[Determination of anionic synthetic detergent in drinking water by methylene blue spectrophotometry].

OBJECTIVE

To develope a method for rapid determination of anionic synthetic detergent in drinking water by methylene blue spectrophotometry.

METHODS

Added 20. 0 mL water sample into 50 mL plastic tube, then added 10. 0 mL chloroform and 200 μL methylene blue solution, oscillatied 1 min, layering, suck out the upper solution, calibrated zero using chloroform, determinated the absorbance of the bottom extraction solution at 650 nm wavelength.

RESULTS

The regression equations of the rapid determination method showed a good linearity and the correlation coefficient was 0. 9995. The method minimum mass detection concentration was 0. 05 mg/L. The recoveries were between 92. 7% and 98. 3%, and the relative standard deviations were between 4. 8% and 5. 7%(n=6). Compared with the national standard method by significance test, the significant difference had no statistical significance(P=0. 79). The detection time(30 samples) was only 2 h which needed a day by using national standard method. The concentration range of anionic synthetic detergent of 30 samples in the Yanqing urban areas of Beijing were<0. 05-0. 26 mg/L.

CONCLUSION

This method is simple, sensitive, accurate and efficient, and it is suitable for basic level laboratories rapid determination and drinking water surveillance.