A biosensing method for detection of caffeine in coffee

A specific inhibition of 3',5'-cyclic phosphodiesterase (CPDE) from bovine heart by methylxanthines was used in combination with a pH electrode to dev elop a new biosensing method for the detection of caffeine in coffee. The p otential response changes of the sensor were proportional to the concentrat ion of caffeine in the range 0-4 mg ml(-1). The response time was about 2-4 min. The standard deviation of five measurements of a 0.2 mg ml(-1) caffei ne solution was 17.1 mu g ml(-1). The electrode gave a detection limit of 0 .6 mg l(-1) caffeine. The concentration of caffeine in espresso coffee was analysed. This model gave excellent correlation between observed and predic ted caffeine values. This electrode exhibits advantages such as fast respon se, short conditioning time and low cost of the instrumentation used. We al so expected to be able to perform the detection of caffeine in food and cli nical analysis. (C) 1999 Society of Chemical Industry.