Trace analysis microelectrodes

Volumetric Absorption Cells. Often the amount of sample available for trace analysis is rather limited also, it is often desirable to make the final volume as small as possible, so that absorbance is maximized. This may be accomplished by calibrating an absorption cell to a definite volume by putting a mark on the side and using it as a volumetric flask. Color development may be carried out in the cell, in order to keep the final volume at a minimum. If pH adjustment is required, a glass microelectrode may be used. For an ordinary 1-cm cell, volumes of about 3 ml may be used. 

E. Gileadi (Tel Aviv University, Israel) The use of ensembles of microelectrodes for trace analysis should be considered. Recent studies in our laboratory (H. Reller, E. Kirowa-Eisner and E. Gileadi, J.Electroanal. 

Hanging mercury drop electrode (HMDE) A microelectrode that can concentrate traces of metals by electrolysis into a small volume the analysis is completed by voltammetric stripping of the metal from the mercury drop. 

Strips of tissue from the SA nodal region of rabbit heart are dissected and immersed in Tyrode solution at 35°C. By subsequent cuts and ligatures a strip is reduced to a 0.25 x 0.25 mm beating preparation, which is impaled with two standard 3M KCl microelectrodes (about 40 Mohms). Voltage clamp is performed with traditional methods Voltage and current traces are recorded on a two-trace storage oscilloscope and on a 4 FM channel tape recorder for subsequent analysis... 

Electrochemical sensing of chemical species with high oxidation potentials and trace metal analysis are major apphcations for both microelectrodes and BDD electrodes. These electrodes are also expected to exhibit high stability, similar to their planar counterparts [9], Further work on electroanalysis using BDD MDAs is in progress in our laboratory. 

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