超声浸提-分光光度法测定土壤阳离子交换量

Determination of Soil Cation Exchange Capacity by Ultrasonic Extraction-Spectrophotometry

为准确测定土壤阳离子交换量,在三氯化六氨合钴[Co(NH_(3))_(6)]Cl_(3)浸提-分光光度法研究的基础上,采用超声浸提代替传统的振荡浸提。确定了在40 mL浸提液中加入2.8 g土壤样品,用1 mol/L氢氧化钠调节溶液pH值至8±0.5,超声浸提10 min,用滤纸过滤代替离心,1.66 cmol/L[Co(NH_(3))_(6)]Cl_(3)溶液直接作为空白样品的实验条件。结果表明,方法在0~1.49 cmol/L范围内具有良好的线性,线性系数为1;方法检出限为0.7 cmol+/kg,方法定量下限为2.8 cmol+/kg;10种土壤标准物质的测定结果均在认证值范围内,相对标准偏差(n=6)在0.28%~2.7%,具有良好的精密度和准确度。超声浸提-分光光度法测定土壤阳离子交换量准确可靠,操作过程简单,提高了工作效率,可应用于批量土壤阳离子交换量样品的检测。

In order to accurately determine the cation exchange capacity of soil,based on the study of hexaammine cobalt trichloride leaching-spectrophotometry,ultrasonic leaching was used instead of traditional oscillation leaching.It was determined that 2.8 g of soil samples were added to 40 mL of leaching solution,the pH of the solution was adjusted to 8±0.5 with 1 mol/L sodium hydroxide,ultrasonic extraction was performed for 10 min,and filter paper was used instead of centrifugation.1.66 cmol/L[Co(NH_(3))_(6)]Cl_(3) solution was directly used as the experimental condition of blank sample.Validate the experimental conditions and test methods.The results show that the method has good linearity in the range of 0-1.49 cmol/L,the linear coefficient is 1;the detection limit of the method is 0.7 cmol+/kg,and the lower limit of quantification of the method is 2.8 cmol+/kg.The determination results of 10 soil reference materials are all within the certified value range,and the relative standard deviation(n=6)is 0.28%-2.7%,with good precision and accuracy.The ultrasonic extraction-spectrophotometry method is accurate and reliable for the determination of soil cation exchange capacity,the operation process is simple,and the efficiency is improved.It can be applied to the detection of batch soil cation exchange capacity samples.