Apparent inter-channel interference in dual-electrode electrochemical detection.
During the course of routine high-performance liquid chromatographic analyses of brain catecholamines using dual-electrode electrochemical detection, we encountered an unusual negative peak in the lower-voltage channel. Subsequent investigations suggested that this peak was caused by tyrosine which produced a positive peak in the higher-voltage channel. Our investigations indicate that compounds that generate a peak in one channel appear to be responsible for complex peaks in a second channel set at a lower voltage, close to or below that necessary for oxidation. The complex peaks are biphasic; a sharp negative peak coinciding with the positive peak on the higher-voltage channel, followed by a positive peak. This effect was not specific for tyrosine, but was observed on the lower-voltage channel with all compounds tested that produced signals on the high-voltage channel. The cause of the problem is unknown, but it appears to be an artifact of the electrical coupling of the two electrode channels in a dual-channel system.
Dempsey
C A
CA
Department of Pharmacology and Therapeutics, Louisiana State University School of Medicine, Shreveport 71130-3932.
Lavicky
J
J
Dunn
A J
AJ
D000818:Animals; D001923:Brain Chemistry; D001933:Brain Stem / Q000737:chemistry; D002395:Catecholamines / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods / Q000592:standards*; D004563:Electrochemistry; D004566:Electrodes; D051379:Mice; D014443:Tyrosine / Q000737:chemistry
D002395:Catecholamines; D014443:Tyrosine