电感耦合等离子体发射光谱法(ICP-OES)测定海洋浮游生物中总磷的方法优化

磷作为海洋浮游生物生长必需营养元素之一,其准确测定对海洋生态系统元素循环过程的研究具有重要意义。目前,文献中对于海洋浮游生物中总磷的测定方法报道不多。由于海洋浮游生物生存的高盐海洋环境,高盐基体的存在导致常规检测方法不能准确测定磷的含量。为剔除高盐基体效应及干扰,本文运用微波密闭消解预处理样品,采用电感耦合等离子体发射光谱法(ICP-OES)联合标准加入法建立工作曲线,同时结合样品的特异性,对ICP-OES分析谱线、射频功率、雾化气流速、观测高度、蠕动泵泵速和观测方式等仪器参数进行优化,构建确定了准确测定海洋浮游生物中总磷的优化条件和技术流程。实验结果显示, ICP-OES最佳工作条件为分析谱线P213.617 nm,射频功率1 300 W,雾化气流量0.8 L/min,观测高度14mm,进样泵速1.5 m L/min,观测方式轴向。标准加入法标准曲线相关系数大于0.999,相对标准偏差为1.36%～1.67%,加标回收率为92.6%～94.3%,方法检出限为0.010 mg/L,检测结果具有较高的准确度和精密度,可为海洋浮游生物及其它高基体生物样品中磷含量的准确测定提供技术支持。

Optimization of ICP-OES for the determination of total phosphorus in marine plankton

Phosphorus is one of the essential nutrient elements for the growth of marine plankton. The accurate determination of phosphorus is of great significance to the study of the cycling process of elements in the marine ecosystem. At present, few reports on the determination of total phosphorus in marine plankton are available. Because of the high salt environment in which marine plankton exists, the content of phosphorus cannot be accurately determined by conventional methods due to the presence of a high salt matrix. To eliminate the high salt matrix effect and its interference, the optimized conditions and technical process for the accurate determination of total phosphorus in marine plankton were established. The experimental sample was pretreated by microwave digestion, and the working curve was established by inductively coupled plasma emission spectrometry (ICP-OES) combined with the standard addition method. The results showed that the optimum operating conditions of ICP-OES were as follows:analytical spectrum line, P213.617 nm; RF power, 1300 W; nebulizer gas flow, 0.8 L/min; viewing height, 14 mm; sample introduction rate, 1.5 mL/min; the observation mode was axial. The correlation coefficient of the linear regression equation was greater than 0.999. The relative standard deviations were ~1.36% and ~1.67% and the recovery rates of the method were ~92.6% and ~94.3%. The detection limit of the method was 0.010 mg/L. The results had high accuracy and precision, which could provide technical support for the accurate determination of phosphorus in marine plankton and other high matrix samples.