Vibrating Dropping Mercury Electrode for Polarographic Analysis of Agitated Solutions

Abstract

H E dropping mercury electrode has been limited chiefly to Tsolutions that are free from agitation, for any stirring results in irregular dropping of mercury from the capillary and consequent fluctuations in current. The shielded dropping mercury electrode (8, 11) has been successfully applied to agitated solutions, but has the disadvantage of introducing a time lag in the current readings ( 7 ) .A vibrating dropping mercury electrode was developed by this laboratory to fill the need of applying the polarographic method to biological systems requiring continuous agitation. Enforced drop electrodes, which have been developed chiefly for increasing the accuracy of the current readings or for synchronizing the drop rates of multiple capillaries, have been described by several investigators. Kanner and Coleman ( 4 ) incorporated a solenoid in the design of their apparatus as a means of initiating a new mercury drop after the current measurement. Heyrovsk4. ( 3 ) used the device developed by Cermak and Hanus ( 8 ) for obtaining derivative curves. The drop rates of the electrodes in this device were synchronized by a solenoid. Skobets and KavetskiI (9) positioned a glass hoe under the dropping mercury electrode for the purpose of controlling the drop rate, and demonstrated that it was possible with this arrangement to increase the accuracy of the current readings. None of the authors describing such enforced drop electrodes indicated, however, that their devices could be applied to stirred solutions.The vibrating dropping mercury electrode described in this paper was developed specifically for systems requiring continuous agitation. Although the device was designed primarily for measuring the oxygen uptake of contracting isolated cardiac muscle preparations, it is also suited for other analytical procedures where agitation of the solution is required.was mounted on rubber to eliminate any appreciable vibration other than that of the electrode. Only slight irregularities in current were observed (Figure 2) when the apparatus was free of secondary vibration.A comparison between polarograms of 0.001 M lead nitrate, taken with the conventional dropping mercury and the vibrating dropping mercury electrode in the absence of oxygen, is shown in Figure 2. I n the lower curve, B, taken with the vibrating dropping mercury electrode, nitrogen was continually passed through the solution. Some reduction in sensitivity is apparent with the vibrating electrode.A linear relationship between oxygen tension and current was demonstrated. Tenth molar potassium chloride containing 0.03% gelatin as a maximum suppressor was equilibrated with four gas mixtures of oxygen and nitrogen containing 99.7 * 0.2% oxygen, 49.9 * 0.2% oxygen, 20.9% oxygen (air), and 0% oxygen (nitrogen). The gas mixture was bubbled continuously into the solution during the recording of the current a t a constant voltage (-0.6 volt us. S.C.E.).The dropping mercury electrode has been successfully applied to the study of the rate of oxygen consumption of yeast by Baumb...

Rapid drop time on-line Fast Fourier Transform faradaic admittance measurements

“…The use of rapid mercury drop time (<1 s) polarographic measurements dates back at least to the early 1950's (1). Little interest was shown in this experimental strategy at first, but significant interest began to appear in the mid-1960's.…”