Determination of methylene blue by resonance light scattering method using silica nanoparticles as probe

A simple and novel method was developed to determine methylene blue (MB) by resonance light scattering (RLS) using silica nanoparticles (SiO₂NPs) as the probe. It was found that MB could enhance the RLS intensity of SiO₂NPs. Moreover, the increase in RLS intensity was linear with the concentration of MB over the range of 0.01-3.0μg mL^-1. The limit of detection (LOD) was as low as 4.36 ng mL^-1 (3σ) and the relative standard deviation (RSD) was 2.4% (n=6). Under the optimum experimental conditions, this proposed method was successfully applied for the determination of MB in aquaculture samples with recoveries between 96.3% and 107%. Possible mechanisms for the RLS enhancement of SiO₂NPs in the presence of MB were also discussed.