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The 1976 Mars Viking Landers performed a series of experiments in which soil samples were analyzed for evidence of life. Biological responses were not detected; however, the soil samples from [...], The Viking Landers were unable to detect evidence of life on Mars but, instead, found a chemically reactive soil capable of decomposing organic molecules. This reactivity was attributed to the presence of one or more as-yet-unidentified inorganic superoxides or peroxides in the martian soil Using electron paramagnetic resonance spectroscopy, we show that superoxide radical ions ([MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]) form directly on Mars-analog mineral surfaces exposed to ultraviolet radiation under a simulated martian atmosphere. These oxygen radicals can explain the reactive nature of the soil and the apparent absence of organic material at the martian surface.

Electrodes constructed from single-crystal sections of rare earth fluorides respond to fluoride ion activity over more than five orders of magnitude and show a high selectivity for fluoride over other common anions. These electrodes can be used for either direct measuremnent of fluoride ion activity or detection of the end point in titration.

A new potassium electrode, made from valinomycin, which uses commercially available electrode configurations, responds to potassium ion concentrations from 1 mole per liter to below 10(-6) mole per liter. It is highly selective for potassium ion over sodium ion and divalent ions and can be used for the direct determination of potassium ion in human serumn. No significant complexing of potassiium appears to occur in normal seruin.

Organic amines, present in very small concentrations (below 10(-6) M) in 0.1N H(2)SO(4), cause a significant increase in hydrogen overvoltage, the effect being stronger the higher the molecular weight. The increase could be accounted for by the usual site-blockage concept. In the case of egg albumin, a drastic increase of over 300 mv was observed at 12.5 ma/cm(2) for a concentration of only 0.01 part per million. A new mechanism is proposed in which the dielectric constant and hydrogen-ion activity are believed to be depressed in a region twice as thick as the usual transition region.