Effect of the chemical form of the additives in poly(vinyl chloride) and poly(ethylene) materials on laser ablation efficiency using inductively coupled plasma atomic emission spectrometry

The application of Laser Ablation Inductively Coupled Plasma Atomic Emission Spectrometry to the direct determination of additives in polymeric materials has been studied. A Nd:YAG laser, operating at both infrared (1064 nm) and UV (266 nm) wavelengths, has been used with a beam masking and a beam expander device for solid sampling of poly(vinyl chloride) (PVC) and poly(ethylene) (PE) materials. Emphasis was placed on the influence of the chemical structure of the elements to be determined and of the polymer matrix on laser ablation efficiency. Several samples of PVC and PE were produced by compounding Ca-, Sn- and Ti-based additives in the basic resins. In both polymers, the three elements were incorporated either as inorganic compounds, as organometallic compounds, or as a mixture of the two former structures. It has been shown that the signal-to-concentration ratios of the elements studied were strongly dependent on (i) the chemical structure of the elements in the additives used, (ii) the nature of the polymer matrix, and (iii) the interactions between additives, and between additives and the polymer. The carbon line was not sufficiently efficient to compensate for these effects, and the modification of the laser operating parameters did not affect significantly the ablation process. The results presented in this work pointed out the need to match matrix samples and standards to achieve reliable quantitative analysis of polymers. (C) 1997 Elsevier Science B.V.