流动注射分析法和传统方法测定土壤中N的比较研究

为了对FIAstar 5000流动注射分析仪和传统方法(氧化镁浸提.扩散法、酚二磺酸比色法和镀铜镉还原-重氮化耦合比色法)的分析结果进行比较,分别采用此两种方法测定了同一流域内不同利用类型土壤中铵态氮、硝态氮和亚硝态氮的含量,通过样品均值、测试误差、回收率和标准偏差等指标对两种方法进行了比较研究.结果表明,流动注射分析仪在测定土壤中铵态氮和硝态氮时,分析速度快且仪器具有较好的稳定性(5次平行次数内结果RSD<5%).从分析结果的准确性看,采用流动注射分析仪分析土壤中铵态氮、硝态氮时,与传统方法也具有可比性,样品回收率分别为98.5%～102.0%和96.7%～98.3%.在测定土壤亚硝态氮时,流动注射分析法仪器稳定较差(5次平行次数内结果RSD>6%),且分析结果普遍偏低,需要进行必要的校正.因此,在大批量测定土壤样品铵态氮、硝态氮时,用流动注射分析法是可行的,但测定亚硝态氮含量时,存在较大的误差,需要进行校正.

Comparison of Flow Injection Analysis Method and Traditional Methods for the Determination of Nitrogen in Soils

The contents of NH4+-N, NO3--N and NO2--N in different use types of soil from the same valley were determined using flow injection analysis method (FIAstar 5000) and traditional methods (MgO extraction and diffusion method, phenoldisulfonic acid colorimetry method and copperized cadmium reduction method), respectively. The average value, the determined error, the recovery rate and standard deviation were compared between the two methods. The result shows that flow injection analysis method is more rapid than traditional method and has a good stability in the determination of NH4+-N and NO3--N in soil (RSD <5%, n=5). Flow injection analysis method is also comparable with the recovery rate 96.7~98.3% and 98.5~102.0%. However, the flow injection analyser is unstabler than phenoldisulfonic acid colorimetry method in determination of NO2--N in soil (RSD>6%, n=5), and the analysis results are generally lower than true value and need to carry out the necessary correction. Therefore, if we measure NH4+-N and NO3--N in large amount soil samples, using the flow injection analyser is feasible, but when measuring the NO2--N content, there is a significant error existed and need to be corrected.