Khalaf K D, Sancenon J, de la Guardia M
Department of Analytical Chemistry, University of València, Dr Moliner 50, 46100 Burjassot, València, Spain.
Talanta. 1993 Aug;40(8):1173-81. doi: 10.1016/0039-9140(93)80184-s.
An automated procedure has been developed for the determination of formetanate and its metabolite m-aminophenol (MAP) in water samples. MAP can be selectively determined in the presence of formetanate by direct on-line reaction with p-aminophenol and spectrophotometric measurement of the absorbance at 576 nm in the presence of KIO(4), as oxidizing agent. The method has a limit of detection of 5 x 10(-7)M, it provides a recovery percentage from 95 to 104% and permits one to carry out 120 measurements/hr. The spectrophotometric determination of formetanate must be carried out after a previous hydrolysis to MAP. To determine formetanate in the presence of MAP, two steps are necessary. Firstly, the MAP content is selectively determined as has been mentioned above. After that, the sample is treated with 0.05M NaOH at 90' degrees C, to hydrolyze the formetanate to MAP, and then the sum of both is determined spectrophotometrically. The difference between the results obtained in each step gives the formetanate concentration. The developed procedure for the determination of formetanate provides a sensitivity of 1070 absorbance units mol(-1) l and a limit of detection of 1.9 x 10(-7)M, which corresponds to 50 mug/l of formetanate hydrochloride. The method has been applied to the analysis of natural water samples fortified with formetanate and MAP, and formetanate has also been quantitatively recovered in irrigation waters at a concentration level of 1.9 x 10(-6)M which corresponds to 500 mug/l. On the other hand, working in the stopped-flow mode, for a reaction time of 100 sec, the sensitivity of the formetanate determination can be increased to 4642 absorbance units mol(-1) l but the limit of detection remains of the order of 44 mug/l.
已开发出一种自动化程序，用于测定水样中的伐虫脒及其代谢物间氨基酚（MAP）。在有伐虫脒存在的情况下，通过与对氨基酚直接在线反应，并在作为氧化剂的KIO(4)存在下，于576 nm处进行吸光度的分光光度测量，可选择性地测定MAP。该方法的检测限为5×10(-7)M，回收率为95%至104%，每小时可进行120次测量。伐虫脒的分光光度测定必须在预先水解为MAP后进行。要在有MAP存在的情况下测定伐虫脒，需要两个步骤。首先，如前所述选择性地测定MAP含量。之后，将样品在90℃下用0.05M NaOH处理，使伐虫脒水解为MAP，然后通过分光光度法测定两者之和。每一步所得结果的差值即为伐虫脒浓度。所开发的伐虫脒测定程序的灵敏度为1070吸光度单位mol(-1) l，检测限为1.9×10(-7)M，相当于50μg/l的盐酸伐虫脒。该方法已应用于添加了伐虫脒和MAP的天然水样分析，在浓度为1.9×10(-6)M（相当于500μg/l）的灌溉水中也能定量回收伐虫脒。另一方面，在停流模式下工作，反应时间为100秒时，伐虫脒测定的灵敏度可提高到4642吸光度单位mol(-1) l，但检测限仍约为44μg/l。
