微波消解-流动注射法测定海水中总磷

Determination of total phosphorus in seawater by microwave digestion-flow injection spectrophotometry

为了实现实时监测近岸海域海水中的总磷水平,采用微波消解-流动注射-紫外分光光度法进行测定,并通过控制程序实现连续测定。优化了消解条件、进液顺序和显色剂质量浓度等实验条件,并在最佳实验条件下测定的海水中总磷浓度与吸光度呈良好线性关系。标准样品检验的相对标准偏差(RSD)为4.095%,样品的加标回收率在95%~98%之间。研究方法稳定性的检测结果显示,零点漂移在±0.1%之内,量程漂移在±3%之内,符合《近岸海域水质自动监测技术规范》(HJ731—2014)的要求。用微波消解-流动注射-紫外分光光度法测定的大连老虎滩表层海水中总磷的质量浓度为0.068 9 mg/L,与国标法(GB/T 12763.4—2007)测定结果(0.069 3 mg/L)无显著性差异。因此,该测定方法可用于快速测定海水中总磷的含量,为实现海水富营养化的预警监测提供可靠数据。

In order to monitor the total phosphorus level in the coastal waters in real time. A method for determination of total phosphorus in water by digestion and flow injection spectrophotometry is described. Total nitrogen is determined continuously by controlling program in the coastal area. Effects of experimental conditions have been optimized,including the digestion condition,the order of liquid and the mass concentration of the color developing agent. Under the optimal conditions,the concentration of phosphorus in seawater is in good linear relation with absorbance. The relative standard deviations(RSD) of TP is less than 4.095%. The standard addition recoveries of TP are from 95% to 98%.The method has high sensitivity as well as precision. Zerodrift rate and range drift rate are less than ±0.1% and ± 3% respectively. The determination results agree well with those obtained by the specification for automated waterquality monitoring in coastal area(HJ 731—2014). The determination of total phosphorus in surface waters of Dalian Tiger Beach concentration of 0.068 9 mg/L,0.069 3 mg/L with national standard method(GB/T 12763.4—2007) of measurement results. There is no significant difference. The determination results agree with those obtained by the national standard method. The content of total phosphorus in seawater can be quickly determined by this method. It provides reliable data for the eutrophication of sea water and realize early warning and monitoring.