Microplate-compatible biamperometry array for parallel 48-channel amperometric or coulometric measurements.
We report a new reusable electrochemical array for parallel biamperometric measurements that has been designed for use with standard microplates. The 48-channel array uses half of the available 96 wells and has 48 pairs of Pt wire electrodes. Applications to the quantitation of a variety of oxidizable species, including acetaminophen, ascorbic acid, hydroquinone, trolox, and uric acid, are demonstrated in assays that use potassium ferricyanide as an oxidant to produce a mixture of ferri- and ferrocyanide. Hydrogen peroxide quantitation is also demonstrated, based on an assay in which ferrocyanide is oxidized, again to produce a mixture of ferri- and ferrocyanide. Detection limits (signal-to-noise ratio (S/N) = 3) in these assays range from 1 (acetaminophen, R2 = 0.994) to 8 microM (ascorbic acid, R2 = 0.967), and linearity was observed to analyte concentrations of at least 100 microM. We also demonstrate the application of the biamperometric array to enzymatic assays, using the glucose oxidase reaction as an example; following a 20 min enzyme reaction time, a detection limit of 0.1 mM glucose was obtained. These results indicate that applications to other oxidase-based assays are feasible in this high-throughput format. The new electrochemical array employs standard, inexpensive microplates, and the biamperometric measurements are simple, precise, and rapid, requiring only 2 min for 48 parallel measurements.
Mann
Thomas S
TS
Rapid Laboratory Microsystems Incorporated, Freeport Health Centre, P.O. Box 9056, 3570 King Street East, Kitchener, Ontario, Canada N2P 2G5.
O'Hagan
Liam
L
Ertl
Peter
P
Sparkes
Douglas I
DI
Mikkelsen
Susan R
SR
D000082:Acetaminophen / Q000737:chemistry; D001205:Ascorbic Acid / Q000737:chemistry; D002138:Calibration; D002839:Chromans / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D005295:Ferrocyanides / Q000737:chemistry*; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D005949:Glucose Oxidase / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D006873:Hydroquinones / Q000737:chemistry; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry; D014527:Uric Acid / Q000737:chemistry
D002839:Chromans; D005295:Ferrocyanides; D006873:Hydroquinones; D014527:Uric Acid; D000082:Acetaminophen; D010984:Platinum; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; C020354:hexacyanoferrate II; D005947:Glucose; D001205:Ascorbic Acid; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; C031927:hydroquinone