Uncertainty of the Analytical Values in Laser-induced Plasma Optical Emission Spectrometry for Element-based Sorting of Commercial Aluminum Alloys.

This paper describes uncertainty ranges of the analytical values by laser-induced breakdown spectrometry (LIBS), in order to realize an element-based sorting of commercial Al alloys whose chemical compositions are varied depending on the kind. For this purpose, calibration factors and their standard errors between the emission intensity and the content of major alloyed elements were estimated using a series of standard reference materials of Al alloys. From the result of LIBS analysis, Al alloy samples, labeled as A1050, A1100, A2017, A2024, A5052, A5083, and A6061, were actually classified into the kinds of Al alloy for which the chemical compositions have been standardized by the Japanese Industrial Standards. The sorting was successfully conducted, although several of them could not be classified into a particular alloy type. This was not due to the analytical precision of LIBS but due to a similarity of the chemical composition between several types of the Al alloy. For comparison, a similar sorting procedure was carried out using the analytical result by ICP-OES, which gave the same conclusion as the LIBS. In fact, ICP-OES requires sample pretreatment and dissolution and thus cannot be applied to on-site/in-line analysis, whereas LIBS can provide a rapid response of analytical values. Accordingly, the LIBS analysis may be actually applied for sorting Al alloy materials in detail.