This standard specifies the determination method of minerals and trace elements in compound feeds for experimental animals, namely the determination method of iron, copper, manganese, zinc, magnesium, sodium, potassium, selenium and iodine. This standard is applicable to the determination of iron, copper, manganese, zinc, magnesium, sodium, potassium, selenium and iodine in compound feeds and raw materials for experimental animals such as mice, rats, rabbits, guinea pigs, hamsters, dogs and monkeys. GB/T 14924.12-2001 Determination of minerals and trace elements in compound feeds for experimental animals GB/T14924.12-2001 Standard download decompression password: www.bzxz.net

GB/T14924.12--2001
All technical contents of this standard are recommended.
This standard is separated from GB14924-1994 "Complete Nutrient Feed for Laboratory Animals" to form an independent standard. After fully demonstrating the "4 Test Methods" in GB14924-1994 "Complete Nutrient Feed for Laboratory Animals", this standard revises the determination methods of minerals and trace elements in compound feeds, namely the determination methods of iron, copper, manganese, zinc, and magnesium in compound feeds and the determination methods of potassium and sodium in compound feeds (the methods supplemented in this revision), selenium (the methods supplemented in this revision), and iodine (the newly added method).
This standard and its supporting standards shall replace GB14924-1994 from the date of implementation. This standard Proposed and managed by the Ministry of Science and Technology of the People's Republic of China. Drafting unit of this standard: China Laboratory Animal Society. Main drafters of this standard: Zhou Ruihua, Men Jianhua, Wang Guangya, Zheng Tao, Zhang Yu, Liu Yuan, Liu Xiumei. This standard is entrusted by the Ministry of Science and Technology to the China Laboratory Animal Society for interpretation. This standard was first issued in January 1994.
1 Scope
National Standard of the People's Republic of China
Laboratory animals-Formula feeds-Determination of minerals and trace elementsGB/T14924. 12--.2001
Replaces GB119211991
This standard specifies the determination method of minerals and trace elements in experimental animal compound feeds, namely the determination method of iron, copper, manganese, zinc, magnesium, sodium, potassium, selenium and iodine.
This standard is applicable to the determination of iron, copper, manganese, zinc, magnesium, sodium, potassium, selenium and iodine in compound feeds and raw materials for experimental animals such as mice, rats, rabbits, guinea pigs, hamsters, dogs and monkeys.
2 Reference Standards
|The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T5009.13—1996 Determination of copper in food GB/T5009.14--1996 Determination of zinc in food GB/T12396-1990 Determination of iron, magnesium and manganese in food GB/T GB/T 12397-1990
）Determination of potassium and sodium in food
3Determination of selenium in food
GB/T 12399--.-1996
GB/T 13883-1992
2Determination of selenium in feed 2.3-Diaminonaphthalene fluorescence method GB/T 13885-1992
Determination of iron, copper, manganese, zinc and magnesium in feed Atomic absorption spectrometry 3 Determination method
3.1 The determination of iron, copper, manganese, zinc and magnesium in compound feed shall be carried out in accordance with the relevant provisions of GI3/T13885, GB/T12396, GB/T5009.13 and GB/T5009.14. 3.2 The determination of potassium and sodium in compound feed shall be carried out in accordance with the provisions of GB/T12397.
3.3 Determination of selenium in compound feed
According to the relevant provisions of GB/T12399 and GB/T13883. 3.4 Determination of iodine in compound feed
3.4.1 Principle
The arsenic-arsenic contact method is to determine the iodine content by utilizing the catalytic effect of iodine on the redox reaction of arsenous acid and cerium sulfate in an acidic environment: 2Ce 4+H.As +30: +H20→2Ce t3-+H3As +5042Cet++21 -2Ce*3+12
Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on 2001-08-29 and implemented on 2002-05-01
GB/T 14924.122001
I2+As 3-21 +As*
Since (e oxidizes iodine ions to elemental iodine, and elemental iodine is reduced to iodine ions by As, and this is repeated until AsCe is completely consumed, when the reaction conditions are controlled, the reaction rate and the iodine ion concentration have a certain numerical relationship. The more iodine ions there are, the faster the reaction rate. The colorimetric quantitative analysis is performed based on the degree of fading of sulfuric acid to determine the iodine content. The minimum detection limit of this method is (.0011g3.4.2 Reagents
The reagents used in this test are of analytical grade or above, and the water is deionized water with a resistivity of more than 2 million ohms. 3.4.2.1 Zinc sulfate (0.44mol/L): Weigh 100g zinc sulfate and dissolve it in a small amount of water. After it is completely dissolved, move it into a volumetric flask 11. and dilute it to the scale with water.
3.4.2.2 Sodium hydroxide (0.5mol/L): Weigh 20g sodium hydroxide and dissolve it in a small amount of water. , after it is completely dissolved, transfer it to a volumetric flask and dilute it to the mark with water.
3.4.2.3 Potassium carbonate solution (2.17mol/L): weigh 30g potassium carbonate and dissolve it in a small amount of water. After it is completely dissolved, transfer it to a 100ml volumetric flask and dilute it to the mark with water.
3.4.2.4 Arsenic acid solution (0.005mol/l.): accurately weigh 0.986g arsenic trioxide and dissolve it in a warm Heat 15ml.0.5mol/l sodium nitride, add this solution to 850ml water. Add 39.6mL of high-grade concentrated sulfuric acid and 20ml of concentrated hydrochloric acid. After cooling, transfer to a 1I volumetric flask and add water to 1000ml.
3.4.2.5 Cerium sulfate (0.02mol/L): Weigh 8.087g of cerium sulfate, dissolve it in deionized water, add 44ml of high-grade concentrated sulfuric acid. After cooling, dilute to 1000ml. mL.
3.4.2.6 Iodine standard solution:
3.4.2.6.1 Iodine standard stock solution (0.1mg/mL): Accurately weigh 0.1686g of potassium iodate dried to constant weight at 110°C, dissolve it in a small amount of water, transfer it to a volumetric flask, and dilute it to 1000mL. 3.4.2.6.2 Iodine standard intermediate solution (1,μg/mL): Accurately pipette 1ml. (3.6.1) solution and dilute it to 100mlL. 3.4.2.6.3 Iodine standard application solution (0.1μg/mL): Accurately pipette 1ml. (3.6.2) solution and dilute it to 10ml. Prepare it when needed. 3.4.2.7 Sodium chloride (4.4mol/L): Weigh 26g of high-grade pure sodium chloride, dissolve it and dilute it to 100mL. 3.4.3 Instruments and equipment
3.4.3.1 Super constant temperature water bath.
3.4.3.2 Muffle furnace.
3.4.3.3 Oven.
3.4.3.4 Centrifuge.
3.4.3.5 Stopwatch.
3.4.3.6 Spectrophotometer.
3.4.3.7 Crucible.
3.4.4 Operation steps
3.4.4.1 Weigh an appropriate amount of sample and put it into a crucible, add 0.5 ml of 0.44 mol/L zinc sulfate and 0.5 ml of 2.17 mol/L potassium carbonate, mix well, leave for 1 hour, and then place in a 110℃ oven for 14 to 16 hours until completely dry. 3.4.4.2 Place the crucible in an ashing furnace at 550°C for 4-8 hours. After ashing, the sample must be free of obvious carbon particles and grayish white. If there are still carbon particles, add two drops of water and bake in an oven at 110°C for a second ashing until it is grayish white. 3.4.4.3 Add 5 mL of arsenic acid solution to dissolve the sample in the crucible. The solution should be free of carbon particles. Transfer the liquid into a centrifuge tube and centrifuge at 3000 r/min for 5 minutes. Take the supernatant. 3.4.4.4 Add 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mL of iodine standard application solution to 6 standard series tubes in sequence, equivalent to 0, 0.02, 0.04, 0.06, 0.08, and 0.10 μg of iodine. Add an appropriate amount of sample solution to the sample tube, add arsenite solution to the standard tube and sample tube respectively, so that the total volume of the solution in the tube is 5ml, and then add 0.5mL of 4.44mol/l sodium chloride. 3.4.4.5 After shaking the above tubes, place them in a (32±0.2)℃ constant temperature water bath, and at the same time add 0.02mol/L arsenic sulfate solution and keep warm for 10min.
GB/T 14924.12--2001
3.4.4.6 Add 0.5ml.0.0.02mol/L, add antimony sulfate to the test tube, shake quickly, put it in a water bath, and compare the color of one tube every 30s after 15 minutes after the first addition of antimony sulfate solution. The wavelength of the spectrophotometer is 410nm for colorimetry. Use deionized water to adjust the instrument zero point and measure the absorbance values ​​of the standard series tubes and sample tubes. 3.4.5 Calculation
According to the reaction principle. In the reaction, the catalytic effect of iodine ions is proportional to the iodide content, which is a straight line in the semi-logarithmic coordinate. Therefore, the standard curve regression method is used to calculate and analyze the results in the calculation of the analysis results. The curve should be linearized before regression. The linear regression equation is obtained by taking the logarithm of the iodine concentration and the corresponding absorbance value, and the iodine content of each test tube is found according to the logarithm of the sample absorbance value, see formula (1). logY =- Bc + loga
武fl; logY
the logarithmic value of the absorbance of the measured sample;
-the iodine content in the measured sample tube, g;
B-the slope of the curve;
logA-the intercept of the curve.
Calculate the iodine concentration in the sample according to formula (2): J×(cc)
Formula 4: Xwww.bzxz.net
the iodine concentration in the measured sample, μg/100g; the iodine content in the measured sample tube, ug;
o——the iodine content of the reagent blank solution, μg;-dilution multiple;
sample mass, g.
3.4.6 Allowable error of the result
The relative deviation of the results of parallel or repeated measurements in the same laboratory is ≤10%. .+(1)
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