In order to check the impact of the final pH on the analysis, samples were adjusted to different pH values between pH 3 and pH 11. The samples were analyzed as described in the Section 2. The results indicated that the best pH prior to the immunoaffinity step is pH 7. At this pH, the highest vitamin B12 concentrations in the Hippophae rhamnoides samples were found. Thus, all further analysis was performed with a sample adjustment to pH 7 prior to the immunoaffinity step.