Further observations on ninhydrin-reacting compounds in urine

Abstract

THE MOST COMMON abnormal ninhydrin-reacting compound observed in the urine of patients screened for inborn errors of amino acid metabolism has been, in our experience, ampicillin. 1 When high concentrations of this drug are administred intravenously, an ampicillin crystalluria may occur) The recent correspondence in THE JOURNAL of PEDIATRICS 23 regarding the discovery of spurious ninhydrin-positive peaks in the ion exchange chromatography of the urine of a patient being treated with ampicillin has prompted us to record our investigations with a number of rather commonly used drugs or related compounds which yield a color with the ninhydrin reagent. Under certain conditions, these compounds could be a source of confusion in the interpreta t ion of amino acid excretion patterns. Although only the techniques of paper chromatography and paper electrophoresis were examined, the same considerations would apply to any method which utilized ninfiydrin to locate and quantitate amino acids.