title: Operational parameters of voltammetric high-performance liquid chromatographic detectors with copper electrodes and application to a determination of some fodder biofactors.
abstract: Two versions of an amperometric detector with a copper working electrode have been constructed and tested for high-performance liquid chromatography (HPLC). The performance of the detectors was studied using selected amino acids. The dependence of the detector response on the mobile phase flow-rate was studied in the range common in both macro- and microcolumn HPLC (5 microliter/min to 1.0 ml/min). It has been found that the detection sensitivity generally increases with decreasing flow-rate, i.e., the detector response is governed by the rate of the complexation reaction between the cupric ions and the solutes. This fact makes amperometric detection with a copper electrode especially useful for microcolumn separations. For all 20 amino acids studied, calibration curve parameters and detection limits have been determined; the latter vary from 0.4 to 18 ng in the injected volume. The amino acids can also be sensitively detected in a medium of 0.1-1.0 M ammonia, which is promising for the use of strong anion exchangers in amino acid separations. Choline can also be detected at a copper electrode, with a detection limit of 40 ng. An HPLC method with amperometric detection at a copper electrode has been developed for the determination of lysine, methionine and choline in fodder biofactors.
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D000641:Ammonia / Q000032:analysis; D000821:Animal Feed / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D003300:Copper; D004566:Electrodes
chemical_list: D000596:Amino Acids; D000641:Ammonia; D003300:Copper