Facile immunochromatographic assay based on metal–organic framework-decorated polydopamine for the determination of hydrochlorothiazide adulteration in functional foods

•A MOF@PDA-ICA was firstly developed for the detection of HCTZ in functional foods.•The sensitivity of MOF@PDA-ICA was 27-fold higher than that of the similar method.•A portable smartphone-based detection device was used for rapid quantification. Herein, a novel immunochromatographic assay (ICA) based on metal–organic framework-decorated polydopamine (MOF@PDA) was firstly developed for the determination of hydrochlorothiazide (HCTZ) adulteration in functional foods. The coupling rate of MOF@PDA carrier to HCTZ antibody was as high as 91.7 %. The detection limits of the developed MOF@PDA-ICA in functional tablets and capsules were 5.93 and 4.72 μg/kg, the linear ranges were 11.2–91.91 μg/kg and 9.11–86.78 μg/kg, respectively. The sensitivity was 27-fold higher than that of the reported ICA. The recovery was 82.5–116.6 %, and coefficient of variation was 6.9–14.2 %. The results can be achieved and analyzed in 8 min with the smartphone-based detection device. The parallel tests of 23 commercial functional tablets and capsules showed that the results of the MOF@PDA-ICA were consistent with that of the LC-MS/MS (R2 > 0.99). Therefore, our method is facile, sensitive, portable, and can provide a reliable technical mean for the detection of HCTZ adulteration in functional foods.