Mass spectroscopy tissue analysis

Nixon277 compared atomic absorption spectroscopy, flame photometry, mass spectroscopy, and neutron activation analysis as methods for the determination of some 21 trace elements (<100 ppm) in hard dental tissue and dental plaque silver, aluminum, arsenic, gold, barium, chromium, copper, fluoride, iron, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, tin, strontium, vanadium, and zinc. Brunelle 278) also described procedures for the determination of about 20 elements in soil using a combination of atomic absorption spectroscopy and neutron activation analysis. 

Numerous procedures, by a variety of different instruments, are available to quantify the amount of thallium present in hair, blood, tissue, saliva, and urine (for reviews, see [9,81]). Instrumentation used includes emission spectrography, flame and flameless atomic absorption spectroscopy (AAS), voltammetry, neutron activation analysis, and field desorption mass spectroscopy [13,17,82-90]. Field desorption mass spectroscopy when combined with stable isotope dilution can detect fentomole quantities and has value in that no tissue preparation (other than homogenization) is required [65,82,89], The use of these two methods, however, is restricted to specialized laboratories. 

General and Selective Isolation Procedure for Gas Chromatography/Mass Spectroscopy Analysis of Steroids in Tissues and Body Fluids... 

Figure 2 The two most frequently used approaches for metabolomics are NMR spectroscopy and mass spectrometry. To maximize the coverage of the metabolome, these techniques can be combined. This figure shows the analysis of the aqueous fraction of a section of heart tissue that uses NMR spectroscopy, gas chromatography mass spectrometry and liquid chromatography mass spectrometry. Although mass spectrometry approaches are inherently more sensitive than NMR spectroscopy, metabolite identification becomes more difficult.

Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) is used for multi-element determinations in blood and tissue samples. Detection in urine samples requires extraction of the metals with a polydithiocarbamate resin prior to digestion and analysis (NIOSH 1984a). Other satisfactory analytical methods include direct current plasma emission spectroscopy and determination by AAS, and inductively coupled argon plasma spectroscopy-mass spectrometry (ICP-MS) (Patterson et al. 1992 Shaw et al. 1982). Flow injection analysis (FIA) has been used to determine very low levels of zinc in muscle tissue. This method provides very high sensitivity, low detection limits (3 ng/mL), good precision, and high selectivity at trace levels (Fernandez et al. 1992b). 

Optical microscopy (OM), polarized light microscopy (PLM), phase contrast microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) are the methods normally used for identification and quantification of the trace amounts of asbestos fibers that are encountered in the environment and lung tissue. Energy-dispersive X-ray spectrometry (EDXS) is used in both SEM and TEM for chemical analysis of individual particles, while selected-area electron diffraction (SAED) pattern analysis in TEM can provide details of the cell unit of individual particles of mass down to 10 g. It helps to differentiate between antigorite and chrysotile. Secondary ion mass spectrometry, laser microprobe mass spectrometry (EMMS), electron probe X-ray microanalysis (EPXMA), and X-ray photoelectron spectroscopy (XPS) are also analytical techniques used for asbestos chemical characterization. 

It can be seen from these examples that cells and tissues are very sensitive to the composition of the materials surface. Several physicochemical techniques for analysing the composition of materials surface have been described. However, attention is drawn to the fact that the surface analysed by most of these methods is not the surface analysed by living cells, as cells recognise only the outermost layer of a hydrated material. Analysing this ultimate hydrated layer by a physicochemical method is a real challenge. Indeed, the most surface-sensitive methods such as electron spectroscopy for chemical analysis (ESCA also known as X-ray photoelectron spectroscopy, XPS) and secondary-ion mass spectrometry (SIMS) can analyse respectively a few layers at once or one layer after the other, but in strictly dry conditions. Performing an ESCA analysis at a very low temperature in order to keep water frozen has been described, but this is currently far from a routine method. Conversely, analysis of hydrated surfaces by ATR-IR is usual, but this method determines the composition of many layers in addition to the ultimate layer, as it analyses a depth of more than 1 pm. 

There are three techniques used for the determination of chromium in tissues and body fluids (1) neutron activation analysis (NAA), (2) isotope dilution mass spectrometry (IDMS), and (3) electrothermal atomic absorption spectroscopy (ETAAS). 

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