If we add the hydrogen peroxide with a graduated cylinder that had vinegar in it the sample could get contaminated with an acid or base oil or all of the above

Sample could get contaminated with an acid. because vinegar contains acetic acid. Acetic acid is the second simplest carboxylic acid (after formic acid) and consists of two small functional groups, an acetyl group (sometimes symbolized as Ac) and a hydroxyl group (AcOH); it can also be viewed as a methyl group and a carboxyl group linked. It is an important chemical reagent and industrial chemical