A. Reagents

Sulfuric acid (72% by weight) - ANKOM Technology - FSA72 or mix manually by standardizing reagent grade H2SO4 to specific gravity 1634 g/L at 20 ° C or 24.00N: Add 1200g H2SO4 to 440 ml H2O in 1 L MCA volumetric flask with cooling. Standardize to 1634 g/L at 20° C by removing solution and adding H2O or H2SO4 as required.

B. Safety Precautions - See MSDSs in ringed binder near eye wash station

(a) Acetone is highly flammable. Use fume hood when handling acetone and avoid inhaling or contact with skin. Insure that all the acetone has evaporated before placing in the oven.

(b)Rubber gloves and face shield should be worn when handling sulfuric acid. Always add sulfuric acid to water. If acid contacts skin, wash with copious amounts of water.

C. Apparatus

(a) Filtration device - ANKOM Technology - F57 Filter Bags.

(b) Impulse bag sealer - ANKOM Technology - 1915 Heat Sealer.

(c) Desiccator- ANKOM Technology MoistureStop weigh pouch - F39

(d) 2L & 3L Beaker

D. Procedure

Weigh Filter Bag (W1) and zero balance.

(a) Weigh 0.5 g (±0.05 g) of air-dried sample (W2), ground to pass through a 1mm screen, directly into Filter Bag. Weigh and seal one (1) blank bag and include in digestion to determine blank bag ash correction (C1).

(b) Seal the bags closed within 1cm from the open edge using the heat sealer.

(c) Spread sample uniformly inside the filter bag by flicking the bag to eliminate clumping.

(d) Perform ADF determinations using Fiber Analyzer.

(e) After performing ADF determinations, place dried bags/samples into 3L beaker and add sufficient quantity (approximately 250 ml) of 72% H2SO4 to cover bags. IMPORTANT: Bags must be completely dry and at ambient temperature before adding concentrate acid. If moisture is present in the bags, heat generated by the H2SO4 and H20 reaction will affect the results (sample inside bag will char).

(f) Place 2L beaker inside 3L beaker to keep bags submerged. Agitate bags at start and at 30-minute intervals by pushing and lifting 2L beaker up and down approximately 30 times.

(g) After 3 hours pour off H2SO4 and rinse with hot (90-100° C) H2O to remove all acid. Repeat rinses until pH is neutral. Rinse with approximately 250 ml of acetone for 3 minutes to remove water. WARNING: Do not place bags in the oven until acetone is completely evaporated.

(h) Complete drying in oven at 105° C for at least 2 hours. Longer drying period may be required depending on oven and frequency of sample introduction into the oven. Remove bags from oven and place directly into MoistureStop weigh pouch and flatten to remove air. Cool to ambient temperature and weigh bags (W3). Ash entire bag in pre-weighed beaker (30 or 50 ml) at 525° C for 3 hours or until C-free, cool and calculate weight loss (W4). Calculate blank bag ash correction (C1) using weight loss upon ignition of a blank bag sequentially run through ADF and lignin steps.

E. Calculate percent: