不同消解方式测定土壤中的全硼含量对比

Comparison of Different Digestion Methods for the Total Boron Determination in Soil

针对土壤中全硼测定存在难消解、干扰大、易挥发损失等问题,利用碱熔法、微波消解法以及微敞开石墨消解法对土壤全硼进行了测定分析,优化了消解条件,并对三种消解方式进行了验证对比。结果表明:碱熔剂种类以及用量会对碱熔法的准确性造成较大影响,选择KOH作为碱熔剂,并且KOH添加量为3.0 g时,可以获得更准确的结果;加酸种类以及赶酸温度的选择对微波消解法测定结果影响较大,选择加酸体系(5 mL HNO_(3)+1 mL HCl+3 mL HF+1.5 mL H_(3)PO_(4)),赶酸时温度选择170℃,测试效果较好;不同的加酸体系以及消解温度同样会引起微敞开石墨消解法测定结果出现较大误差,选择加酸体系(5 mL HNO_(3)+1 mL HClO_(4)+3 mL HF+1.5 mL H_(3)PO_(4)),消解温度设为170℃,测定结果更可靠。方法验证对比结果表明,碱熔法检出限为0.7 mg/kg,微波消解法检出限为0.9 mg/kg,微敞开石墨消解法检出限为1.0 mg/kg,均满足分析测定的要求。三种消解方式测定的准确度和精密度均符合要求,均可用于土壤全硼的测定,并且实际样品测定结果无显著性差异。三种消解方式优缺点和适用范围不同,实际测试时可以根据样品数量及样品中全硼大致含量等选择具体的消解方式。建立的方法可以为第三次全国土壤普查内业检测提供参考和借鉴。

In view of the problems of difficult digestion,large interference and volatile loss in the determination of total boron in soil,the alkaline melting method,microwave digestion method and micro-open graphite digestion method were used to detect and analyze the total boron in soil.The digestion conditions were optimized,and the three digestion methods were verified and compared.The results showed that the types of alkali fusion agent and the amount of alkali fusion had a great impact on the accuracy of the alkali fusion method.When KOH was selected as the alkali fusion agent and the addition amount of KOH added was 3.0 g,more accurate results could be obtained.The types of acid addition and the temperature of acid removal process had a major effect on the determination results of microwave digestion method.The optimal test results were obtained with acid addition system(5 mL HNO_3+1 mL HCI+3 mL HF+1.5 mL H_3PO_4) and acid removal temperature of 170 ℃.Different acid addition systems and digestion temperature also caused large errors in the determination results of micro-open graphite digestion method.When the acid addition system(5 mL HNO_3+1 mL HClO_4+3 mL HF+1.5 mL H_3PO_4) was selected,and the digestion temperature was set as 170 ℃.The determination results were more reliable.The verification and comparison results displayed that the detection limit of alkali fusion method was 0.7 mg/kg,the detection limit of microwave digestion method was 0.9 mg/kg,and the detection limit of micro-open graphite digestion method was 1.0 mg/kg,which all met the requirements of determination and analysis.Addition,the results of the three digestion methods exhibited satisfactory accuracy and precision,which could be used for the determination of total boron in soil,and there was no significant difference in the results of actual samples.The advantages and deficiency of the three digestion methods and the scope of application were different.In the actual test,the specific digestion method can be selected according to the number of samples and the approximate content of total boron in the sample.This work can provide reference for the 3rd National Soil Survey.