Development and characterization of a new laser ablation technique for inductively coupled plasma-atomic emission spectrometry (ICP-AES)

(Uncorrected OCR) Abstract of thesis entitled DEVELOPMENT AND CHARACTERIZATION OF A NEW LASER ABLATION TECHNIQUE FOR INDUCTIVELY COUPLED PLASMA - ATOMIC EMISSION SPECTROMETRY (ICP-AES) submitted by LAM KAR KIN for the degree of Master of Philosophy at The University of Hong Kong in March 1996 A novel laser sampling technique, back surface ablation, has been developed for inductively coupled plasma - atomic emission spectrometry (ICP-AES). Samples are coated onto a transparent substrate and a laser beam is irradiated onto the sample through the substrate instead of sampling directly from a sample surface. As part of the sample is vaporized by the laser beam, high pressure develops at the sample-substrate interface. The sample at the laser spot is explosively and completely removed by the expanding vapor. Sampling efficiency is up to 10 times higher than conventional ’front surface’ laser sampling. Also, stoichiometric sampling is ensured because of complete removal of the sample at the laser spot. The risk of inaccurate chemical analysis associated with non-stoichiometric thermal vaporization in front surface laser sampling is reduced. Two methods of calibration, standard additions and calibration with standards in poly(vinyl alcohol) matrix, were used for quantitative analysis of household paints using front surface and back surface ablation-ICP-AES. Internal standards are used to compensate for pulse-to-pulse laser energy fluctuation and sample thickness variation across a sample. Twelve elements of different thermal properties and concentration ranging from 1 ppm to 2000 ppm were analyzed and the elemental concentration was compared to that of microwave digestion/solution nebulization-ICP-AES. Back surface ablation appears to be more precise and accurate than conventional front surface ablation.

並列關鍵字

Laser ablation. ； Atomic emission spectroscopy.

國際替代計量

主題瀏覽