This standard is applicable to the determination of sand content in powdered grains. GB/T 5508-1985 Grain and oilseed inspection method for determination of sand content in powdered grains GB/T5508-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Inspection of grain and oilseeds
Methods for determination of sand content of flours
Inspection of grain and oilseedsMethods for determination of sand content of floursThis standard applies to the determination of sand content of commercial grain powder. 1 Carbon tetrachloride method
1.1 Apparatus and utensils
1.1.1 Fine sand separation funnel, funnel stand,
1.1.2 Balance: sensitivity 0.001g
1.1.3 Measuring cylinder: 10ml,
1.1.4 Electric furnace: 500W,
1.1.5 Desiccator with color-changing silica gel,
1.1.6 or aluminum box;
1.1.7 Reagent bottle: 1000ml;
1.1.8 Glass rod, asbestos net, etc.
1.2 Reagents
Carbon tetranitride.
1.3 Operation method
UDC (633.1+633.85)
.001.4
GB5508—85
Measure 70ml of carbon tetrachloride and inject it into the fine sand separation funnel, add 10g (W) of sample, stir gently three times (stir once every 5 minutes, and the glass rod should stir in the middle and upper part of the funnel), let it stand for 20 to 30 minutes, take out the flour floating on the surface with a corner spoon, and then put the carbon tetrafluoride and mud sand in the spherical shape of the separation funnel into a 20-cup crucible of known weight (W.), then rinse the sphere with carbon tetrachloride and twice, pour out the carbon tetrachloride in the crucible, dry it on an electric furnace with asbestos net, put it into a dryer, cool and weigh it (W,). 1.4 Calculation of results
Sand content is calculated according to formula (1):
W,--weight of crucible and fine sand, g;
W. weight, g,
W——weight of sample, g. www.bzxz.net
Sand content (%) = WW×100
The allowable difference between the two test results shall not exceed 0.005%, and the test result with the highest content shall be the test result. The test result shall be rounded to the second decimal place. 2 Ashing method
2.1 Apparatus and tools
2.1.1 Electric constant temperature water bath;
2.1.2 Ash-free filter paper;
2.1.3 High temperature electric furnace;
Promulgated by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 1986
2.1.4 Analytical balance: sensitivity 0.001g;
2.1.5 Porcelain: 18~20ml,
2.1.6 Desiccator equipped with color-changing silica gel;
2.1.7 Pliers: long handle and short handle.
2.2 Reagents
GB5508-85
2.2.110% hydrochloric acid: Take 237ml of concentrated hydrochloric acid with a specific gravity of 1.19, inject it into distilled water, then transfer it into a 11 volumetric flask and dilute it to 11, shake it well.
2.2.23% silver nitrate solution: Weigh 3g of silver nitrate and dissolve it in distilled water, add two drops of concentrated nitric acid to acidify it, then dilute it with distilled water to 100ml in a brown bottle, shake it well. 2.3 Operation method
Use a crucible with known constant weight to weigh 5g (W) of the sample, and ash it according to the method specified in GB5505-85 "Determination of ash content in grain and oil inspection". Dissolve the ash in the crucible in 10ml 10% hydrochloric acid, heat it in a water bath at about 80℃ for 5min, filter the solution with ash-free filter paper, wash the remaining insoluble residue in the crucible with 10ml hydrochloric acid twice, filter the solution and the residue with the original filter paper, and then wash the slag and filter paper with distilled water until the filtrate does not contain chloride ions (no turbidity after adding 3% silver nitrate solution). Dry the filter paper and precipitate and place them in a crucible with known weight (W.) for carbonization. After carbonization, burn it at 600℃ for 30min, cool it, weigh it, and bake it again for 20min until the weight is constant (W).
2.4 Calculation of results
The sand content is calculated according to formula (2):
Sand content (%)
Where: W, W., W are the same as 1.4.
The allowable difference and number of decimal places of double test results are the same as 1.4. Additional remarks:
This standard is proposed by the Ministry of Commerce of the People's Republic of China. This standard is drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. W,-W. ×100
The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia and Lv Guifen. (2)
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