It acts as a strong electrophile which reacts with the electron-rich α-carbon (2-position) of indole rings to form a blue-colored adduct.

Not all indole alkaloids give a colored adduct as result of steric hindrance which does not allow the reaction to proceed.

If a urine sample is left to oxidize in air to form urobilin the reagent will not detect the urobilinogen.

By adding few drops of reagent to 3 mL of urine in a test tube one can see a change of color, to dark pink or red.

[4] Isaac Asimov, in a 1963 humorous essay entitled "You, too, can speak Gaelic",[5] reprinted in the anthology Adding a Dimension among others, traces the etymology of each component of the chemical name "para-di-methyl-amino-benz-alde-hyde" (e.g. the syllable "-benz-" ultimately derives from the Arabic lubān jāwī (لبان جاوي, "frankincense from Java").