Effective improvement in performance of a miniature FIA-calorimetric biosensing system via denoising column addition and flow rate optimization

The noise reduction and heat-response improvement of a miniature FIA-calorimetric biosensing system were evaluated for the determination of enzyme activity. An innovative denoising column was designed in combination with the use of a mathematical moving average for effectively decreasing signal noise from 30 mV to 0.2 mV. Additionally, various flow rates were tested for a comprehensive analysis of the influence of the flow rate on the heat response of this system. As the flow rate rose in the 0.1-0.5 mL/min range, the temperature sensitivity of the calorimetric system increased linearly from 0.8 mV/K to 1.184 mV/K, showing an improvement of 48%. However, the exothermic peak integral reached the highest point at the flow rate of 0.3 mL/min, when the system was used to detect the heat release of hydrolysis reaction catalysed by chicken liver esterase. Thus, the flow rate of 0.4 mL/min was finally employed in this system. The biosensor was successfully applied for the detection of malathion, where 0.01 mg/L malathion was detected significantly. Thus, this biosensor could potentially be used for the determinations of inhibitors based on enzyme inhibition methods.