title: Development of an anodic stripping voltammetric assay, using a disposable mercury-free screen-printed carbon electrode, for the determination of zinc in human sweat.
abstract: This paper reports on the development of a novel electrochemical assay for Zn(2+) in human sweat, which involves the use of disposable screen-printed carbon electrodes (SPCEs). Initially, SPCEs were used in conjunction with cyclic voltammetry to study the redox characteristics of Zn(2+) in a selection of supporting electrolytes. The best defined cathodic and anodic peaks were obtained with 0.1 M NaCl/0.1 M acetate buffer pH 6.0. The anodic peak was sharp and symmetrical which is typical for the oxidation of a thin metal film on the electrode surface. This behaviour was exploited in the development of a differential pulse anodic stripping voltammetric (DPASV) assay for zinc. It was shown that a deposition potential of -1.6 V versus Ag/AgCl and deposition time of 60 s with stirring (10 s equilibration) produced a well-defined stripping peak with E(pa) = -1.2 V versus Ag/AgCl. Using these conditions, the calibration plot was linear over the range 1x10(-8) to 5x10(-6) M Zn(2+). The precision was examined by carrying out six replicate measurements at a concentration of 2x10(-6) M; the coefficient of variation was calculated to be 5.6%. The method was applied to the determination of the analyte in sweat from 10 human volunteers. The concentrations were between 0.39 and 1.56 microg/mL, which agrees well with previously reported values. This simple, low-cost sensitive assay should have application in biomedical studies and for stress and fatigue in sports studies.
authors.affiliation: Centre for Research in Analytical Materials & Sensor Science, Faculty of Health & Life Sciences, University of the West of England, Coldharbour Lane, Bristol BS16 1QY, UK.
authors.forename: A
authors.initials: A
authors.lastname: Crew
authors.forename: D C
authors.initials: DC
authors.lastname: Cowell
authors.forename: J P
authors.initials: JP
authors.lastname: Hart
mesh_terms: D001681:Biological Assay / Q000295:instrumentation / Q000379:methods*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002021:Buffers; D002244:Carbon / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012834:Silver / Q000737:chemistry; D018030:Silver Compounds / Q000737:chemistry; D013177:Sports / Q000502:physiology; D013542:Sweat / Q000737:chemistry*; D015032:Zinc / Q000032:analysis*
chemical_list: D002021:Buffers; D018030:Silver Compounds; D012834:Silver; D002244:Carbon; D008628:Mercury; D015032:Zinc; C037548:silver chloride