An in-line, accurate and precise procedure is being developed for monitoring ethanol and sugar levels in fermentation and other processes. The sensor systems must display sensitivity and selectivity with respect to alcohols and sugars, but must be insensitive to fouling and passivation from interfering substances in the solution.
Tests to date have indicated that all carbohydrates and ethanol can be detected electrochemically and optimum results have been observed at platinum microarrays of which over eighty different configurations have been tested. The usual drawback with mircroelectrodes is the low current signals. However, this problem has been negated by the use of an array that generates an enhanced signal. A pulsed amperometric technique is used for electrode cleaning and pre-treatment. The pH dependence of glucose/ethanol detection means that it does not lend itself to oxidation in fermentation media where the pH is usually neutral to acidic. This problem has been addressed by investigating ways of obtaining pH independence using overlaying coatings. Barriers have been developed which can confer pH independence to the sensors. Such barriers also offer a degree of selectivity with respect to ethanol detection over glucose.