基于酸碱滴定法的土壤中碳酸氢根测定方法改进  

Improvement of the Method for Determining Bicarbonate in Soil based on Acid-base Titration

作　　者：操凤 崔文文 姚晶晶[1] 王明锐[1] 路磊[1] 王爱华[1] 张惠贤[1] CAO Feng;CUI Wenwen;YAO Jingjing;WANG Mingrui;LU Lei;WANG Aihua;ZHANG Huixian(Institute of Agricultural Quality Standards and Testing Technology Research/Laboratory of Quality&Safety Risk Assessment for Agro-products/Hubei Key Laboratory of Nutritional Quality and Safety of Agro products,Hubei Academy of Agricultural Sciences,Wuhan 430064;Hubei Agro-Science Quality Standard and Testing Technology Co.,Ltd.Wuhan 430064)

机构地区：[1]湖北省农业科学院农业质量标准与检测技术研究所/农业农村部农产品质量安全风险评估实验室/农产品营养品质与安全湖北省重点实验室,湖北武汉430064 [2]湖北农科质标检测科技有限公司,湖北武汉430064

出　　处：《分析科学学报》2023年第6期732-736,共5页Journal of Analytical Science

基　　金：湖北省自然科学基金项目资助(No.2021CFB063)。

摘　　要：本文建立了普通去离子水提取-双指示剂-酸碱滴定法测定土壤中HCO_(3)^(-)含量的方法。以不同性质的浸提用水配制HCO_(3)^(-)溶液,甲基红-溴甲酚绿混合指示剂指示终点,计算盐酸标准溶液滴定HCO_(3)^(-)的终点误差,结果表明,终点误差分别在0.1%~1.3%和-0.047%~-0.148%之间。对甲基红与溴甲酚绿混合指示剂的配比和用量进行了优化。在优化条件下,土壤中HCO_(3)^(-)添加回收率在98.7%~104.1%之间,日内、日间相对标准偏差低于10.1%,有证标准物质测定值的误差在-7.0%~8.3%,说明本方法具有很好的准确度和精密度。本研究解决了现行标准中土壤浸提用水需要煮沸除CO_(2),滴定终点难以确定的问题,具有简便、快速且准确的优点,适用于大批量土壤样品HCO_(3)^(-)的同时分析。A method was developed for the determination of bicarbonate content in soil by ordinary deionized water extraction-bis-indicator-acid-base titration.The HCO_(3)^(-)solution was prepared in extracted water with different properties,and the end point was indicated by the mixed methyl red-bromocresol green indicator.The titration errors of the standard solution of hydrochloric acid for the titration of HCO_(3)^(-)were calculated,and the results showed that the titration errors ranged from 0.1%to 1.3%and-0.047%to-0.148%,respectively.The ratio and dosage of the mixed indicator of methyl red and bromocresol green were optimized.Under the optimized conditions,the recovery of HCO_(3)^(-)in soil was between 98.7%and 104.1%,and the relative standard deviation was less than 10.1%in intra-day and inter-day analyses.The relative errors of the determination value of the certified reference materials was between-7.0%and 8.3%,indicating good accuracy and precision of this method.This study solved the problem in the current standard that the water used for soil extraction needs to be boiled to remove CO_(2)and the titration endpoint is difficult to be determined.This method is simple,fast,and accurate,and suitable for the batch analysis of a large number of soil samples for HCO_(3)^(-).

关 键 词：土壤 碳酸氢根 混合指示剂 滴定 改进 

分 类 号：O655.22[理学—分析化学]