The working electrode modification applying some specific modifiers results in capacitors formationnot related to the charges exchange occurring and double layer formation at the electrode – solutioninterface. Chemical or biochemical processes involving the modification layer cause its thicknessvariations leading to capacitance changes resulting in AC amperometric response. An ACamperometric method for lipase activity quantification based on this approach was developed andcharacterized. A thin layer of nanocomposite (SiO2 nanoparticles charged olive oil) deposited on theworking electrode served as both: sensitive layer toward the lipase and dielectric layer of anelectrolytic capacitor formed on the electrode – solution interface. The nanocomposite enzymaticdegradation by the lipase causes its thickness decrease proportional to the lipase activity and acorresponding rise of the AC current is registered as analytical response by AC amperometry at fixedsmall AC amplitude (100 mV p.p.) and frequency of 240 Hz. The developed method was characterizedin terms of: LOD, sensitivity, linear quantification range, precision, response time and reproducibility,as well as was validated by spiked samples determination using the standardized titrimetric method asreference..
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