水田污染区稻壳与糙米中铬元素的LIBS分析可行性

为验证激光诱导击穿光谱(LIBS)对江西省环鄱阳湖水田污染区稻谷中铬元素的分析可行性，本试验以在该区收集的稻壳、糙米和白米作为研究对象，分别对所有样品进行LIBS测试，并利用火焰原子吸收法(AAS)对铬元素进行真实浓度检测。LIBS图谱显示稻壳中明显地检测到了铬元素的特征谱线，而糙米和白米则检测不到。AAS结果显示稻壳中Cr浓度远高于糙米，而白米中Cr未超标，同时，稻壳与糙米Cr浓度比率具有一定的梯度关系。结果说明，Cr在稻壳中的富集量高于糙米和白米，利用LIBS技术对稻壳中Cr进行检测具有一定的可行性，最终有望实现通过采集稻壳LIBS光谱信号，预测出糙米中重金属元素的分布规律，进而采用类似的方法获取大米中重金属元素含量。

Feasibility of Analyzing Cr in Rice Husk and Coarse Rice with LIBS

To validate the feasibility of laser induced breakdown spectroscopy (LIBS)in detecting Cr in rice of polluted areas of Poyang Lake in Jiangxi province,rice husk samples,coarse rice samples and polished rice samples in the area were selected ran-domly as targets.In this work,these samples were tested with LIBS and the content of Cr was acquired by flame atomic absorp-tion (AAS)in fresh samples.LIBS spectra showed that Cr Ⅰ 425.43 nm,Cr Ⅰ 427.48 nm,Cr Ⅰ 428.97 nm and abundant mineral elements such as Fe and Si were detected clearly ,but they were undetectable directly in coarse rice and polished rice. The results of AAS shows that Cr in rice husk is more than the corresponding coarse rice and the Cr in polished rice does not ex-ceed the limited content of 1 mg·kg-1 according to qualified national standards GB 2762—2012.The ratio between rice husk and coarse rice is about 78.95,it displayed the distribution is clear.This shows that compared with coarse rice,the concentra-tion enrichment ratio of Cr in rice husk is higher than the coarse rice.The results demonstrate that it is feasible to detect Cr in rice husk and coarse rice.Therefore,it is helpful to predict the distribution of heavy metals in agricultural products by means of green method without pollution.