Results
The compound 2-hydroxy-4-methoxybenzaldehyde was identified as the artifactual alkaloid precursor. Its isomers (vanillin and isovanillin) do not show detectable reactivity toward ammonia. Mass spectrometry and TLC analyses confirmed the reactivity of 2-hydroxy-4-methoxybenzaldehyde toward dopamine, γ-aminobutyric acid, norepinephrine and serotonin.