AS/NZS 1301.11S:2005

This Standard describes a method for determination of Klason lignin. The lignin content should not be less than 1 per cent to provide a sufficient amount of lignin, about 20 mg, for accurate weighing. It is not applicable to bleached pulps containing small amounts of lignin.

Lignin is the aromatic amorphous material found in the cell wall and middle lamella of a wood fibre [1] and [2]. Its removal is the main objective of chemical pulping and bleaching processes.For the purpose of this Standard, Klason lignin is defined as those components of wood or pulp which are insoluble after treatment with 72 per cent m/m sulphuric acid followed by boiling in 3 per cent sulphuric acid. This Standard describes a method for determination of Klason lignin. The lignin content should not be less than 1per cent to provide a sufficient amount of lignin, about 20mg, for accurate weighing. It is not applicable to bleached pulps containing small amounts of lignin.Most woods contain some lignin which is rendered soluble by the above treatment and which is not determined by this Standard. In softwoods and sulphate pulps this soluble lignin content is small, about 0.2 to 0.5 per cent, but in hardwoods it can amount to 5 per cent. In semi-bleached pulps about one-half of the total lignin content could be acid soluble. The filtrate obtained during performance of this test may be used for determination of acid-soluble lignin (see NOTE 2).Hardwoods contain appreciable quantities of alkali soluble lignin so hardwood which has had any alkali treatment, may give a lower result than would be obtained on the untreated wood. Some eucalypt woods contain polyphenolic substances which are included in the acid insoluble lignin if not removed prior to the test [3].

First published in Australia as AS 1301.P11s-1978.Jointly revised and redesignated as AS/NZS 1301.11s:2005. Originated in Australia as AS 1301.P11s-1978. Jointly revised and redesignated as AS/NZS 1301.11s:2005.