Moisture determination in the flour samples by gas sensor based on polypyrrole-ZnO nanocomposite

Nanostructure polypyrrole (PPy) (50-10 nanometers) and polypyrrole-ZnO (PPy-ZnO) nanocomposite (30-120 nanometers) were synthesized on the commercial polyester fiber by chemical polymerization at room temperature. The synthesized fibers were used as humidity sensor to detect and determination of moisture of flour samples. Headspace method was used to sampling and injection of flour moisture to designed sensor. Results showed that PPy and PPy-ZnO sensor have the good ability to the determination of flour moisture but PPy-ZnO sensor has better response and is more sensitive than the PPy sensor. An experimental design based on central composite design (CCD) was used to study and optimize some factors like flour mass, time and temperature of sampling that affect determination and analysis of flour moisture. Results showed that the optimum condition based on fiber type (PPy or PPy-ZnO fiber) is different. In the optimum condition figure of merits of sensors to determination of humidity were calculated. PPy and PPy-ZnO sensor easily could determine flour humidity from 0.01 to 0.25 %.