Abstract
Four various biosensors based on flow enzymatic mini-reactors containing one of the two different mesoporous silica powders (SBA-15 or MCM-41) modified by one of the two enzymes (laccase or tyrosinase) were used for the determination of L-DOPA, dopamine, noradrenaline, and adrenaline. Dependences of peak currents on detection potentials, flow rates, injected volumes, reactor volumes, and analyte concentrations were studied and optimized.
The silica powder of MCM-41 with covalently bonded laccase (Lac) was found to be the best filling for the detection of catecholamines. Relative current response of such biosensor was: 100% for dopamine, 32.1% for L-DOPA, 26.2% for noradrenaline, and 0.71% for adrenaline.
Statistical evaluation of parallel determinations of studied analytes with this biosensor proved its good accuracy (RSD=1.82-5.18%) and sensitivity (5.46-15.5molL(-1)). Life time of the studied biosensors is several months.
The practical applicability of Lac-MCM41 biosensor was successfully verified by the determination of dopamine and noradrenaline in medical solutions for infusions.