Continuous and Online Detection of Melamine, 6-Thioguanine and Histamine Using Silver Colloid-Based SERS

Surface-enhanced Raman scattering (SERS) based on noble metal nanoparticles has garnered significant attention in analytical chemistry due to its simplicity and rapidity for low-concentration detection. Although widely applied in fields like environmental monitoring, food safety, and biomedical diagnostics, the impact of silver nanoparticle shape on SERS performance remains insufficiently studied. Furthermore, traditional stationary solid and liquid SERS approaches are limited by inconsistent reproducibility and temporal variations in uniformity, respectively. To overcome these limitations, we introduce a simple continuous and online Ag SERS platform that employs spherical silver colloids within a capillary-Teflon tube system for dynamic, real-time analyte detection. Continuous fluid flow reduces variations in colloids, ensuring uniformity, while the enclosed system limits dynamic behaviors of colloids, enhancing stability. This platform demonstrates outstanding stability, with relative standard deviations of 2.30%. Its versatility is showcased through the quantitative detection of melamine in milk, 6-thioguanine in serum, and histamine in beer, demonstrating its capability for accurate, real-time detection in complex food matrices. This continuous and online Ag SERS platform represents a significant advancement in reliable, high-performance analyte detection, offering promising prospects for real-time analytical applications and providing a cost-effective, scalable solution for widespread use.