3. Reducing sugar
   (1) basic lead acetate solution to take basic lead acetate 80g, so dissolved in 220 ml of water and stirred overnight, filter No. 42 filter paper (or equivalent product). Then the supernatant was diluted with freshly boiled water to the relative density of 1.254.
   (2) copper reagent liquid anhydrous disodium hydrogen phosphate 28g and potassium sodium tartrate (KNaC4H4O6 4H2O) 40g dissolved in 700ml of water. Added 1mol / L sodium hydroxide 100 ml, 8 g of copper sulfate pentahydrate, coupled over anhydrous sodium sulfate, 180g. Potassium iodate 0.7134g, and then diluted to 1000 ml. The solution was allowed to stand for a few days later, at the top of the supernatant through a medium porosity sintered glass funnel and the filter.
   (3) glucose standard solution Accurately weigh of dried glucose (140 mg) was dissolved in 500 ml of water.
   (4) Disodium hydrogen phosphate solution was taken heptahydrate disodium hydrogen phosphate, 19g, was dissolved in 100 ml of water.
   (5) The operation was accurately weighed and the sample 1g, dissolved in i50ml water, and the pH value was adjusted to 6.9 ~ 7.2 with sodium hydroxide or acetic acid. Gradually adding basic lead acetate solution, to no longer feel progress = step precipitation occurs. Add water to 250.0 Mix well: the mixture was centrifuged; draw 10 ml of the supernatant was transferred to a 50 ml volumetric flask, and then diluted to approximately 35rnl. Plus disodium hydrogen phosphate solution 2ml or more ¯ to no longer precipitate appears. Diluted to 50 ml with water and mix. Centrifuged at 2100 times gravity 10min. Draw 5 ml of the supernatant was placed in a test tube, add notes reagent solution 5ml, mixed. Loosely stuffed mouth of the tube will be placed in a boiling water bath for 40min ± 10s. After heating, the test tube immediately in cold water will cool. Plus 2.5% potassium iodide solution 2ml and 2 mol / L sulfuric acid 1.5ml. Thoroughly mixed with 0.005 mol / L sodium thiosulfate, using starch indicator, record the consumption volume of anger. Glucose standard solution (glucose standard the liquid 5rnl plus copper reagent 5ml) repeat the above operation, recording the consumption volume for ‰. Above each titration with 5 ml of water and bml copper reagent solution as a blank, blank titration, set the consumption volume for ‰.
   4.50% viscosity of the sample solution Accurately weigh to dry the base of the specimen 200g, dissolved in 200 ml of water served in a 500ml beaker. The solution was then equilibrated at 25 ° C under a Brookfield viscometer A (LVG, or equivalent product), using a No. 2 rotor under 20r/min Determination of the viscosity of the solution.

How to analyze calcium lignosulfonate