A Study of the Effect of Reducing Conditions on the Amount and Nature of Lignin Isolable From Plants

The effects of maintaining reducing conditions during both the pretreatment procedures and the final determination of lignin in plant tissues have been investigated. In studying the effects produced, consideration has been given, not only to the quantity of lignin obtained, but also to its quality as judged by its methoxyl and nitrogen contents. The introduction of hydrogen sulphide during the pretreatment procedures had little or no effect on the amount or the composition of the lignin fraction isolated from freshly harvested oat plants. With air-dried timothy, introduction of the hydrogen sulphide apparently prevented in a large measure the usual interference by nitrogen-containing substances. The presence of hypophosphorous acid in the 72% sulphuric acid had no effect on the final results. Constant boiling hydriodic acid was unsatisfactory as a substitute for 72% sulphuric acid in the final determination.