Applications of Laser Microprobe Mass Spectrometry in Biology and Medicine

Laser microprobe mass spectrometry (LMMS) provides spot analysis with a lateral resolution of 1-5 μm. Focused laser ionisation, combined with mass spectrometry, yields information on elements, molecular identification of inorganic substances, and structural characterisation of organic molecules of typically less than 2-3 kDa. Quantification in complex heterogeneous systems, such as biological materials, is not possible at the present state of the art. The strength of the method lies in the qualitative information on the molecular composition of the analyte, not just element detection, with a lateral resolution at the light microscopy level. The applications of this technique in the field of biomedicine and biology are illustrated by examples that demonstrate the use of this qualitative information in practical test cases

In Situ Temperature-Time Effect on MetA-S-SIMS

Metal-assisted (MetA) static secondary ion mass spectrometry (S-SIMS) is one of several ion yield enhancing methods developed for S-SIMS in the last decades. MetA-S-SIMS uses a very thin coating of gold or silver on the sample. Earlier experiments revealed dependence of the ion yield enhancement on the applied metal, the nature of the studied sample, the time after metallization, and the heating temperature (ex situ, i.e., under atmospheric pressure). This paper reports on the effects of time and temperature when samples are heated to temperatures between 30 and 80°C inside the S-SIMS vacuum chamber (in situ). Thick layers of poly(vinylbutyral-co-vinylalcohol-co-vinylacetate) (PVB) containing dihydroxybenzophenone (DHBPh) were coated with a nm-thin-layer of gold. The S-SIMS analysis was performed over a period of several hours while samples were kept at a constant elevated temperature. Compared to ex situ heating in an oven, heating in the analysis chamber provided more rapid signal enhancement, but the magnitude of the enhancement was less (by a factor of two). Furthermore, additional experiments on ex situ heated samples revealed that storage of samples with enhanced ion yields at −8°C is not sufficient to “stabilize” the enhancement. A steep decrease of the ion yields was observed as a function of time after 2.5 h

Laser Microprobe Mass Spectrometry in Biology and Biomedicine

An overview is given of laser microprobe mass spectrometry (LMMS) in biology and biomedicine (1989-1993). The present instrumentation and its analytical features are surveyed. Applications are presented with special attention on human and animal tissue samples, as well as plant material. The capabilities of LMMS to study the element distribution in histological sections, to identify the chemical composition of inorganic inclusions and to generate structural information from organic compounds are evidenced