Developing a novel paper-based enzymatic biosensor assisted by digital image processing and first-order multivariate calibration for rapid determination of nitrate in food samples

JALALVAND, ALI R.; MAHMOUDI, MAJID; GOICOECHEA, HECTOR C.

RSC Advances

RSC

Lugar: Londres; Año: 2018 vol. 8 p. 23411 - 23420

For the first time, a novel analytical method based on a paper based enzymatic biosensor assisted by digitalimage processing and first-order multivariate calibration has been reported for rapid determination ofnitrate in food samples. The platform of the biosensor includes a piece of Whatman filter paperimpregnated with Griess reagent (3-nitroaniline, 1-naphthylamine and hydrochloric acid) and nitratereductase. After dropping a distinct volume of nitrate solution onto the biosensor surface, nitratereductase selectively reduces nitrate to nitrite and then the Griess reagent selectively reacts with nitriteto produce a red colored azo dye. Therefore, the color intensity of the produced azo dye is correlatedwith nitrate concentration. After image capture, the images were processed and digitized in the MATLABenvironment by the use of an image processing toolbox and the vectors produced by the digital imageprocessing step were used as inputs of the first-order multivariate calibration algorithms. Severalmultivariate calibration algorithms and pre-processing techniques have been used to build multivariatecalibration models for verifying which technique offers the best predictions towards nitrateconcentrations in synthetic samples and the best algorithm has been chosen for nitrate determination inpotato, onion, carrot, cabbage and lettuce samples as real cases.