恒温振荡浸提-火焰原子吸收光谱法测定土壤中铬(Ⅵ)  

Determination of chromium(Ⅵ) in soil by flame atomic absorption spectrometry with constant temperature shaking extraction

作　　者：杨建博 孟建卫 邱红绪 刘显 李晓敬 姚然 YANG Jianbo;MENG Jianwei;QIU Hongxu;LIU Xian;LI Xiaojing;YAO Ran(Hebei Research Center for Geoanalysis,Baoding 071001,China;Hebei Key Laboratory of Mineral Resources and Ecological Environment Monitoring,Baoding 071001,China)

机构地区：[1]河北省地质实验测试中心,河北保定071001 [2]河北省矿产资源与生态环境监测重点实验室,河北保定071001

出　　处：《冶金分析》2022年第4期45-52,共8页Metallurgical Analysis

摘　　要：Cr(Ⅵ)量是土壤环境监测的重要指标,Cr(Ⅵ)的浸取和准确测定对土壤污染监测及修复治理至关重要。实验采用Na_(2)CO_(3)-NaOH碱性提取液、磷酸盐缓冲溶液-MgCl_(2)体系于92.5℃恒温水浴振荡的方式浸提土壤中Cr(Ⅵ),在4 000 r/min下离心10 min,用注射器配合针孔滤膜过滤,利用酚酞作指示剂,用50%(体积分数) HNO_(3)调节待测液pH值至7.0~8.0,二次分离Cr(Ⅲ)和Cr(Ⅵ),从而实现了火焰原子吸收光谱法(FAAS)对土壤中Cr(Ⅵ)的测定。在选定的条件下,Cr(Ⅵ)在0.10~2.00μg/mL范围内与其吸收强度呈正比,相关系数为0.999 3;方法检出限为0.43μg/g,定量限为1.51μg/g。在检测过程中,待测液盐分过高、流量的增加会造成盐分在燃烧头快速积聚,从而影响测定结果;试验表明,每测一件样品后用20%HNO_(3)(体积分数)清洗燃烧头5 s的方式可消除该物理干扰。应用实验方法对3种不同含量水平的土壤中六价铬成分分析标准物质GBW(E)070252、GBW(E)070254、GBW(E)070255及4种工业用地土壤样品平行测定12次,标准物质的测定值与认定值基本一致,实际样品测定结果的相对标准偏差(RSD,n=12)均不大于5.6%。按照实验方法测定土壤中六价铬成分分析标准物质并取不同量易溶的K_(2)Cr_(2)O_(7)和难溶的PbCrO_(4)进行加标回收试验,回收率在94%~106%之间。The amount of Cr(Ⅵ) is an important index for the monitoring of soil environment.The leaching and accurate determination of Cr(Ⅵ) content is crucial to the soil pollution monitoring and remediation.Cr(Ⅵ) in soil was extracted with Na_(2)CO_(3)-NaOH alkaline extraction solution,phosphate buffer solution-MgCl_(2) system by shaking in constant temperature water bath shaking at 92.5 ℃.After centrifugation at 4 000 r/min for 10 min,the extracting solution was filtered by syringe combined with pinhole filter membrane.Phenolphthalein was used as the indicator.The pH of testing solution was adjusted to 7.0-8.0 with 50%(volume fraction) HNO_(3) for the secondary separation of Cr(Ⅲ) and Cr(Ⅵ).Consequently,the determination method of Cr(Ⅵ) in soil by flame atomic absorption spectrometry(FAAS) was established.Under the selection conditions,the mass concentration of Cr(Ⅵ) in range of 0.10-2.00 μg/mL was directly proportional to the corresponding absorption intensity.The correlation coefficient was 0.999 3.The limit of detection and limit of quantification was 0.43 μg/g and 1.51 μg/g,respectively.In the detection process,too high salt content in testing solution or the increase of flow rate would cause the rapid accumulation of salt in the combustion head,thus affecting the measurement results.The experimental results showed that the cleaning of combustion head with 20% HNO_(3)(volume fraction) for 5 s after each determination could eliminate such physical interference.Three certified reference materials of soil for composition analysis of chromium(Ⅵ)[GBW(E)070252,GBW(E)070254 and GBW(E)070255] with different content level and four soil samples from industrial land were determined for 12 times according to the experimental method.The determination results of certified reference materials were basically consistent with the certified values.The relative standard deviation(RSD,n=12) of determination results of samples were all not more than 5.6%.The proposed method was applied for the determination of certifi

关 键 词：恒温水浴 振荡 注射器 土壤 铬(Ⅵ) 火焰原子吸收光谱法(FAAS) 

分 类 号：O657.31[理学—分析化学]