GB/T 5537-1985 Vegetable oils and fats - Determination of phospholipids

GB/T 5537-1985 Vegetable oils and fats - Determination of phospholipids GB/T5537-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Inspection of vegetable oils
Methods for determination of phosphatideGB/T5537—85
This standard applies to the determination of phosphatide in commercial vegetable oils. Phospholipids in oils are complex compounds composed of glycerol, fatty acids, phosphoric acid and amino alcohols. 1 Molybdenum blue colorimetric method
1.1 Apparatus and utensils
1.1.1 Porcelain crucible or quartz crucible;
1.1.2 Spectrophotometer or 50ml colorimetric tube with stopper;1.1.3 Pipette: 5, 10ml;
1.1.4 Electric furnace, high-temperature furnace;
1.1.5 Volumetric flask: 100, 500, 1000ml;1.1.6
Surface blood, beaker, measuring cylinder;
Constant temperature water bath;
Funnel, pliers, reagent bottle, etc.
1.2 Reagents
1.2.150% potassium hydroxide solution;
Hydrochloric acid, sulfuric acid, zinc oxide, filter paper;
1.2.30.015% hydrazine sulfate solution:bzxZ.net
1.2.4: 2.5% sodium molybdate dilute sulfuric acid solution: Measure 140ml sulfuric acid and inject it into 300ml water, shake it well, cool it to room temperature, add 12.5g sodium molybdate, add water to 500ml after dissolving, shake the spoon, and let it stand for 24h for use. 1.2.5 Phosphorus standard solution: Weigh 0.4391g of anhydrous potassium dihydrogen phosphate and dissolve it in 1000ml water as liquid No. 1, containing 0.1mg/ml phosphorus, absorb 10ml of liquid No. 1, add water to dilute it to 100ml, containing 0.01mg/ml phosphorus, as liquid No. 2, for colorimetry.
1.3 Operation method
1.3.1 Draw the standard curve: Take 5 50ml colorimetric tubes, number them 1, 2, 4, 6, 8, and inject 1, 2, 4, 6, 8ml of phosphorus standard No. 2 solution in the order of numbers, and then add 9, 8, 6, 4, 2ml of water in the order. Then add 8.0ml of 0.015% hydrazine sulfate solution to each of the 5 tubes; add 2.0ml of sodium molybdate dilute sulfuric acid solution to each, add stoppers, and shake well. Remove the stoppers, place the 5 tubes in a boiling water bath and heat for 10 minutes, take them out and cool to room temperature, dilute them with water to 50ml, shake them thoroughly for 10 minutes, and use a spectrophotometer at a wavelength of 650mm, use a 3cm liquid tank, adjust the zero point with water, and measure the digestion values ​​respectively. Draw a standard curve with digestion value as ordinate and phosphorus content (0.01, 0.02, 0.04, 0.06, 0.08 mg) as abscissa.
1.3.2 Prepare the test solution: weigh about 10g of the sample (accurate to 0.001g) in a crucible, add 0.5g of zinc oxide, heat it on an electric furnace for carbonization, and then send it into a high-temperature furnace at 550-600℃ to burn it until it turns to ashes (white). The burning time is about 2h, take it out and cool it to room temperature, dissolve the ash with 10ml of hot hydrochloric acid (1:1), and heat it to a slight boil for 5min, filter the solution and inject it into a 100ml volumetric flask, rinse the crucible and filter paper with hot water, wait for the filtrate to cool to room temperature, neutralize it with 50% potassium hydroxide solution until it becomes turbid, slowly add hydrochloric acid to dissolve all the zinc oxide precipitates, and then add 2 drops, finally dilute it to the scale with water and shake it well.
1.3.3 Colorimetry: Use a pipette to draw 10ml of the test solution into a 50ml colorimetric tube, add 8.0ml of 0.015% hydrazine sulfate and 2.0ml of sodium molybdate dilute sulfuric acid solution, add a stopper, and shake well. Remove the stopper, place the colorimetric tube in a boiling water bath and heat for 10 minutes, take it out and cool it to room temperature, dilute it with water to 50ml, shake it well, and after 10 minutes, use a spectrophotometer at a wavelength of 650nm, use a 3cm liquid tank, adjust the zero point with water, and measure the extinction value. 1.4 Calculation of results
According to the extinction value of the test liquid, the phosphorus content (P) is obtained from the standard curve, and the phospholipid content is calculated according to formula (1): V2
Phospholipid (%)=P×一×26.31×
Phosphorus content obtained from the standard curve, mg;
Wherein: P
-volume of sample diluted after ashing, ml;
-volume of the test liquid taken during colorimetry, ml; Vi
26.31mg of phosphorus is equivalent to mg of phospholipid; W——sample weight, g.
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The allowable difference between the two test results does not exceed 0.04%. The average is the test result. The test result is rounded to the second decimal place.
2 Gravimetric method
2.1 Apparatus and equipment
2.1.1 Glass funnel, funnel stand;
2.1.2 Beaker: 100ml;
2.1.3 Conical flask, filter paper, etc.
2.2 Reagents
Acetone.
2.3 Operation method
Take about 100ml of the mixed sample and filter it when heated to about 90℃. Weigh 25g of the sample in a beaker, heat it to 80℃, add 2-2.5ml of water, stir it thoroughly to hydrate it, let it stand overnight at room temperature, or centrifuge it, pour out the supernatant, filter it with a filter paper of known constant weight (or filter it with a vacuum device), and after all the filtrate is filtered out, use cold acetone to rinse the remaining precipitate in the cup into the filter paper, and continue to wash the filter paper and precipitate with acetone until there is no oil stain. After the acetone on the filter paper and the precipitate has evaporated, place them in a 105°C oven and dry until constant weight. 2.4 Result calculation
The phospholipid content is determined by the gravimetric method according to formula (2): Wi
Phospholipid (%)=×100
Wherein: W1—precipitate weight, g;
Sample weight, g.
....(2)
The allowable difference between the two test results shall not exceed 0.04%. The average is the measurement result. The measurement result is rounded to the second decimal place.
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, Wu Yanxia, ​​and Lv Guifen. Issued by the National Bureau of Standards on November 2, 1985
Implementation on July 1, 1986
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