Two Q-switched Nd:YAG lasers at 1064 nm wavelength have been employed to produce plasmas on aluminum-based alloy in single- and collinear double-pulse laser induced breakdown spectroscopy(LIBS).Time resolved technique was used for detecting emission signal by spectrometer equipped with ICCD detector.The intensity calibration of spectral response was performed by using deuterium and tungsten halogen lamps.Time evolution of the plasma temperature and electron number density was investigated in single- and collinear double-pulse experiments.Based on the investigation of plasma parameters,the emission signal enhancement mechanism was discussed qualitatively.
Astragalus is an important traditional Chinese herb that has therapeutic potential in the treatment of diseases. In this study, the dissolution of metallic elements during the material decoction process was investigated using laser-induced breakdown spectroscopy(LIBS). The Ca, Mg, Al, and Fe in the drug residues, liquid, and vapor were selected for the study of the transfer of elements after different decocting times. It was found that the intensities of the spectral lines for these elements in the drug liquid increased with increasing decocting times.The contrast trend was observed in the residues and only calcium was detected in the vapor.Furthermore, the relative mass concentrations of Ca, Mg, Al, and Fe in the liquid were quantitatively determined by a combination of the standard addition method and calibrationfree-LIBS method by adding the standard concentration solution of Cu and Cd elements into the drug liquids, it can be found that the maximum error between Cd concentration calculated by internal CF-LIBS and the standard is within 10%. This provides a new method of achieving the on-line monitoring and analysis of metallic elements in the production of traditional Chinese medicines.
Laser-induced breakdown spectroscopy(LIBS)has been applied to the analysis of heavy metals in liquid samples.A new approach was presented to lower the limit of detection(LOD)and minimize the sample matrix effects,in which dried wood pellets absorbed the given amounts of Cr standard solutions and then were baked because they have stronger and rapid absorption properties for liquid samples as well as simple elemental compositions.In this work,we have taken a typical heavy metal Cr element as an example,and investigated the spectral feasibility of Cr solutions and dried wood pellets before and after absorbing Cr solutions at the same experimental conditions.The results were demonstrated to successfully produce a superior analytical response for heavy metal elements by using wood pellet as sample matrix according to the obtained LOD of 0.07 ppm for Cr element in solutions.
