Trace determination of vitamin B12 in food samples by using Fe3O4 magnetic particles including multi-walled carbon nanotubes and nanodiamonds
A sensitive and simple determination method for trace vitamin B12 molecules was developed based on magnetic solid phase extraction (MSPE) by using newly synthesized magnetic nanoparticles. Determination of target molecules after MSPE was carried out by means of HPLC-DAD systems in food samples. The proposed method has important advantages such as eco-friendliness, simplicity, sensitivity, low equipment costs, precision, and accuracy. All experimental variables including extraction time, ionic strength, desorption solvent, and desorption time were investigated in detail. The accuracy of the proposed method was checked by using the UV spectra of target molecules and retention characteristics, and by comparing the peak purity with the vitamin B12 standard. The results showed that utilization of the MSPE step could provide a sensitive (limit of detection of 2.85 ng mL−1), precise (coefficients of variation <3.60%), and accurate (recoveries >98%) method. The reused material displayed a long-term stability after undergoing extraction 10 times. Recovery values were calculated by using spiked samples and certified reference materials including multivitamin tablets (NIST 3283) and whole milk powder (ERM-BD600) were used for the validation of the results. Finally, the method was applied to food samples successively.