A SPECIFIC HYDROXYLAMINE-FERRIC CHLORIDE REACTION FOR HISTOCHEMICAL LOCALIZATION OF PECTIN

An alkaline solution of hydroxylamine is caused to react with the methyl esters of pectin present in sections of plant tissues to produce hydroxamic acids which, after acidification with hydrochloric acid, yield a red color upon addition of 2.5% ferric chloride solution. The test is specific and preferable to the use of ruthenium red for localization of pectin in the compound middle lamella. Subjecting sections to methylation and using reagents made up in 60% alcohol increases the intensity and sharpness of the color formation.