧化鲁米诺产生化学发光,百草枯的加入使得鲁米诺氧化产物3-氨基邻苯二甲酸根离子的激发态浓度水平增大,从而发出更强的光。在最佳试验条件下,百草枯的质量浓度分别在5.0×10^(-4)~1.0×10^(-2)g·L^(-1)和2.0×10^(-2)~1.0×10^(-1)g·L^(-1)内与其对应的化学发光强度呈线性关系,检出限为7.4×10-5g·L^(-1);对百草枯标准溶液平行测定11次,测定值的相对标准偏差不超过5.0%;对空白尿样进行加标回收试验,百草枯的回收率为96.4%~104%。

Based on the fact that paraquat could enhance the chemiluminescence intensity of potassium ferricyanate-luminol system in alkaline environment, a method for the determination of paraquat by flow injection-chemiluminescence was proposed, and the luminescence mechanism of the system was discussed. 1.0×10-3mol·L^(-1)potassium ferricyanate standard solution was mixed with paraquat solution through a three-way tube and the mixture was entered into the circulation tank through a 10 cm-mixing tube. Then 2.0×10^(-6)mol·L^(-1)luminol standard solution containing 0.005 mol·L^(-1)sodium hydroxide was loaded into the above mixture, and the signal was recorded. It was speculated that potassium ferricyanide catalyzed the oxidation of luminol by dissolved oxygen to produce chemiluminescence under the alkaline condition, and the addition of paraquat increased the concentration level of the excited state of the luminol oxidation product 3-amino-phthalate ion, thus stronger light was emitted. Under the optimal conditions, linear relationships between the mass concentration of paraquat and its corresponding chemiluminescence intensity kept in the ranges of 5.0×10^(-4)^(-1).0×10^(-2)g·L^(-1)and 2.0×10^(-2)^(-1).0×10^(-1)g·L^(-1), with detection limit of 7.4×10-5g·L^(-1). Paraquat standard solutions were determined 11 times in parallel, and RSD of the determined values were not more than 5.0%. Test for recovery was made on the blank urine sample, giving results in the range of 96.4%^(-1)04%.