LACTATE, GLUTAMATE AND GLUTAMINE BIOSENSORS BASED ON RHODINISED CARBON ELECTRODES

Amperometric enzyme sensors for lactate, glutamate and glutamine were constructed using rhodinised carbon electrodes. All three sensors oper ated at a potential of +400 mV (Ag/AgCl). Lactate sensors were constru cted using lactate oxidase immobilized in hydroxyethylcellulose, overl aid with a cellulose acetate membrane. Using a flow-injection system, the sensors had a linear range of 0.1 to 1.5 mM. Measurements of lacta te concentrations from a mammalian cell culture were compared with res ults obtained from a commercial instrument. A correlation coefficient of r=0.982 (n = 15) was obtained. Glutamate and glutamine sensors were fabricated based on glutaraldehyde immobilization; the former by inco rporating glutamate oxidase and the latter based on glutamate oxidase and glutaminase (both had a linear range of 0.1 to 1.5 mM). The feasib ility of using these sensors, in conjunction with a previously describ ed glucose sensor, for mammalian cell culture monitoring is discussed