Simultaneous amperometric and potentiometric detection of sugars, polyols and carboxylic acids in flow systems using copper wire electrodes

Copper wire electrodes, used for amperometric and potentiometric detection in flow injection analysis and highperformance liquid chromatography, have been developed for the 'simultaneous' detection of sugars, polyols and carboxylic acids. Sugars and polyols were oxidised at +0.5 V (versus Ag\AgCl\0.1 M Cl-) in 100 mM NaOH and citric acid was potentiometrically detected at a copper wire in Milli-Q water. Citric acid, acetic acid, glucose, fructose, glycerol and ethanol were separated by ion-exclusion chromatography with water as eluent and passed through the potentiometric detector then the amperometric detector after addition of 100 mM NaOH. The amperometric detector gave detection limits of 5, 5, 2 and 80 pmol for glucose, fructose, glycerol and ethanol, respectively, with a linear response over 3 decades (10(-6)-10(-3) M). For the potentiometric detector, the detection limits were 10 and 50 pmol for citric acid and acetic acid and linearity was in range of 10(-5) M-10(-3) M. Compared with a universal detector such as refractive index, the reported combination electrochemical detector shows high sensitivity and low detection limits.