FI-Spectrophotometric Determination of the Herbicide Acetochlor in Water with On-line Liquid Membrane Enrichment

The liquid membrane extraction system containing octanol and Span 80 in kerosene was applied to the on-line enrichment of a herbicide,acetochlor,in water,the decomposition pruduct of which was determined in the inner phase solution of NaOH UV-spectrophotometrically at the wavelength of 214 nm.It was found that the optimum proportion of components in the liquid membrane system was octanol to Span 80 to kerosene equalling to 12 to 1 to 87 (volume fraction),and that the pH-values of outer phase and inner phase solutions were pH 7 and pH 12 respectively.Time of enrichment taken was 7 min.Under these conditions,linear relationship was obtained in the range of 1-10 μg·L-1 of acetochlor in respective to their values of absorbance.Detection limit (3S/N) of 0.3 μg·L-1 was obtained for the method.In analyzing 3 samples of environmental water by the proposed method,value of average recovery found was 98%,with values of RSD′s (n=5) less than 4%.