摘要
【目的】针对直接使用原子吸收分光光度计石墨炉法测定食用盐中镉含量时存在的氯化钠基体干扰严重(加标回收率仅30%~50%)、检测误差大等问题,文章提出一种基于共沉淀富集镉离子同时降低基体干扰的创新方法。【方法】通过镉离子能在碱性条件下生成氢氧化镉的特性,引入硝酸铁作为共沉淀剂,用氨水调节样品溶液pH值至9.0,使生成的氢氧化镉和氢氧化铁形成稳定的沉淀物,小心吸走含高浓度氯化钠的上清液,酸化溶解沉淀物,用原子吸收分光光度计石墨炉法测定,同时结合电感耦合等离子体质谱仪(ICP-MS)进行方法验证。【结果】改良方法使加标回收率显著提升至104%,相对标准偏差为2.4%,且与ICP-MS测定结果的相对标准偏差仅为0.03%。【结论】该方法通过共沉淀过程消除了样品中氯化钠的干扰,同时实现了镉元素的富集,大大降低了试验的检测下限,提高了测定的精准度。此研究还为高盐基质样品中痕量重金属的精准检测提供了高效解决方案,显著提升了检测灵敏度、准确度和精密度。
[Objective]Addressing the issues of severe matrix interference from sodium chloride(with a recovery rate of only 30%to 50%)and significant detection errors in the direct determination of cadmium content in edible salt using the graphite furnace method of atomic absorption spectrophotometry,this paper proposed an innovative method based on co-precipitation for enriching cadmium ions while reducing matrix interference.[Methods]Leveraging the characteristic that cadmium ions could form cadmium hydroxide under alkaline conditions,iron nitrate was introduced as a co-precipitant.The pH of the sample solution was adjusted to 9.0 with ammonia water,enabling the formation of stable precipitates of cadmium hydroxide and iron hydroxide through co-precipitation.The supernatant containing high concentrations of sodium chloride was carefully aspirated,and the precipitate was acidified and dissolved for determination using the graphite furnace method of atomic absorption spectrophotometry.[Methods]Validation was also conducted using inductively coupled plasma mass spectrometry(ICP-MS).[Results]The improved method significantly increased the recovery rate to 104%,with a relative standard deviation of 2.4%.Furthermore,the relative standard deviation with ICP-MS measurement result was only 0.03%.[Conclusion]This method eliminates the interference from sodium chloride in the sample through the co-precipitation process,while achieving enrichment of cadmium elements,significantly lowering the detection limit of the experiment,and improving the accuracy of determination.This study also provides an efficient solution for the precise detection of trace heavy metals in high-salt matrix samples,significantly enhancing detection sensitivity,accuracy,and precision.
作者
房合书
周民兰
杨帆
丁梅
彭昌龙
黄于富
FANG Heshu;ZHOU Minlan;YANG Fan;DING Mei;PENG Changlong;HUANG Yufu(Guizhou Bijie Water Co.,Ltd.,Bijie 551700,China;Agricultural and Rural Affairs Bureau of Dafang County,Bijie 551600,China)
出处
《净水技术》
2025年第9期196-205,共10页
Water Purification Technology
基金
2024年度无研发活动规上工业企业扶持计划项目:食用盐中镉含量的测定方法改进[黔科统研[2024]344号]。
关键词
食用盐
原子吸收石墨炉法
共沉淀法
镉含量
痕量测定
硝酸铁
edible salt
atomic absorption graphite furnace method
co-precipitation method
cadmium content
trace determination
