1. According to IUPAC nomenclature of organic chemistry, the hydronium ion should be referred to as oxonium.

2. The resulting Aurated oxonium ions IIIa and IIIb can then eliminate a proton to form the Aurated vinyl ethers IV

3. Anthocyanidins are common plant pigments, the sugar-free counterparts of Anthocyanins.They are based on the flavylium cation, an oxonium ion, with various groups substituted for its hydrogen atoms

4. Amides - primary Amides show a base peak due to the McLafferty rearrangement (for straight chain Amides with more than three carbons, McLafferty gives base peak at 59 = amine to generate oxonium ion (could be primary radical, secondary amine radical, or tertiary amine radical)