Amin-modified graphene oxide as a promising adsorbent for selective extraction of dexamethasone adulterant from herbal supplements

In most cases, herbal supplements found in illegal centers and herbal medicine stores have harmful content that causes irreparable damage to people. As a representative of the green chemistry method, a rapid and efficient dispersive micro solid-phase extraction (D-mSPE) method was applied to extract dexamethasone adulterant from handmade supplements sold as power natural enhancing materials. The quantification of the analyte was performed by high performance liquid chromatography with an ultraviolet detector. Effective parameters on the extraction recovery, including the type and amount of adsorbent, the kind of elution solvent, and the time of extraction and elution, were systematically investigated. The limit of detection of the method was 0.05 μg mL(−1). Furthermore, inter-day precisions calculated as relative standard deviations were better than 10%. Ten dietary supplements, including liquid, capsule, tablet forms, and powder, were analyzed using the developed method, and four of them were detected as adulterated with dexamethasone. The developed method purifies the complex plant-based samples and results in a clean analysis with separation instruments.