Nondestructive Determination of Cu Residue in Orange Peel by Laser Induced Breakdown Spectroscopy

Abstract

Laser induced breakdown spectroscopy (LIBS) is an emerging tool with rapid, nondestructive, green characteristics in qualitative or quantitative analyses of composition in materials. But LIBS has its shortcomings in detect limit and sensitivity. In this work, heavy metal Cu in Gannan Navel Orange, which is one of famous fruits from Jiangxi of China, was analyzed. In view of LIBS's limit, it is difficult to determinate heavy metals in natural fruits. In this work, nine orange samples were pretreated in 50-500 µg/mL Cu solution, respectively. Another one orange sample was chosen as a control group without any pollution treatment. Previous researchers observed that the content of heavy metals is much higher in peel than in pulp. So, the content in pulp can be reflected by detecting peel. The real concentrations of Cu in peels were acquired by atomic absorption spectrophotometer (AAS). A calibration model of Cu I 324.7 and Cu I 327.4 was constructed between LIBS intensity and AAS concentration by six samples. The correlation coefficient of the two models is also 0.95. All of the samples were used to verify the accuracy of the model. The results show that the relative error (RE) between predicted and real concentration is less than 6.5%, and Cu I 324.7 line has smaller RE than Cu I 327.4. The analysis demonstrated that different characteristic lines decided different accuracy. The results prove the feasibility of detecting heavy metals in fruits by LIBS. But the results are limited in treated samples. The next work will focus on direct analysis of heavy metals in natural fruits without any pretreatment. This work is helpful to explore the distribution of heavy metals between pulp and peel.

Fast Detection of Copper Content in Rice by Laser-Induced Breakdown Spectroscopy with Uni- and Multivariate Analysis

“…Three kinds of rice commonly found in local supermarkets were used in this experiment, which were Simiao rice (originating from Guangdong, China), Jiangsu rice (originating from Jiangsu, China) and regular rice (originating from Shanghai, China). Samples with different copper contents were prepared in the laboratory with the treatment of a copper (II) sulfate pentahydrate solution [ 36 ].…”

Signal Enhancement of Cadmium in Lettuce Using Laser-Induced Breakdown Spectroscopy Combined with Pyrolysis Process

“…LIBS has been widely used in food quality detection and control, as well as mineral composition analysis and bacteria contamination [13]. LIBS has been investigated by researchers as a rapid, micro-destructive food analysis tool and used in many different food detection areas, such as the Ca content in comminuted poultry meat [14], Cu determination in orange peel [15], Mg determination in wheat flour [16], and mineral composition in milk [17]. As for the Cd analysis in lettuce, we have several results in the previous study, which indicate that LIBS coupled with chemometrics could be used as a fast, efficient and low-cost method to assess Cd contamination in the vegetable industry [18].…”

A Rising Force for the World-Wide Development of Laser-Induced Breakdown Spectroscopy

“…Among these application papers, all the important domains of LIBS application developed in China with a potential large scale market were reported, including coal thermal power plant [15,16] , steel industry or metallurgy [17−22] , construction material production [13] , nuclear industry [23−24] , and environmental [25,26] . Compared with the first thematic issue, in which only the application coal thermal power plant [39,40] , metallurgy [41] , and national security [42] were involved, there were more research topics explored, such as agriculture [27,28] , and under water applications [29] . In addition, among these applications, there were many quantitative applications [8,14,16,17,26,32,35,38] .…”