激光击穿光谱检测赣南脐橙中铬元素的实验研究

为评估激光诱导击穿光谱技术(LIBS)对水果样品中重金属元素的检测潜力，选用在不同浓度梯度重铬酸钾水溶液中浸泡了30个小时的赣南脐橙样品进行LIBS实验，采集铬元素的特征谱线与峰值强度信息。在激光照射部位称取3 g左右的脐橙样品进行湿法消解，用原子分光光度计检测样品中的铬浓度。实验数据用Origin软件进行拟合后得到了谱线峰值强度和Cr浓度之间的关系曲线，即定标曲线，二者有线性关系，线性相关度0.981 66。由检测限公式计算得到铬浓度的检测限为11.68 μg·g-1。采用该定标曲线即可对赣南脐橙中的铬元素进行定量检测。实验结果表明LIBS技术是一种检测、定量分析水果样品中重金属元素含量的有效手段。

Experimental Study on Chromium in Gannan Navel Orange by Laser-Induced Breakdown Spectroscopy

It is a relatively new task to apply the laser induced breakdown spectroscopy (LIBS) to fruit samples. To apply LIBS technique in the field related to analysis of trace heavy metal element in fruits samples, we have done primary experiments using Gannan navel orange samples. The authors put the samples into different concentration gradient K₂Cr₂O₇ solution and left it for 30 hours, and then we did the LIBS experiment, discriminated characteristic spectra of chromium element and recorded the peak intensity information. Weighing three grams of sample and determined chromium concentration in the samples by atomic absorption spectrophotometer using wet digestion. The calibration curve of the line intensities versus the concentrations of the Cr element was acquired by the Origin software. The authors found that the linear correlation coefficient is 0.981 66. The calibration curve can be used for the quantitative analysis of chromium element with an unknown concentration in Gannan navel orange. The LIBS detection limit of Cr in the solution was 11.64 mg·g-1 from the measured calibration curve. Experiment results showed that LIBS technique is a valid means for measuring and quantitatively analyzing the content of heavy metal elements in fruit samples.