Resonance light scattering combined with miniaturized Thermal-Assisted Purge-and-Trap device for screening of hydrochloride drugs.

Resonance Light Scattering (RLS) is a sensitive analytical technology hindered by its susceptibility to impurities in complex samples. This study introduces a combination of RLS with a high-efficiency sample preparation device, the Miniaturized Thermal-Assisted Purge-and-Trap (MTAPT), enhancing RLS's effectiveness in complex sample analysis. Specifically, we utilized MTAPT-RLS for the indirect screening of illegal hydrochloride drug additions in health products, based on three considerations: the transformation of bound HCl in hydrochloride drugs into volatile HCl under strong acid and heat; the minimal Cl content in health products for taste purposes; and the detectability of Cl ions by RLS upon the addition of AgNO₃ and a stabilizer. Employing RLS, this method quantifies Cl elements via fluorescence signals, achieving a linear response (R = 0.9984) across 5.0-80.0 μg/mL and a recovery rate of 94.1-114.0 % across three sample types. With a detection limit of 2.0 μg/mL, this approach exceeds traditional rapid detection methods in speed and sensitivity, offering substantial benefits for food safety monitoring. Additionally, we developed a smartphone-based detection system utilizing RGB signal changes captured by smartphone cameras, coupled with a custom app. This system shows a linear response (R = 0.9888) within the same concentration range and detection limit. Notably, the green light source provided the highest sensitivity, aligning with the RLS peak at approximately 520 nm. With its excellent portability, this method is well-suited for on-site rapid detection, independent of bulky analytical instruments.