GB/T 5527-1985 Determination of refractive index for inspection of vegetable oils and fats

This standard is applicable to the determination of the refractive index of commercial vegetable oils and fats. GB/T 5527-1985 Determination of the refractive index of vegetable oils and fats GB/T5527-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Inspection of vegetable oilsMethods for determination of refractive index
This standard applies to the determination of the refractive index of commercial vegetable oils. Instruments and appliances
1.1 Abbe refractometer:wwW.bzxz.Net
1.2 Small beaker;
1.3 Glass rod: one end is burned into a round shape
1.4 Lens paper, tweezers, absorbent cotton, etc.
2 Reagents
2.1 Ether;
2.2 Ethanol.
3 Operation method
GB/T 5527-85
3.1 Calibration of the instrument: Lay the instrument flat, clean the upper and lower prisms with absorbent cotton dipped in ether, and insert the thermometer into the thermometer seat. The instrument is calibrated with a material of known refractive index, usually pure water or α-bromonaphthalene or a standard glass slide. If the refractive index does not match the calibration material, use a small key to turn the small screw under the eyepiece to adjust the light-dark dividing line to be tangent to the intersection of the cross lines. 3.2 Determination: Use a round-headed glass rod to take two drops of the mixed and filtered sample and drop them on the prism (the glass rod should not touch the mirror surface), turn the upper prism, close the two prisms, and wait for about 3 minutes for the sample temperature to stabilize. Turn the Amisi prism handwheel and the prism rotation handwheel to divide the field of view into two clearly visible light and dark parts, with the dividing line just at the focus of the cross, and record the scale reading and temperature.
4 Result calculation
The scale reading is the refractive index value under the measurement temperature conditions. If the measurement temperature is not at 20℃, it must be converted to the refractive index at 20℃ (n20) according to the following formula. Refractive index (n20)
)=nt+0.00038×(t-20)
Wherein: nt is the refractive index measured when the oil temperature is t℃: - the oil temperature when the refractive index is measured;
0.00038 is the correction coefficient of the refractive index for every 1℃ difference in oil temperature between 10 and 30℃. Additional notes:
This standard was proposed by the Ministry of Commerce of the People's Republic of China. This standard was drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Hao Yanxia, ​​and Chang Guifen. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 1986
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