亚甲蓝分光光度法快速测定生活饮用水中阴离子合成洗涤剂

目的建立生活饮用水中阴离子合成洗涤剂的快速测定法。方法取水样20.0 mL于50 mL塑料离心管中,加入10.0 mL三氯甲烷和200μL亚甲蓝显色液,振荡1 min静置分层,用滴管吸出上层溶液,于650 nm波长,用三氯甲烷溶液校零,测定下层萃取液的吸光度从而计算阴离子合成洗涤剂的含量。结果本方法改进的亚甲蓝分光光度法快速测定饮水中阴离子合成洗涤剂线性关系良好,相关系数(r)为0.9995,最低检测质量浓度为0.05 mg/L,对样品进行低、中和高三个浓度水平的加标实验,回收率为92.7%～98.3%,精密度为4.8%～5.7%(n=6),与国标方法比对进行显著性检验,差异无统计学意义(P=0.79)。完成使用国标方法测定一天的实验工作量(30份水样)的检测时间仅需2 h。在测定的30份北京市延庆区城区自来水样品中,阴离子合成洗涤剂的浓度范围为<0.05～0.26 mg/L。结论本检测方法操作简便、快速、准确,适合基层实验室现场检测以及饮用水监测。

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 200μL 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.