加热灰化法在有机肥磷含量测定中的应用

Application of Heating Ashing Method in Determination of Phosphorus Content in Organic Fertilizer

国家行业标准中,有机肥样品用浓硫酸-过氧化氢消煮,硫酸将有机质碳化,试样处理时需静置过夜,耗时长,所得试液用分光光度法—磷钒钼黄比色法测定磷含量。加热灼烧有机肥可使有机质快速灰化,再用少量酸和氧化剂酸化处理灰化样品,将其中的磷完全溶解并转化成磷酸根离子。与浓硫酸-过氧化氢消煮试样相比,加热灰化法处理样品,分光光度法测得磷含量的相对标准偏差在1.80%~2.45%,提高了检验效率,操作简单便捷。同时增大了称样量,提高了待测液中磷含量,用沉淀法测定磷含量可以增加沉淀量,适用于磷钼酸喹啉沉淀法测定有机肥中磷,满足有机肥厂为控制产品质量而进行的日常检测。

In the current national industry standards,organic fertilizer is digested with concentrated sulfuric acid and hydrogen peroxide,sulfuric acid carbonizes organic matter,the sample shall be left to stand overnight,the process is taking a long time,the obtained test solution of phosphorus is determined by spectrophotometry-phosphorus vanadium molybdenum yellow colorimetry.Heating and firing organic fertilizer can quickly ashing organic matter,the ashing sample is acidified with a small amount of acid and oxidant,to completely dissolve the phosphorus in the test solution and convert it into phosphate ions.Compared with sulfuric acid concentrated boiling hydrogen peroxide sample,treatment of samples by heating ashing,the relative standard deviation of phosphorus content measured by spectrophotometry is 1.80%-2.45%,the inspection efficiency is improved and the operation is simple.At the same time,the sample weight is increased,the phosphorus content in the solution to be measured is increased,the test solution can be used to determine phosphorus in organic fertilizer by quinoline phosphomolybdate precipitation method.It is convenient for the central control analysis of organic fertilizer manufacturers.