Fluorescence detection of vitamin B12 in human plasma and urine samples using silver nanoparticles embedded in chitosan in micellar mediaElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ay01297g

Herein, a novel fluorescence method has been developed for the determination of vitamin B12. The method is based on the interaction of vitamin B12 with silver nanoparticles embedded in chitosan (AgNPs–CH) followed by cloud point extraction using Triton X-100 as the nonionic surfactant followed by fluorescence detection. For fluorimetric detection, different excitation wavelengths were applied and an excitation wavelength of 250 nm and an emission wavelength of 337 nm were selected. The effect of different variables on the fluorescence intensity such as the pH of the sample solution, surfactant concentration, incubation temperature and time, electrolyte concentration and amount of AgNPs–CH was investigated. Under the approved conditions, a linear calibration curve was validated in the range of 0.2–15.0 ng mL−1of vitamin B12. The limit of detection (LOD) and the limit of quantification (LOQ) based on three and ten times the standard deviation of the blank were 0.036 and 0.119 ng mL−1, respectively. The relative standard deviation for eight replicate measurements of 1.0 and 7.0 ng mL−1of vitamin B12 was 2.92 and 2.45%, respectively. This probe was used for vitamin B12 determination in human plasma and urine samples with acceptable results and good recoveries.