过硫酸钠同时消解养殖尾水中总氮和总磷的探索

Exploration of Sodium Persulfate for Simultaneous Digestion of Total Nitrogen and Total Phosphorus in Aquaculture Tailwater

大部分池塘养殖尾水中总氮、总磷质量浓度偏高,测定过程中需要对样品进行稀释,耗时较长且影响准确度。实验室分析时,通常采用过硫酸钾对尾水样品进行消解,其配置过程对温度要求较高,易析出晶体,且耗时较长。而过硫酸钠易溶于水,受温度影响较小,易配制。因此,分别采用上述2种过硫酸盐消解液对样品进行消解并同时测定总氮、总磷的质量浓度,比较2种消解方式对校准曲线、加标回收率、养殖尾水实际样品测定的影响。结果表明,等质量或等物质的量的过硫酸钠消解液均能满足总氮、总磷的消解要求,且后者消解样品无须改变氢氧化钠的加入量和调整pH值,即可达到同等消解效果。因此,可采用等物质的量的过硫酸钠代替过硫酸钾同时消解养殖尾水中的总氮、总磷。

The total nitrogen and total phosphorus content of tailwater from aquaculture ponds is usually high. Thus, samples need to be diluted before measurement, which leads to an increase in measurement time and a decrease in measurement accuracy. In the laboratory, potassium persulfate is commonly used for digestion of tailwater samples. The disadvantages of potassium persulfate are that it is easy to precipitate in crystal form at low temperature and its preparation is time-consuming. On the contrary, sodium persulfate is easily soluble in water, less affected by temperature and easy to prepare. In this study, the samples were digested by two kinds of persulfate digestion solutions, respectively, and the contents of total nitrogen and total phosphorus of the digested samples were determined, so as to compare the effects of the two methods on calibration curves, standard recovery, and determination of aquaculture tailwater samples. It was found that when the mass or amount of substance is equal to potassium persulfate, the sodium persulfate digestion solution can meet the requirements of total nitrogen and total phosphorus digestion. Moreover, the amount of sodium hydroxide added, and pH need not be adjusted when using sodium persulfate digestion solution, and the digestion effect is equal to that of potassium persulfate under equal mass or equal amount of substance. In conclusion, equal amount of substance of sodium persulfate can replace potassium persulfate for digestion of total nitrogen and total phosphorus in aquaculture tailwater samples.