Inkjet-printed colorimetric sensor array for the rapid identification of adulterated Fritillariae cirrhosae bulbus

As an important antitussive and expectorant herbal medicine, Fritillariae cirrhosae bulbus (FCB) is rare and expensive, leading to massive adulterations in the market. Herein, we report a solid colorimetric sensor array (CSA) method for the rapid identification of FCB and its adulterations. This CSA was fabricated by printing nine pH indicators on a mixed cellulose ester membrane via a commercially available inkjet printer filled with polyethylene glycol-containing ink. This CSA displayed color changes to various analytes, as their solution of varied pH values triggers chemical reactions with the nine pH indicators (and other potential interactions). The digital database of these colorimetric response patterns was collected automatically using a homemade program. The outstanding identification capability of the CSA was confirmed via the analysis of 1,2-diols and catechols. The principal component analysis result demonstrated that this CSA could distinguish pure FCB powder from its six common adulterations. The linear discriminant analysis models were established for the qualitative identification of adulterated FCB samples with 89.58 %− 100 % accuracy. Furthermore, partial least squares regression models were developed for the quantitation of adulterant percentages with correlation coefficients higher than 0.87. We expect that the inkjet-printed CSA provided an effective on-site screening method for identifying adulterated FCB.