usual electrochemical significance. Values of X{at)\/ for various potentials have been published by Nicholson and Shain for the first-order case (21), and by Shuman for the second-order case (15). Cyclic voltammograms were recorded for various concentrations of Hg(II), an example being shown in Figure 2. Assuming that the reaction is secondorder, the diffusion coefficient of Hg(II) was calculated to be 0.13 =h 0.01 X 10-5 cm2 sec-1, which is in good agreement with results obtained at the RPDE. The shape of the linear scan voltammogram (curve a) is also characteristic of the second-order process. Values for ( /2 -Ep) of 0.079 V agree well with the value of 0.080 V predicted by Shuman (after correction for temperature). Finally, a plot of log C vs. Ev yielded a slope of 0.048 V in agreement with the value of 0.052 V predicted for the second-order reaction. The peak potential was independent of sweep rate over the range studied (0.025-0.30 V sec-1), and the peak height was directly proportional to concentration. The shape and position of the curve obtained on reversal (curve b) supports the above contention. These observations confirm the reduction of Hg(II) to dimeric Hg(I) to be reversible under these experimental conditions on a platinum surface. Table II. Verification of i -1/2 Dependence for Reduction of Hg(II) to Hg(0) at RPDE. [A = 8.8 X 10-3 cm2, C = 1.0 mM Hg(II)] U, µ , (measured at -0.05 V vs. Ag/Ag+) , (rad sec-1)
This communication describes the presence of 1-methyl-beta-carboline (harman) in the hypophysiotropic area of the hypothalamus which incorporates the arcuate nucleus. Diethyl ether extracts of borate-buffered arcuate homogenates were subjected to silica column chromatography and thin-layer chromatography (TLC). Identification of the beta-carboline was accomplished by use of fluorescent spectrometry, gas chromatography (GC), mass spectrometry (MS) and combined gas chromatography-mass spectrometry (GC-MS).
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