Identifying an emergent adulterant hydrochlorothiazide in food: A simple lateral flow strip with high sensitivity by time-resolved fluorescence

Hydrochlorothiazide, an antihypertensive and diuretic drug only for clinic purpose, was recently found as an adulterant in functional foods. Due to the potential health risk, it is urgent to develop a simple and rapid assay for its identification. In this work, two hapten structures were rationally designed based on molecular modeling, and a highly sensitive antibody to hydrochlorothiazide was obtained with 50% inhibitive concentration (IC50) of 6.7 ng/mL for the first time. A lateral flow strip assay was then developed based on time resolved fluorescence, demonstrating a cut-off value of 250 μg/kg to hydrochlorothiazide in functional capsules and tablets, and a negligible cross-reactivity to related compounds. The strip performance for real samples collected from the retail markets was consistent of that of confirmed method (LC-MS/MS). As an ideal tool, the proposed strip could be applied to identify adulterated hydrochlorothiazide in functional foods.