Simple detection of crude fiber

Crude fiber simple method test said that 2-5g (w) sample in the 500ml high beaker, pour 1.25% boiling sulfuric acid 200ml slightly boiling 30min, (mark, when the liquid is lower than the mark, add water to the mark to ensure the concentration). Time is up, filter on the 200 mesh yarn net and rinse with hot water, wash until the filtrate is added with barium chloride without white precipitation, put the sample back into the 500ml high beaker (pay attention to operation, do not throw away the sample), add boiling 1.25% sodium hydroxide 200ml, slightly boiling 30min (and mark, add water to the mark when the liquid is lower than the mark). Time is up, fast weighing (w0) filter paper at 130℃ baking 40min (be careful not to throw away the sample). Rinse with 200ml hot water. Rinse the sample with 60 ℃ ethanol 20ml, then rinse the sample with 20ml ether (degreasing), then put the filter paper into the crucible and bake in the oven for 130℃ for 2 hours, take out and put into the dryer 30min, weigh it (W2), put it in the electric furnace and carbonize until smokeless. Put into muffle furnace 550℃ 30min and calcined to carbon-free. Put in the dryer 30min and weigh it (W1). Results (%) = {(W2-W1-w0) / W} * 100W2-is 130 ℃ drying weight, W1-is calcined weight, W0-is filter paper weight and W-is sample quality. -- sofa-- how accurate is it? Have you ever done a comparative experiment-- our parallelism is still good.