The metal coated hollow fiber membrane (MCH) has been applied as a working electrode of an electrochemical detector for high performance liquid chromatography (HPLC). In this paper, the improvements of the sensitivity of the copper coated hollow fiber membrane (Cu-MCH) electrode as a sensor for carbohydrates were described. The MCH electrode had the tubular structure. Therefore, there was a problem of decreasing the output signal by dilution of analysis with the dependence on the inside volume. In order to reduce the inside volume, the plug put inside of the MCH and a thinner hollow fiber membrane were used. The plug was effective to make the MCH electrode sensitive resulting the detection limit (S/N=3) of glucose lowered from 1.7 pmol to 0.95 pmol. The hollow fiber membrane in which inside diameter was thinner was also effective. The detection limit dropped from 1.7 pmol to 0.56 pmol, when it was changed to 0.6 mm from 1.0 mm. In addition, it was effective to decrease the noise current when the hollow fiber membrane of 0.6 mm inside diameter was covered with the copper on the gold (Cu/Au-MCH).The detection limit was improved to 0.24 pmol. The simultaneous detection of sorbitol, glucose, fructose, lactose, saccharose, raffinose and maltose was demonstrated with the Cu/Au-MCH in HPLC. The detection limits were 0.39, 0.24, 0.39, 0.38, 0.58, 0.53 and 0.82 pmol, respectively.
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