流动注射—光度法联用测定海水中PO4-P

本法针对海水分析时严重的盐度和基体干扰,以监测的海水试样为载流,并在流动注射进样阀前流路上首次引入自制全容量阴离子交换柱,去除载流中的磷酸盐,使进入系统的载流盐度与试样一致,消除了基体干扰,并通过阴柱在线再生条件试验和工作曲线优化试验,建立了流动注射磷锑钼蓝(还原剂为抗坏血酸)光度法直接测定PO4-P浓度为Ⅰ类～Ⅳ类海水的新方法,能分辨海水类别。结果表明,在最适合条件下,该方法在PO4-P浓度5～80μg/L范围内峰高与浓度成线性关系,方法检出限为0.73μg/L,空白海水加10μg/L、30μg/L和60μg/L PO4-P标准物质连续进样,RSD分别为4.57%(n=5)、4.72%(n=4)和5.76%(n=4)。进行实际样品分析时,加标回收率为101%～102%,具有很好的准确性,与国家标准方法———磷钼蓝分光光度法比对,结果吻合,令人满意。

Determination of PO4-P in Seawater with Flow-injection Spectrophotometric Analysis

A new method was proposed to determine PO4-P in seawater from first to fourth class based on the combination of phosphorus antimony molybdenum blue photometry （deoxidized reagent is L-axrobie acid） and flow injection analysis. In this method, the seawater sample analyzed was used as carrier, and an anion ion exchange eolumn was connected to the cartier flow before the six-way automatic injection valve to remove the PO3^2- in seawater to make sure that the earrier flew in analysis system had no PO3^2-, and the salinities of carrier used and the sample analyzed were same to eliminate the Matrix Interference. The results showed that, under the optimal conditions, the peak height was truly linear versus PO4-P concentrations within the range of 5.0 - 80. 0μg/L, the detection limit of this method was 0. 73μg/L, and the relative standard deviations （RSD） was 4. 57% （n=5）, 4.72% （n =4） and 5.76% （n =4） versus 10μg/L, 30μg/L and 60μg/L PO4-P solution prepared by bland seawater. The result was of in good agreement with phosphorus molybdenum blue photometry and satisfied with recovery percentages of 101% - 102% using this method to analyze the PO4-P in seawater.