Quantitative Analysis Of Elements Distribution In Shells Based On LIBS

In the cultivation process of scallops, scallops secrete CaCO3to protect themselvesfrom being destructed. Shells are the outer protective layers. Ca is the basic element andthe other trace elements are the isomorphism in the shells. The sorts and the contents ofthe trace elements in the shells can reflect the aquatic environment of the scallops in therange of their wholly lives, so the analysis of trace elements in shells is very significancefor probing the scallops’ aquatic environment. Laser Induced Breakdown Spectroscopy(Laser Induced Breakdown Spectroscopy, LIBS) is based on analyzing the atomic lines orionic lines in the transient plasma for the characterization of samples. LIBS shows a greatadvantages in simultaneous multi-element detection, non-destructive analysis, in-situcapability and without any pretreatment for samples. The potential application of LIBS inthe analysis of shells has an excellent advantage. Hoping to provide reliable data inanalyzing the scallops’ aquatic environment, this thesis is probing the quantitative analysisof elements distribution in shells by LIBS.The thesis begins with a brief background and its significance of this work, a varietyof methods used in elements analysis of shells is shown in chapter1. Chapter2is theoverview of LIBS and the quantitative analysis methods used in LIBS. Then the bulk of theauthor’ contribution, within the general group effort, was to perform the experiments whichare described in Chapters3,4and5.Chapter3begins with the setting up of the experimental platform, describing therelevant instrumentation and the shell samples. The signal detection of the plasma wasunder the experimental platform. Basing the obtained signal, the main and some traceelements of shells are obtained by the analysis of spectral lines respectively. Theexperimental results show that the major elements in shells are Ca, Mg, Sr, Na and so on.Chapter4deals with the measure at the different growth stages of the shell liquidsamples enriched by graphite. Considering the stability of the experiment and the matrix effect, the internal calibration method is chosen for the quantitative analysis. Firstly wedissolve the shells according to the growth stages of the sample and add MnCl2as theinternal standard substance. But the spectra of the trace elements were not detected withhigh efficient spectrograph. The spectroscopy emission characteristics of trace element Srand major element Ca in liquid enriched by graphite is studied by LIBS. The intensities ofSr407.771nm are measured at different concentration of Sr in liquid. The LIBScalibration curve of the analytical spectral was obtained by internal calibration method andthe low concentration quantitative curve R2is0.993. On the basis of the quantitativeanalysis of element Sr and Ca in shells, seven different growth stages liquid samples of theshell were taken as detection targets. The experimental results show that the relativeconcentrations of element Ca in the different growth stages of shells are constant and theelement Ca could be the self-internal calibration element.Based on the advantages of LIBS, the rapid detection of shells is given in Chapter5.The concentration distribution of the ratio between element Sr and element Ca in differentgrowth stages of shells was studied. Comparing with the results of Chapter4, theconcentration distribution of the ratio between element Sr and element Ca has the sametendency when using Mn as the internal calibration element. The concentrationdistribution of the ratio between element Sr and element Ca in four pairs of shells wereanalyzed, contrasting the concentration distribution of the ratio between element Sr andelement Ca, we find that in the wholly lives of the scallops, the regularities of the ratiobetween element Sr and element Ca has the same tendency in the shells in the samecultivating time and they have different growth rate in different cultivating time so theturning points of the concentration distribution of the ratio between element Sr and elementCa are different in different shells who are cultivated in different time.Finally, a summary of the work for the author has done are presented and somesuggests of the possible future development in the analysis of shells.