Sustainable downscaled chemical and pharmaceutical analysis employing micro-liter solution handling and renewable...

Sustainable, downscaled approaches that integrate microliter-volume-scale solution handling and exploit renewable natural materials were developed. Two simple and cost-effective setups were proposed using acid-base titration as a proof-of-concept model. The concept was demonstrated by a simple flow using a simple peristaltic pump for titrant and a microwell plate reactor, another being a non-flow system composed of a micropipette tip as a reactor. The first system was demonstrated for true titration, while the latter was for pseudo-titration. Steamed glutinous rice grains (GS) sorbed with an indicator were employed in both systems. With image processing, the color change of the indicator sorbed on GS was monitored for endpoint detection for true titration, while providing a calibration graph of pseudo-titration. These lead to the evaluation of analyte concentrations. The indicator-sorbed GS demonstrated reusability for at least five titration cycles, supported by both analytical performance and SEM evaluation of physicochemical characteristics during the raw material, sorption, and titration stages. Proof of concept demonstrated real-world applications for commercial food (vinegar and vegetable oil) and pharmaceutical (drug and supplement) samples, showing no significant difference compared with the conventional titration at the 95% confidence level. The proposed approach was evaluated for greenness and sustainability (AGREE, BAGI, and NQS indices).