恒压氮气隔断连续流动分析法测定水中化学需氧量

为建立恒压氮气隔断连续流动分析法测定水样化学需氧量的分析方法，将连续流动分析法恒流空气隔断改为恒压氮气隔断，优化试剂配方和反应模块，结果表明：恒压氮气隔断法注入氮气的压力是0.06 MPa,仪器稳定时间是20～35 min,持续分析样品时间大于4 h,指标均优于恒流空气隔断法；标准曲线在2.5～40.0 mg/L范围内，相关系数大于0.999,方法检出限为0.44 mg/L,相对标准偏差为0.2%～2.6%,加标回收率在93.8%～103.8%之间，检出限优于恒流空气隔断法，精密度和正确度满足质量控制要求；实样和标样方法比对测定结果相对标准偏差小于5%,结果精密度优于标准的手工法。恒压氮气隔断连续流动分析法适用于大批量低浓度水样化学需氧量的快速检测，对于密度大、黏度大液流恒压氮气隔断具有更好的稳定性、灵敏度和正确度。

Determination of Chemical Oxygen Demand in Water by Constant Pressure Nitrogen Partition Continuous Flow Analysis

In order to establish an analytical method for the determination of chemical oxygen demand in water by constant pressure nitrogen partition continuous flow analysis.The continuous flow analysis constant flow air partition was changed to a constant pressure nitrogen partition,and the reagent formula and reaction module were optimized.The Results showed that the pressure of the nitrogen injected by the constant pressure nitrogen partition method is 0.06 MPa.The instrument stabilization time is 20-35 min.The continuous sample analysis time is more than 4 hours.The indicators are better than the constant flow air partition method.The standard curve is 2.5-40.0 mg/L concentration range,the correlation coefficient is greater than 0.999,the detection limit of the method is 0.44 mg/L,the relative standard deviation is 0.2%-2.6%,the recovery rate of standard addition is between 93.8%-103.8%,and the detection limit is better than the constant flow air partition method,and the precision and correctness meet the quality control requirements.The relative standard deviation of the results of the comparison between the real sample and the standard sample method is less than 5%,and the precision of the result is better than the standard manual method.The constant pressure nitrogen partition continuous flow analysis method is suitable for the rapid detection of chemical oxygen demand in large quantities of low-concentration water samples.It has better stability,sensitivity and correctness for the partition of constant pressure nitrogens in high-density,high-viscosity liquid flows.