流动分析仪测定土壤有效磷含量的方法

Method for determination of effective phosphorus content in soil by flow analyzer

现有流动分析仪法测定碳酸氢钠浸提的有效磷低含量样品的准确性欠佳,难以适用于批量样品检测分析。为此提出改进方法,所测结果与现方法和人工比色法进行比较分析,探讨改进方法测定土壤有效磷的可行性。结果表明,现方法、人工比色法、改进方法测定有效磷含量在0.60~1 mg/L的样品,三者测定结果趋于一致,且无显著性差异(P>0.05)。现方法与人工比色法、改进方法测定有效磷含量0.04~0.60 mg/L的样品,现方法与另两种方法测定结果有显著性差异(P<0.05),人工比色法和改进方法测定结果无显著性差异(P>0.05)。人工比色法与现方法所测有效磷含量的回归方程:Y(人工比色法)=0.759X(现方法)+0.166(R2=0.811 P<0.01),两种方法所测有效磷呈极显著性相关。人工比色法与改进方法所测有效磷含量的回归方程:Y(人工比色法)=0.894X(改进方法)+0.024(R2=0.973 P<0.01),两种方法所测有效磷含量呈极显著性相关。综合比较,改进方法优于现方法。现方法的管路设置决定了碳酸氢钠与酸反应产生的二氧化碳气体会影响到管路气泡规则性和稳定性,造成基线易波动,有效磷低含量样品的准确性下降。改进方法的管路设置进行了优化,在线排除了二氧化碳气体,消除了干扰,保证了管路气泡的规则性,基线稳定,测定低含量有效磷的相对标准偏差小于8.90%,回收率在94%~106%之间,检测准确性和精密度良好。改进方法可推荐用于有效磷含量高低不同的批量土壤的检测分析。

The accuracy of the present flow analyzer method for determination of low content of effective phosphorus extracted from sodium bicarbonate was not good,and it was difficult to be used for batch samples detection and analysis.Therefore,an improved method was proposed.The results were compared with the present method and artificial colorimetric method,and the feasibility of determination of soil effective phosphorus by the improved method was discussed.The results showed that the results of the present method,artificial colorimetric method and improved method for the determination of effective phosphorus in the range of 0.60~1 mg/L tended to be consistent,and there was no significant difference(P>0.05).When the effective phosphorus content of the samples with 0.04~0.60 mg/L was determined by the present method,artificial colorimetric method and improved method,and the results of the present method were significantly different from those of the other two methods(P<0.05),while there was no significant difference between the results of the artificial colorimetric method and the improved method(P>0.05).The regression equation of effective phosphorus content measured by artificial colorimetric method and current method was Y(artificial colorimetric method)=0.759X(present method)+0.166(R2=0.811 P<0.01).There was a significant correlation between effective phosphorus content measured by two methods.The regression equation of effective phosphorus content measured by artificial colorimetric method and improved method was Y(artificial colorimetric method)=0.894X(improved method)+0.024(R2=0.973 P<0.01),and the effective phosphorus content measured by two methods showed an extremely significant correlation.Comprehensive comparison showed that the improved method was superior to the present method.The pipe setting of the present method determined that the carbon dioxide gas generated by the reaction between sodium bicarbonate and acid would affect the regularity and stability of the pipe bubble,resulting in the fluctuation of baseline,and the accuracy of samples with low effective phosphorus content would decrease.The pipeline settings of the improved method were optimized,carbon dioxide gas was eliminated online,interference was eliminated,the regularity of pipeline bubbles was guaranteed,and the baseline was stable,the relative standard deviation of the determination of low content effective phosphorus was less than 8.90%,and the recovery was between 94%~106%.The detection accuracy and precision were good.The improved method could be recommended for the detection and analysis of batch soil samples with different contents of effective phosphorus.