多功能水质分析仪中COD替代试剂的研制

为了降低COD测定成本,减小试剂污染,介绍了一种测定量程为0～1 500 mg/L的HACHCOD替代试剂.重点讨论了组分配比、标准曲线、消解管磨损等因素对测定结果的影响,并提出一系列提高测定质量,减少测定误差的措施.该替代试剂配比为0.5 mL 1/6 K2Cr2O7 (1.00 mol/L) 2.5 mL 1% H2SO4-Ag2SO4 0.04 g HgSO4,在组成上接近于HACH原装试剂,使用内置程序测定的误差介于2.79%～5%之间,使用对应的程序测定误差为0.23%～2.64%.实验证明,与HACH原装试剂、传统重铬酸钾法相比,该替代试剂在测定准确度方面无明显差异,3种方法的平均变异系数分别为1.87%、2.37%和3.71%,测定精密度满足要求, t 均小于 t 0.95,测定结果准确可靠.经济技术比较显示替代试剂具有操作简单,成本低,污染小,适合批量测定等优势.单个样品的平均测定成本仅为0.78 元.

A substitutional COD re-agent for mutlti-functional water quality analyzer

This paper is aimed at introducing a substitutional reagent developed by the present authors with 01 500 mg/L of COD for multi-functional water quality analyzer so as to reduce the testing cost and agent pollution.The substitute is actually composed of the following components:0.5mL 1/6 K_2Cr_2O_7(1.00mol/L)+2.5 mL 1% H_2SO_4-Ag_2SO_4 + 0.04g HgSO_4.From the above illustration,it can be seen that the substitute is similar by nature to HACHCOD kit.Its measuring error rate ranges from 2.79% to 5% when tested by the inside program,and 0.23%2.64% when tested by its own program.As compared with other current COD measuring methods,such as HACHCOD kit and titration method of K_2Cr_2O_7,no difference can be found between the present substitute and the other related methods.The experiment results prove that the accuracy rate of the substitute appears close to that of HACHCOD kit and creditable.CV of the three methods are 3.71%,2.37% and 1.87%,with the precision of substitutional reagent being high and satisfied.The t value of the substitute proves lower than t_ 0.95 with the measuring results being accurate and advantageous in a few aspects.For example,it is simple in operation,lower in measuring costs along with lower environmental pollution.Therefore,it is available for the substitute to be used in the cases of large amounts of wastewater sample to be measured.The likely factors to influence the measurement accuracy have also been discussed in the last part of the paper,such as the composition of the substitute,standard curves and abrasion of digestive tubes and so on.Steps or procedures to be taken have also been presented for the users to increase their measuring accuracy.