Selectivity Enhancement of a Bacterial Arginine Electrode

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Abstract
The selectivity of a previously reported bacterial arginine electrode was greatly enhanced, with no loss of response to arginine. The response of this sensor to glutamine and asparagine was due to a contaminant growing in the bacterial layer of the electrode. The addition of 1 .times. 10-3 M sodium azide to the working buffer and cold storage of the electrode effectively controlled the growth of the contaminating bacteria and maintained the low initial response of the electrode to these amino acids in the concentration range of 4 .times. 10-5 to 1.5 .times. 10-3 M. At these optimum conditions, the response of the sensor to arginine was unaffected by the presence of a mixture of amino acids at physiological levels.