土壤中全磷测定方法的改进试验

Experiment on Improving Soil Phosphorus Test

土壤中磷的分析是土壤农化分析分析的主要项目之一。土壤全磷的测定方法之一原国标法GB9837-88,采用氢氧化钠熔融—钼锑抗混合试剂比色法在分析大批量的土壤样品时,存在着钼蓝颜色的稳定性超过30min之后较差,比色液容易出现混浊的现象。针对这种缺陷,作者对原国标法进行了改进土壤样品的分解采用目前赏用的HClO4—H2SO4消煮法,用草酸结合显色液中剩余的钼酸盐,使钼蓝的颜色稳定在7小时之内不变,再用异丁醇萃取显色液中的磷钼蓝。从而消除了由于样品混浊对比色测定的影响,在一定程度上提高了土壤全磷测定结果的精确度与准确度,方便了大批量的土壤全磷分析工作。

To analyze soil phosphorus is one of the main items to soil in agricultural chemistry. During one of the soil phosphorus test - the Original GB Bode Law GB 9837-88, using fused sodium hydroxide - the molybdenum stibium anti - mix reagent color method to analyze mass soil sample, the stability of the molybdenum blue misses when it surpasses 30 min and a muddy phenomenon is likely to appear in the colorimetric solution. In view of this kind of flaw, the author improved the Original GB Code Law: using the commonly used HClO4 - H2SO4 boiling method to discompose the soil sample; combining oxalic acid with the surplus molybdate in the colored fluid, the author tried to stabilize the molybdenum blue within 7 hours, and then used isobutyl alcohol to extract the phosphorus molybdenum blue from the colored fluid, thus to eliminate the influence upon the colorimetric determination caused by the turbid condition of the sample. And this can also enhance the accuracy and precision of the testing result in a certain degree and facilitate a large number of soil phosphorus analysis.