Lignin methods based on an acid‐detergent fibre pre‐extraction were evaluated for grass, straw, heather and spruce litter. Quantification following oxidative attack to destroy the lignin by permanganate proved to be unreliable for the woody heather material and spruce litter. In contrast the method of isolation involving hydrolysis of the cellulose component with 72% sulphuric acid (H2SO4) was precise and robust. The acid detergent reagent dissolves most of the hemi‐cellulose and offers the opportunity to quantify the residual alpha‐cellulose fraction.