Simultaneous analysis of some volatile compounds in food samples by array gas sensors based on polypyrrole nano-composites

Purpose - The purpose of this paper is to construct an array of sensors using polypyrrole-zinc oxide (PPy-ZnO) and PPy-vanadium (V; chemical formula: V2O5) fibers. To test responses of sensors, a central composite design (CCD) has been used. The results of the CCD technique revealed that the developed sensors are orthogonally sensitive to diacetyl, lactic acid and acetic acid. In total, 20 different mixtures of diacetyl, lactic acid and acetic acid were prepared, and the responses of the array sensors were recorded for each mixture. Design/methodology/approach - A response surface regression analysis has been used for correlating the responses of the sensors to diacetyl, lactic acid and acetic acid concentrations during the gas phase in food samples. The developed multivariate model was used for simultaneous determination of diacetyl, lactic acid and acetic acid concentrations. Some food samples with unknown concentrations of diacetyl, lactic acid and acetic acid were provided, and the responses of array sensors to each were recorded. Findings - The responses of each sensor were considered as target response in a response optimizer, and by an overall composite desirability, the concentration of each analyte was predicted. The present work suggests the applicability of the response surface regression analysis as a modeling technique for correlating the responses of sensor arrays to concentration profiles of diacetyl, lactic acid and acetic acid in food samples. Originality/value - The PPy-ZnO and PPy-V2O5 nanocomposite fibers were synthesized by chemical polymerization. The provided conducting fibers, PPy-ZnO and PPy-V2O5, were used in an array gas sensor system for the analysis of volatile compounds (diacetyl, lactic acid and acetic acid) added to yogurt and milk samples.