电感耦合等离子体发射光谱(ICP-OES)法测定石灰性土壤中交换性盐基K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)

Determination of Exchangeable Bases K^(+),Na^(+),Ca^(2+)and Mg^(2+)in Calcaric Soil by Inductively Coupled Plasma Optical Emission Spectrometry(ICP-OES)

石灰性土壤的交换性盐基常规检测方法过程手续繁琐、乙醇消耗量大、交换液过滤淋洗定容至250 mL容量瓶耗时过长。通过改变取样量和氯化铵-乙醇交换液的比例关系,选择合适的震荡时间,一次性交换完全,直接干过滤部分提取液到25 mL比色管中,再将滤液转移至聚四氟乙烯烧杯中,电热板加热挥发掉乙醇,用盐酸提取,使得乙醇体系转换为盐酸体系,减少了乙醇的用量、缩短了前处理时间、解决了等离子体引入有机物熄火的问题,建立了电感耦合等离子体发射光谱(ICP-OES)法直接测定石灰性土壤盐基中K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)的方法。选用4个石灰性土壤有效态国家一级标准物质按照所建立的方法进行处理,测定结果均在认定值的误差范围内;采用8个全国第三次土壤普查实际样品与标准方法进行比对实验,各组分检测结果无显著差异。各元素的光谱强度在0~100μg/mL呈良好的线性关系,线性相关系数(r)均在0.999 9以上,方法检出限值为0.004~0.015 cmol/kg,相对标准偏差RSD(n=12)为0.74%~8.5%。满足第三次全国土壤普查全程质量控制规范中对石灰性土壤基盐检测质量技术要求。

The conventional detection method for exchangeable salts in calcareous soil is cumbersome,inefficient,and consumes a large amount of ethanol.By changing the sample size and the ratio of ammonium chloride ethanol exchange solution,selecting an appropriate shaking time,the exchange solution is directly filtered dry into a 25 mL colorimetric tube,and then transferred to a polytetrafluoroethylene beaker.The ethanol is evaporated by heating with an electric heating plate,and then extracted with hydrochloric acid to convert the ethanol system into a hydrochloric acid system,solving the problem of plasma induced ethanol quenching,and thus a method for direct determination of K^(+),Na^(+),Ca^(2+)and Mg^(2+)in calcareous soil by inductively coupled plasma emission spectrometry(ICP-OES)was established.Four national first-class standard substances for the effective state of calcareous soil were selected and processed according to this method,and the measurement results were all within the error range of the recognized values.A comparative experiment was conducted using 8 actual samples from the third national soil survey and standard methods,and there was no significant difference in the detection results of each component.The spectral intensity of each element ranged from 0 to 100μg/mL.There was a good linear relationship within the concentration range of g/mL,with correlation coefficients(r)above 0.9999.The detection limit of the method was 0.004—0.015 cmol/kg,and the relative standard deviation(RSD)(n=12)was 0.74%—8.5%,which meeting the technical requirements for the quality control of calcareous soil base salt testing in the entire process of the third national soil survey.