Can the HI83730-01 be used to measure peroxide value in essential oils?

As long as the essential oils are not highly colored, this photometer should work.

Peroxide value methodology is common among all oils and the photometer works along with the same principles as the titration. Essential oils tend to have higher concentrations of phenolic compounds, which could cause an issue as they can interact with one of the reagents used in the test. However, the reaction between phenolics and the reagent is pH-dependent, and as the sample has acetic acid added to it, the potential interference should be mitigated.