ANALYSIS OF PYOCYANIN FROM PSEUDOMONAS-AERUGINOSA BY ADSORPTIVE STRIPPING VOLTAMMETRY

We have developed an adsorptive stripping voltammetric (AdSV) method t hat can be used for analysis of pyocyanin at the nanomolar level. The method employs a hanging mercury drop electrode (HMDE) as a working el ectrode in a three-electrode system in a 15-mL quartz cell. Preconcent ration of pyocyanin in a 10-mM ammonia buffer (pH 8.0) on the HMDE is carried out by adsorption under conditions of controlled mass transfer for 60 sec, followed by scanning the electrode potential that results in reduction (cathodic scan) or oxidation (anodic scan) of the accumu lated pyocyanin. For analysis of pyocyanin in samples containing a sig nificant amount of surface-active species from a bacterial culture bro th, a positive-going (anodic) potential scan must be applied after an adsorption at -0.50 V. Anodic scan of the adsorbed pyocyanin provided a well-defined oxidation peak at a potential of -0.17 V. The ''anodic scan'' variant of the method was tested for utility in Mueller-Hinton broth diluted from 20 to 200 times in a 10-mM ammonia buffer. Reproduc ibility of the method as applied to the analysis of pyocyanin produced by Pseudomonas aeruginosa (18.83 +/- 0.32 mu M) in culture was demons trated by the within-day and day-to-day coefficients of variation of 1 .7% and 3.4%, respectively. (C) 1996 Elsevier Science Inc.