Aldehydes are not commonly found in biological samples, so their presence is an important indicator of oxidative damage. Our blue-, green-, and far red-fluorescent hydroxylamines (A30627, A30629, and A30632, respectively) are superior reagents for detecting aldehydes in proteins and DNA. Fluorescent hydroxylamine derivatives react more readily with aldehydes at physiological pH than do other primary amine-containing reagents such as hydrazides. And in contrast to the traditional method of aldehyde detection—using the biotin-containing hydroxylamine derivative ARP (aldehyde-reactive probe) followed by a fluorescent dye- or enzyme-conjugated streptavidin—fluorescent hydroxylamines allow you to directly detect aldehydes in a single step. Unlike ARP, the fluorescent hydroxylamines are not expected to be cell permeant and are therefore not recommended for detecting abasic sites in live cells.