Microchemical analysis on thin sections of soils with the laser microprobe mass analyser (LAMMA)

Summary Experiments with a LAMMA-500 instrument were performed in order to test whether or not thin sections of soils with a thickness of more than 15 m could be analysed with this instrument. Although the usual thickness of the specimens for this instrument lies between 0.1–1 m, it was possible to analyse such thick sections by application of laser milling in which the laser beam was aimed at grazing incidence onto the edge of the section. In this way a path was cleared through the section by erosion and the material that sputtered away along this path could be analysed.

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Mikrochemische Analyse an Dünnschliffen von Bodenproben mit Hilfe von LAMMA

     

LAMMA analysis of organo-metallic compounds

Summary LAMMA spectrometry allows to study many kinds of insoluble and non volatile organometallic compounds. The mass peak of the positive part of such molecules can be seen in positive LAMMA spectra. It is possible at times to quickly verify the coordinance degree of metal. At last, by LAMMA spectrometry, it is even possible to describe some very intricate systems such as asphaltenes.

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LAMMA-Analyse von organo-metallischen Verbindungen

     

Preparation and analysis of heart and skeletal muscle specimens with LAMMA

Summary A technique is described to obtain shockfrozen tissue specimens from a beating heart in situ using liquid propane as cooling agent. The method allows to take up to 8 samples from the ischemic area of the left ventricle of a pig heart following acute coronary artery occlusion.A freeze-drying apparatus was developed in which, under a vacuum of 10^–6 mm Hg, the specimens remain for 10 days with the temperature slowly rising from initially –100 C to room temperature. Freezing damages in the tissues samples due to the formation of ice crystals either during shock-freezing or freeze-drying are usually below the spatial resolution of the microscope system employed in the LAMMA instrument. Already after a few minutes of ischemia, a considerable decrease of the intracellular K/Na relation was measured. LAMMA spectra from skeletal muscle were taken to check for possible ion redistribution which had eventually occurred during the various steps of the preparation procedure employed.Supported by Deutsche Forschungsgemeinschaft, SFB 68, A 10     

Quantitative LAMMA analysis of biological specimens I. Standards. II. Isotope labeling

Summary Besides a remarkably high sensitivity for light elements, laser microprobe mass spectroscopy offers two main advantages for microprobe analysis: 1) the possibility to obtain data of relatively high precision and 2) the ability to discriminate isotopes. This opens the possibility to use cold isotopes as atomic labels to study cellular or subcellular kinetics of ions or labelled organic compounds. In this study photoreceptor cells were labelled with ⁴⁴Ca²⁺ prior to LAMMA analysis to monitor Ca²⁺ uptake and/or Ca²⁺ accumulation from extracellular sources into intracellular compartments such as the various pigment granula present in these photoreceptors.As in other microprobe techniques also LAMMA analysis requires internal standards for quantitative work. For this purpose thin films of inorganic material were shown to be useful standards when deposited (in vacuum) directly onto the specimen to be analyzed. Some metals and dielectrica have been tested for their possible suitability for standardisation procedures. Even though metals like Pt, Ag, Au, Al are excellent for thin film production, they seem to be less useful for the present purpose because their threshold for laser induced perforation and ion production is rather different from that of the specimen material. However, thin film deposits of some dielectric materials such as MgF₂ turned out to be more suitable to serve as an internal standard for plastic embedded biological material in LAMMA analysis.

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Quantitative LAMMA-Analyse biologischer Proben. I. Standards. II. Isotopenmarkierung

     

Studies concerning the distribution of inorganic wood preservatives in cell wall layers based on LAMMA

Summary The Laser Microprobe Mass Analyzer (LAMMA) proved to be a useful instrument for element localization in single wood cells treated with preservatives. The relative concentration of elements occurring within the cell wall can also be determined. Even those with low mass numbers, namely boron and fluorine, are identifiable. In this respect, LAMMA-analysis is preferable to electron probe X-ray microanalysis.Poles treated with CCF- or CCB-preservatives exhibit an overall gradient of ion concentration across the sapwood. Chromium becomes more strongly fixed in the wall than copper. Relative to these elements boron becomes rather irregulary distributed. Moreover, the adsorption of fluorine is considerably low.

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Untersuchungen über die Verteilung anorganischer Holzschutzmittel in Zellwandschichten mit Hilfe von LAMMA

     

Mass spectrometry of molecular solids

Summary Positive and negative ion spectra of various industrially important polymers were recorded using the Laser Microprobe Mass Analysis (LAMMA) technique. Using methods developed in earlier work [1] we interpret the ions as being generated from the polymer backbone or pendant sidechain functional groups. Results are given for polypropylene, polyacrylamide, polystyrene, polycaprolactam (Nylon 6) and polydimethylsiloxane. Mass patterns are analyzed and compared to the previous work.Part I: see [1]     

Localization of lead in cells of Phymatodocis nordstedtiana (Chlorophyta) with the laser microprobe analyzer (LAMMA 500)

Summary Laser microprobe mass analysis (LAMMA) was used to localize lead deposited in cells of Phymatodocis nordstedtiana. Lead contaminated cells were obtained by incubation in an experimental medium containing 1 mg of lead per litre. By means of LAMMA analysis lead deposits were demonstrated in the chloroplast and pyrenoid, in the nucleus and in the cell wall. Lead content of the cytoplasm was generally low. The results are compared with analyses by energy dispersive X-ray microanalysis (EDX).This work has been supported by the Deutsche Forschungsgemeinschaft (grant Lo 216/6). We would like to thank Miss Manshard and Miss Wachholz for their expert help in sample preparation and Dr. H. J. Heinen of Leybold-Heraeus for his help with LAMMA analysis     

Cation distribution of the cochlea wall (Stria vascularis)

Summary It was possible to maintain the differentiated structure of inner ear tissues by freezing in supercooled propane, freeze-drying under special conditions and embedding the tissue in a low viscosity resin. Using LAMMA we were able to measure intracellular ion concentration and concentration gradients in the soft tissues such as muscle and stria vascularis specimens. The preliminary results demonstrate that the distribution of cations in the lateral wall of the cochlear duct is not uniform. The K/Na ratio in the basal cells was significantly higher (121) than in the spiral ligament and middle part of the stria vascularis (71). Changes of such concentration ratios recorded after anoxia suggest that an energy dependent active transport mechanism must exist in the stria vascularis.

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Kationenverteilung in der Schneckengangwand des Ohres (Stria vascularis)