However, in real-world chemistry, reagents are rarely perfect. The blank titration measures the "background noise" of the experiment. It accounts for any iodine that is liberated not by the peroxides in the oil, but by impurities in the reagents or environmental factors.
Lipid samples often contain (e.g., tocopherols, BHT). These reducing agents can react with I₂ before it is titrated: [ I_2 + AH_2 \rightarrow 2I^- + A ] in real-world chemistry
In all official methods, the Net Titre is calculated as: the Net Titre is calculated as: