Abstract:

In this study, the thiamine (vitamin B1) content of nutritional supplements was determined according to the
Chinese national standard GB/T 5009.84—2003: Determination of Thiamine (Vitamin B1) in Foods. By analyzing the sources
of uncertainty in the determination of thiamine, we obtained the uncertainty components and finally calculated the combined
standard uncertainty and expanded uncertainty. The results showed that thiamine content in the sample was 0.49 mg/100 g,
and the expanded uncertainty was 0.052 mg/100 g. The uncertainty of standard curve fitting was the most important
component of the combined standard uncertainty. Therefore, more attention should be paid to standard curve fitting in order
to obtain more accurate results for the determination of thiamine in nutritional supplements.

Key words: uncertainty, thiamine, nutritional supplements