Tianbing Chen

Detection of heavy metal Cd in polluted fresh leafy vegetables by laser-induced breakdown spectroscopy

In seeking a novel method with the ability of green analysis in monitoring toxic heavy metals residue in fresh leafy vegetables, laser-induced breakdown spectroscopy (LIBS) was applied to prove its capability in performing this work. The spectra of fresh vegetable samples polluted in the lab were collected by optimized LIBS experimental setup, and the reference concentrations of cadmium (Cd) from samples were obtained by conventional atomic absorption spectroscopy after wet digestion. The direct calibration employing intensity of single Cd line and Cd concentration exposed the weakness of this calibration method. Furthermore, the accuracy of linear calibration can be improved a little by triple Cd lines as characteristic variables, especially after the spectra were pretreated. However, it is not enough in predicting Cd in samples. Therefore, partial least-squares regression (PLSR) was utilized to enhance the robustness of quantitative analysis. The results of the PLSR model showed that the prediction accuracy of the Cd target can meet the requirement of determination in food safety. This investigation presented that LIBS is a promising and emerging method in analyzing toxic compositions in agricultural products, especially combined with suitable chemometrics.

Determination of heavy metal chromium in pork by laser-induced breakdown spectroscopy

Meat can be polluted by heavy metals during the feeding of livestock and processing of meat. It is necessary to monitor the concentration of toxic metals in meat. The element chromium (Cr) in pork was selected as a determination target for this work. Fresh pork was polluted in a Cr solution to create a different content level, then dried and pressed into pellets to eliminate the effect of water and improve the stability and sensitivity of laser-induced breakdown spectroscopy (LIBS). The spectra of pressed pellets were collected at optimized LIBS experimental parameters. After that, the real content of samples was obtained by atomic absorption spectroscopy. Characteristic lines Cr I 425.43, Cr I 427.48, and Cr I 428.97 were verified, and a model comparing the LIBS intensity of the line peak and the actual concentration of Cr was constructed. The results showed that the model has better predicted precision and accuracy, especially applying the line Cr I 425.43 for calibration. This work makes it obvious that LIBS has food safety potential for detecting residue of heavy metals in meat.

Analysis the macronutrients in Gannan navel oranges for three kinds of sample state by laser induced breakdown spectroscopy

By detecting the nutrient elements intensity in Gannan navel oranges for analysis the difference among the three states and the reasons, the K, Ca, and Na elements have been analyzed by laser induced breakdown spectroscopy (LIBS) technique, which is made up with a Nd:YAG ns laser at 1064 nm and an eight-channel Ava-Spec spectrometer with CCD detector and optical devices. The absolute and relative intensity of characteristic spectra for K, Ca, Na were obtained that can find out that the powdery orange peel intensity is more than fresh orange peel, and lager than digestion liquid for the same analytical spectra, Also a different intensity for different analytical spectra in the same element and for a diverse element in the same condition, which is due to the moisture content, the state of matter and the compactness. It is also indicated that LIBS technique will be a rapid and effective method for quantitative analysis of nutrient elements in matter by the relative intensity or normalized intensity.

Using laser induced breakdown spectroscopy to analyse the chromium in soil for a different spectrum line

By detecting the chromium (Cr) element intensity in soil for the different analytical spectra lines by laser induced breakdown spectroscopy (LIBS) technique, which is made up with an Nd: YAG ns laser at 1064 nm and a multichannel spectrometer with ICCD detector, DG535, computer and optical devices. And using the obvious quantitative methods that make use of the absolute intensity, the relative intensity and the logarithm of intensity set up linear relation. The results show that the Cr I 425.43nm analytical spectra line and taking the logarithm of intensity are identified as the optimal analytical spectra line and the quantitative methods. It is also indicated that LIBS technique wants to be a rapid and effective method for quantitative analysis still needed to solve a mass of work.

Research of the metal Cr accumulation in plant leaves using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS), an emerging technique for materials quantitative analysis, is rapidly maturing and is becoming increasingly accepted as an important tool for the metal detection. In this paper, a LIBS system with a 10 Hz Q-switched Nd: YAG ns laser at 1064 nm was employed to research the metal element Cr in plant leaves. Refer to NIST atomic database, the metal element Cr is identified in the soaked sample. According to statistical methods and spectrum analysis software, the calibration curve of the metal element Cr was obtained in our laboratory. The correlation coefficient of calibration curve is 0.97394 for Cr 425.43 nm and 0.94005 for Cr 427.48 nm respectively. The experimental results show LIBS technique is a fast and effective tool for detecting and analyzing the relative intensity of the metal elements and provides the basis of the rapid and continuous detection for plant metal.