Herbert Struyf

DESORPTION/IONIZATION OF INORGANIC COMPOUNDS IN FOURIER TRANSFORM LASER MICROPROBE MASS SPECTROMETRY WITH EXTERNAL ION SOURCE

Application of FT LMMS to inorganic compounds offers the advantage of direct speciation. This means that signals which refer to intact analyte molecules are detected. Current concepts of desorption and ionization in LMMS are mainly based on time-of-flight data and hence on ions formed during the laser pulse. This paper focuses on indications about the desorption and ionization mechanisms for inorganic compounds that can be deduced from the mass spectra in our FT LMMS database. Specifically, the occurrence of continuing ion formation during several hundreds of microseconds is demonstrated. These data are relevant to the possible role of selvedge ionization versus direct ion emission from the solid state.

Laser microprobe Fourier transform mass spectrometer with external ion source for organic and inorganic microanalysis

Abstract The earlier laser microprobe (LM) mass spectrometer with a time-of-flight (TOF) analyser showed that the irradiation of solids by a focused UV laser represents and interesting means of performing local analysis. However, the subsequent measurement of the generated ions is done under low-resolution conditions. The characterization of heterogenous samples and the occurence of poorly understood ion formation mechanisms motivated the development of an instrument with superior mass spectrometric performance. Specifically, Fourier transform (FT) mass spectrometry potentially provides the required high mass resolution and accurate mass determination in combination with adequate sensitivity. In this work an FT-LM mass spectrometer with an external source was developed. Analysis is performed in the reflection mode with a 5-μm spot from a Q-switched Nd:YAG laser. Transfer of ions from the external source into the cell is performed by static electrical fields. The resulting mass separation imposes limitations on the panoramic spectrum registration in the case of pulsed laser microbeam ionization of solids, producing ion bunches over not more than a few hundred microseconds. This paper addresses instrument design and performance with respect to sensitivity, spatial resolution and accuracy of m/z determination and the problem of panoramic registration. Attention is focused on the comparison of results from FT- and TOF-LM mass spectrometry in relation to the determination of the speciation of inorganic compounds and diagnostic analysis of organic molecules.

An overview of wet deposition of micropollutants to the North Sea

Abstract An overview of the wet deposition of micropollutants (trace metals—Cd, Cr, Cu, Pb, Hg, Zn— and organic compounds—PAHs, PCBs, pesticides) to the North Sea and adjacent areas is presented. The results of (in)direct measurements of the wet flux are compared to modelling results. Attention is given to specific problems like revolatilization, sea-spray, contamination, gas-to-particle ratios in wet deposition of Hg and the organic substances. Also, the importance of wet deposition is weighted to that of dry deposition and non-atmospheric input routes to the North Sea. It is concluded that—especially for organic micropollutants—current knowledge is insufficient to yield an accurate and detailed image of the impact and importance of wet deposition to the North Sea.

Feasibility of Fourier transform laser microprobe mass spectrometry for the analysis of lubricating emulsions on rolled aluminium

Additives from lubricating emulsions used in the rolling step of aluminium plate production, are suspected to adhere to the surface and change the surface properties of the metal. The present study aims at investigating the feasibility of a Fourier transform laser microprobe mass spectrometer with external ion source to characterize the organic components at the metal surface. Special attention is given to the possible interactions between the additives and the aluminium. The experiments primarily involve model systems, consisting of aluminium with a thin coating of the individual components or of laboratory-made mixtures.

Assessment of local analysis by fourier transform laser microprobe mass spectrometry with external ion source

Laser microprobe mass spectrometry (LMMS) is a technique for local analysis of inorganic and organic constituents in the μm range. This paper will focus on selected applications. First of all, element detection is illustrated by data from a 50-nm TiW layer on silicon and by the detection of residual Cr on HPLC column packing material. Speciation capabilities of LMMS are demonstrated on pure substances and on a coated neo-ceramic. Finally, the feasibility of organic analysis is shown in the case of a biologically active compound and dyed cloth fibres.