Exploiting a Simple Water Extract of a Flower as a Natural Reagent for Acidity Assay Using a Lab-on-Chip

A simple water extract of a flower was exploited as a natural reagent for acidity assay. The natural reagent from Gomphrena globosa was obtained by simple extraction and introduced into a simple lab-on-chip (LOC). The natural reagent adjusted to pH 9 was loaded into the vertical channel of the LOC, and then acetic acid standard/sample was injected into the horizonal channel of the LOC. The injected acetic acid solution migrated downward and merged with the natural reagent. The absorbance spectrum was monitored at the detection point. A liner calibration curve for acetic acid was obtained in the range of 3–7 % (w/w). The proposed method was applied to the determination of acetic acid in vinegar samples.