▎ 摘　　要

In the present study, a novel quantitative method, namely solid phase extraction, was applied to extract vitamin B-12 from pharmaceutical formulations. The technique involves the use of graphene oxide (GO) as an efficient adsorbent for solid-phase extraction of vitamin B-12. Collection of GO from aqueous solution was simply achieved by applying filtration assembly. The extracted analyte was directly analyzed by using X-ray fluorescence (XRF) spectroscopy. Factors affecting the extraction efficiency were investigated and optimized. Under the optimum conditions, enhancement factor of 46, linear dynamic range of 25-1000 mu gl(-1) with correlation of determination (R-2=0.998) and limit of detection of 20 mu gl(-1) were obtained for vitamin B-12. The percent relative standard deviation based on three-replicate determination was less than 8.1%. The method was successfully applied for extraction and determination of vitamin B-12 in different types of pharmaceutical samples such as multivitamin tablet, effervescent tablet and injection sample. The results showed that the proposed method based on GO was a simple, accurate, and highly efficient approach for analysis of vitamin B-12. Copyright (c) 2014 John Wiley & Sons, Ltd.