Xylenol orange

Xylenol orange is an organic reagent, most commonly used as a tetrasodium salt as an indicator for metal titrations. Historically, commercial preparations of it have been notoriously impure, sometimes consisting of as little as 20% xylenol orange, and containing large amounts of semi-xylenol orange and iminodiacetic acid. Purities as high as 90% are now available.