4-硝基邻苯二胺缩水杨醛分光光度法测定水中微量钴(Ⅱ)

Determination of micro cobalt(Ⅱ)in water by 4-nitro-o-phenylenediamine-salicylaldehyde spectrophotometry

随着工业的发展,钴污染问题日益显现,对人类健康和地球生态系统构成一定的威胁,钴的监测亟待加强。由于分光光度法具有操作简单、响应速度快、选择性好、灵敏度高和成本低廉等优点而受到人们的青睐,开发新型的显色体系可以为钴的检测提供更多方便有效的检测方法。实验研究了4-硝基邻苯二胺缩水杨醛(NPDAS)与钴(Ⅱ)的显色反应,在2.0mLNa2CO3-NaHCO3缓冲液(pH 9.60)中,NPDAS与钴(Ⅱ)生成物质的量比为1∶1的红色络合物,于530nm处有最大吸收峰。钴(Ⅱ)的质量浓度为0.06~0.47mg/L时,与吸光度呈线性关系,相关系数为0.996 1。方法检出限为0.03mg/L,表观摩尔吸光系数为3.8×104 L·mol-1·cm-1。方法用于水中微量钴(Ⅱ)的测定,结果的相对标准偏差(RSD,n=6)为2.3%~3.8%,加标回收率为95%~105%,测定值与原子吸收光谱法(AAS)测定值基本一致。

With the development of industry,the problem of cobalt pollution had become more and more serious,which posed a certain threat to the ecosystem of human health and the earth.The monitoring of cobalt should be strengthened.The spectrophotometry had attracted more and more attention due to its advantages such as simple operation,fast response,good selectivity,high sensitivity and low cost.The development of new coloring systems could provide more effective and convenient detection methods for the detection of cobalt.The color reaction between 4-nitro-o-phenylenediamine-salicylaldehyde(NPDAS)and cobalt(Ⅱ)was studied.In the buffer solution of 2.0mL Na2CO3-NaHCO3(pH 9.60),NPDAS could react with cobalt(Ⅱ)to form a red complex with molar ratio of 1∶1,which had maximum absorption peak at530nm.The mass concentration of cobalt(Ⅱ)in range of 0.06-0.47mg/L had good linear relationship with the absorbance,and the correlation coefficient was 0.996 1.The limit of detection was 0.03mg/L.The apparent molar absorptivity was 3.8×104 L·mol-1·cm-1.The proposed method was applied for the determination of trace cobalt(Ⅱ)in water.The relative standard deviations(RSD,n=6)of determination results were between 2.3%and 3.8%.The spiked recoveries were between 95%and 105%.The found results were basically consistent with those obtained by atomic absorption spectrometry(AAS).