Analytical & Bioanalytical Techniques

Biography

Biography: Istvan Halasz

Abstract

Silica is important component of many heterogeneous catalysts. Catalysis affects ~90% of all chemical products. For elemental analysis by AA or ICP these silica-based catalysts are dissolved by HF and other acids. HF is exceptionally dangerous because of its ability to diffuse through the skin where the fluoride ion binds calcium with subsequent disruption of electrical activity. Therefore, it is desirable to minimize its use to reduce risk and eliminate a lengthy and tedious dissolution process. We speculated that coupling laser ablation (LA) to an ICP-MS could fulfill this desire. However, LA cannot be used for powder samples and LA-ICP-MS is known to be much less accurate than liquid phase measurements, owing to inhomogeneous ablated particle size and inadequate analysis parameters. Here, we report the development of a LA-ICP-MS method for accurately analyzing powdered silica supported catalysts. We melt the powders with a mixture of Li2B4O7 - LiBO2 into a homogeneous solid bead, vaporize the surface with a laser, and then apply a small cyclone before the ICP. Moreover, we optimized the analysis conditions by using statistical experimental design of 11 parameters. Using three commercial zeolite catalysts having Si/Al ratios 2.6, 40, and 140, we show that different parameters significantly affect the accuracy of measuring their Al contents. The relative standard deviation, RSD, remains <5% over the entire concentration range tested, sometimes even <0.5%, which is better than that obtained by the HF dissolution technique.