Rapid Field Analysis of Silver by Sulfhydryl Cotton Preconcentration- Fiber Optic Spectrophotometry with Ag-TMK-DBS Ternary Complex

A rapid field fiber-optic spectrophotometric method for determination of silver based on the chromogenic reaction of silver with TMK-DBS was developed. The sample was digested with nitric acid and sulfhydryl cotton was added into the sample solution to separate Ag from the interference elements. In buffer solution of HAc-NaAc (pH 4.5), Ag reacted with TMK and DBS to form a water-soluble red ternary complex. Absorbance of the ternary complex was determined by a fiber-optic spectrophotometer at 540 nm. Some factors affecting the silver analysis were studied. The detection limit(3s)of method was 0.10 μg/g for Ag. The recovery of the method was 96.0%~99.4% with precision of less than 5.76% RSD (n=11). The method has been applied to the determination of silver in National Standard Reference samples. The results are in agreement with certified values and comparable with those from the indoor analysis by AAS in accuracy and precision.