ABSTRACT
Laser-induced breakdown spectroscopy (LIBS) is a sensitive optical technique that is capable of rapid multi-elemental analysis. The development of this technique for elemental analysis of pharmaceutical products may eventually revolutionize the field of human health. Under normal circumstances, the elemental analysis of pharmaceutical products based on chemical methods is time-consuming and complicated. In this investigation, the principal aim is to develop an LIBS-based methodology for ele-mental analysis of pharmaceutical products. This LIBS technique was utilized for qualitative as well as quantitative analysis of the elements present in Ca-based tablets. All the elements present in the tablets were detected and their percentage compositions were verified in a single shot, using the proposed instrument. These elements (e.g., Ca, Mg, Fe, Zn, and others) were identified by the wavelengths of their spectral lines, which were verified using the NIST database. The approximate amount of each element was determined based on their observed peaks and the result was in exact agreement with the content specification. The determination of the composition of prescription drug for patients is highly important in numerous circumstances. For example, the exploitation of LIBS may facilitate elemental decomposition of medicines to determine the accuracy of the stated composition information. Moreover, the approach can provide element-specific, meaningful, and accurate information related to pharmaceutical products.
ABSTRACT
Laser induced breakdown spectroscopy ( LIBS ) was proposed to rapidly discriminate microbe species. Ten species of microbes were prepared in lab. Filter papers were selected as substrate for enriching bacteria and enhancing the quality of LIBS. The images of plasma were collected by ICCD camera and LIBS spectra were obtained by spectrometers. The results displayed that the images and spectra were different from 10 bacteria. It was demonstrated that this method was feasible to discriminate bacteria species by analyzing image and/or spectroscopy. Furthermore, nine smooth and multiple scattering correction ( MSC) were utilized to preprocess the LIBS full-spectrum data in the wavelength range of 200-420 nm and 560-680 nm. And principal component analysis ( PCA) and PCA-RF ( Random forest) were compared to validate the accuracy of discrimination. The investigation showed that the PCA-RF model coupled with suitable methods in preprocessing data could identify bacteria. The accuracy was 99. 6% for ten species of microbes by evaluating LIBS spectra in training set, and 96. 7% in predicting set. This report indicated that it is feasible to differentiate bacteria species by analyzing LIBS spectra.
ABSTRACT
Laser-induced breakdown spectroscopy (LIBS) was used for analysis of the distribution of S,Mn,Fe,Cr,Mo,Si,Al in a 34CrNiMo6 steel sample cut from a main shaft of wind driven generator.The MnS inclusion area in each ablation craters cover zone was extracted in the way of comparing the metallograph captured by optical microscopy before and after LIBS scanning ablation.The statistic relation between MnS inclusion area and signal intensity of S and Mn was analyzed.The result showed that the abnormal signal of S and Mn occurred at the same position with the existence of MnS inclusion,and their signal intensity showed linear relationship.The abnormal signal of S and Mn were triggered mainly by MnS inclusion.The statistic result also showed linear relationship between signal intensity and MnS inclusion area both for S and Mn.It was possible to determine the inclusion type,size and distribution by analyzing abnormal signal.A simplified ablation model was established to calculate the relation of S and Mn content to MnS inclusion area.The arithmetic result showed a linear relation between the content and MnS inclusion area both for S and Mn.The calculation confirmed the linear relationship between signal intensity and inclusion area observed in experiment.The linear relationship could be interfered by macro-segregation,micro-segregation,deviation in measuring inclusion area,and inclusion spatter in pre-ablation.
ABSTRACT
There are many noise signals in original laser induced breakdown spectroscopy (LIBS) spectra.To explore the effect of spectral pretreatment on LIBS information by different filter methods, the LIBS spectra of Pb-polluted cabbage in wavelength range of 400.45-410.98 nm was investigated and preprocessed by adjacent averaging, Savitzky-Golay (S-G) and fast Fourier transformation (FFT).Then partial least square (PLS) model was established for evaluating the spectral treatment effect.The result showed that the root mean square error of prediction (RMSEP) and average relative error of S-G method were 0.26 and 3.7%, suggesting a superior smoothing effect than other methods.Experimental results indicated that an appropriate filtering method could help to improve the spectral quality and raise the precision of model checkout.
ABSTRACT
Laser-induced breakdown spectroscopy has become a very attractive technique in the field of chemical analysis.The technique utilizes a laser focused on a small spot to create a micro-plasma on the sample surface.In recent years, laser-induced breakdown spectroscopy (LIBS) is a frontier analysis technique in spectrometric analysis, with the advantages such as real-time, online and non-contact analysis.The research and development of various instruments based on this technology has attracted great attention of researchers.In the article, we reviewed the research progress of LIBS instrument from the components and field equipment in recent years, mainly including portable LIBS, handheld LIBS and remote LIBS.
ABSTRACT
Heavy metal residue in vegetables is a big concern in the whole world.The aim of this work is to explore the effect of multivariable selection on analyzing Cd in Chinese cabbage polluted in lab by collecting the spectra of laser induced breakdown spectroscopy (LIBS) from the samples.At the same time,the actual Cd content in samples was obtained by anodic stripping voltammetry (ASV).The LIBS spectral range in partial least square (PLS) model was screened by standard normal variable transformation (SNV),first derivative (FD),second derivative (SD) and center treatment (CT) for preprocessing spectra and the optimized method was used for the analysis of interval partial least square (iPLS) and synergy interval partial least square (SiPLS).The results indicated that the method of CT was the best as a comparison with PLS,iPLS and SiPLS.And the intervals of wavelength were 214.72-215.82 nm,215.88-216.97 nm and 225.08 -226.35 nm by utilizing the optimized SiPLS.Here the root mean square error of cross validation (RMSECV) between real content and predicted ones was 1.487,the root mean squared error of prediction (RMSEP) was 1.094,the correlation coefficient (R) was 0.9942,and the average relative error (ARE) was 11.60％.The results displayed that LIBS could predict Cd in vegetables by multivariable selection of SiPLS and the accuracy could meet the requirement of rapid and green analysis of Cd in vegetables.
ABSTRACT
The blending end-point determination of Angong Niuhuang Wan (AGNH) is a key technology problem. The control strategy based on quality by design (QbD) concept proposes a whole blending end-point determination method, and provides a methodology for blending the Chinese materia medica containing mineral substances. Based on QbD concept, the laser induced breakdown spectroscopy (LIBS) was used to assess the cinnabar, realgar and pearl powder blending of AGNH in a pilot-scale experiment, especially the whole blending end-point in this study. The blending variability of three mineral medicines including cinnabar, realgar and pearl powder, was measured by moving window relative standard deviation (MWRSD) based on LIBS. The time profiles of realgar and pearl powder did not produce consistent results completely, but all of them reached even blending at the last blending stage, so that the whole proposal blending end point was determined. LIBS is a promising Process Analytical Technology (PAT) for process control. Unlike other elemental determination technologies such ICP-OES, LIBS does not need an elaborate digestion procedure, which is a promising and rapid technique to understand the blending process of Chinese materia medica (CMM) containing cinnabar, realgar and other mineral traditional Chinese medicine. This study proposed a novel method for the research of large varieties of traditional Chinese medicines..
ABSTRACT
Laser-induced breakdown spectroscopy ( LIBS) was used to detect the compositions of soil in the air, and the quantitative analysis model with genetic algorithm-partial least squares ( GA-PLS ) was established. A total of fifty-eight soil samples were split into calibration, monitoring and prediction sets. Eleven soil compositions including Mn, Cr, Cu, Pb, Ba, Al2 O3 , CaO, Fe2 O3 , MgO, Na2 O, and K2 O were quantitatively analyzed. The results demonstrated that, as a pretreatment method for optimizing the selection of spectral lines, GA could be effectively used to reduce the number of spectral lines for use in building PLS model, and hence simplify the quantitative analysis model. More importantly, for most of the soil compositions, GA-PLS could significantly improve the prediction ability compared with the conventional PLS model. Take Mn as an example, the root-mean-square error of prediction ( RMSEP ) was decreased from 0. 0215% to 0 . 0167%, and the mean percent prediction error ( MPE ) was decreased from 8 . 10% to 5 . 20%. The research provides an approach for further improving the accuracy of LIBS quantitative analysis in soil.
ABSTRACT
Laser-induced breakdown spectroscopy (LIBS) was applied to perform qualitative research on Tibetan medicine “GTso Thal” in order to establish a rapid element analysis method . The Nd: YAG laser with the funda-mental frequency at 1064 nm was used. A high-power laser beam was focused on the surface of the sample. The spectrometer and CCD was used to detect its spectrum signals. Based on the National Institute of Standards and Technology (NIST) database, emission spectrum characteristics were differentiated. The LIBS spectra of “GTso Thal”showed multi-elements including Hg, Ca, Na, As, Fe, Mg, Al, K, Li, Pb, Ag, Au and S. Among them, Hg, Pb, Ag and Au were heavy mental elements. The results demonstrated that LIBS was a viable technique for analysis of Ti-betan medicine “GTso Thal”. LIBS provided reliable elemental analysis on Tibetan medicine “GTso Thal”. The de-tection was real-time, rapid and in situ. It had prospects in the elemental analysis of ethnic medicine study. LIBS had broad application prospects.
ABSTRACT
ScanningElectronMicroscopy/EnergyDispersionSpectrum(SEM/EDS),ElectronProbe Microanalysis ( EPMA ) and Optical Microscopy ( OM ) are the traditional methods for inclusion type identifying at present. The disadvantages such as inconvenient sample preprocessing, low sensitivity and time consuming limited their application. Laser-Induced Breakdown Spectroscopy ( LIBS) is not only performing in bulk analysis field but also in elemental distribution and depth profile information field, so it causes great concern in material science. In this paper, 34CrNiMo6 steel and heavy railway steel samples were analyzed by LIBS in scanning mode to characterize the inclusion type. For 34CrNiMo6 steel, 2D intensity distribution and channel combination revealed the spectra line intensity of Mn and S were abnormal high simultaneously at some region, which indicated there were some MnS inclusion existed in these samples. And for heavy railway steel, 2D distribution and channel combination revealed the spectra line intensity of Si, Ca, Mg and Al were abnormal high simultaneously at some region, showed the existence of Si-Al-Ca-Mg inclusion in these samples. The SEM/EDS analysis result of above-mentioned samples showed agreed well with LIBS.