Development of a rapid colorimetric method for detection of synthetic corticosteroids in food and dietary supplements

Synthetic corticosteroids such as dexamethasone and prednisolone are widely used for the treatment of various conditions including tumors and skin disorders. Chronic exposure to synthetic corticosteroids leads to adverse health effects such as osteoporosis, hyperglycemia and hypertension. Several dietary and health supplements have recently been reported to be adulterated with synthetic corticosteroids. Conventional analytical techniques such as high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC) and immunochromatography used for detection of these corticosteroids are time-consuming and require trained personnel, necessitating the development of rapid and cost-effective screening methods to ensure food safety. Here, a rapid and cost-effective colorimetric recognition chemistry has been developed for detection of synthetic corticosteroids in dietary supplements. The method employs spectrophotometric quantification of the chromogenic end product at 410 nm, which was further assessed using RGB-based image analysis. Selectivity and interference studies showed no significant matrix interference from the tested structurally similar steroids and common dietary supplement samples. The assay demonstrated a limit of detection (LOD) of 0.04 ± 0.008% (w/v) and a limit of quantification (LOQ) of 0.12 ± 0.027% (w/v) for prednisolone. The developed method is suitable for on-site detection of synthetic corticosteroids, and can be used by regulatory agencies and industries to ensure food safety and human health.