GB 21034-2017Feed additive-Calcium salt of hydroxyl analogue of methionine (English PDF)

4.2 Identification test

4.2.1 Reagents and solutions Anhydrous copper sulfate saturated sulfuric acid solution. Take anhydrous copper sulfate by adding concentrated sulfuric acid until precipitation appears.

4.2.2 Amino acid identification method Weigh the sample 25mg in a dry test tube, add anhydrous copper sulfate saturated sulfuric acid solution (4.2.1) 1mL, the solution was immediately yellow, and then turn Into yellow-green.

4.2.3 methionine hydroxy analog qualitative identification

4.2.3.1 Reagents and solutions 4.2.3.1.1 Standard. Methionine hydroxy analog calcium salt standard (purity 99%). 4.2.3.1.2 methionine hydroxy analog calcium salt standard solution (100mg/L). Weigh methionine hydroxy analog calcium salt standard (4.2.3.1.1) 0.1g (accurate to 0.0001g), add water after ultrasonic solubilization volume to 100mL, take the solution 10mL, water volume to 100mL.

4.2.3.2 Identification method Weigh the sample 0.1g (accurate to 0.0001g), add water ultrasonic assisted solution volume to 100mL, take the solution 10mL, water to volume 100mL. According to GB/T 19371.2 determination, the sample solution of methionine hydroxy analog calcium salt solution peak retention time and methionine hydroxyl Analogues calcium salt standard solution (4.2.3.1.2) the same, and the hydroxy analog content >= 80%.

4.3 methionine hydroxy analog calcium salt and methionine hydroxy analog content determination

4.3.1 Reagents and materials

4.3.1.1 Acid solution. Glacial acetic acid. water. concentrated hydrochloric acid = 50 10 3.

4.3.1.2 potassium bromate - potassium bromide standard titration solution, c ( 6KBrO3 ) Is about

0.6 mol/L. Weigh 17.5g potassium bromate (accurate to 0.0001g) and 112.5g potassium bromide (accurate to 0.0001g), dissolved in water after the volume to 1L. According to GB/T 601 provisions of the method of calibration, this solution stored in a brown bottle, valid for one month.

4.3.2 Equipment

4.3.2.1 automatic potentiometer or pH meter.

4.3.2.2 platinum saturated calomel electrode composite electrode.

4.3.3 Analysis method

4.3.3.1 Principle In acidic media, methionine hydroxy analogues undergo the following redox reactions. 3RSR 'BrO-3 -> 3RSOR' Br- In the test solution into a platinum saturated calomel electrode composed of composite electrode (or Pt saturated calomel composite electrode), with the titration The addition of liquid, the concentration of ions to be tested constantly changing, the electrode potential also occurred in the corresponding changes occur at the equivalence point potential over, in order to determine the titration end.

4.3.3.2 Procedure Weigh 0.5g (accurate to 0.0001g) crushed, dried (105 °C ± 2 °C) to a constant weight of the sample in a 150mL beaker, add 50mL acid solution (4.3.1.1), ultrasonic dissolved beaker set magnetic stirrer, the electrode into the solution, adjust the stirring speed to the solution Fully vortex, potassium bromate - potassium bromide standard titration solution (4.3.1.2) titration, according to GB/T 9725, confirm the titration volume.

4.3.4 Calculation Results Methionine hydroxy analog calcium salt [(CH3SCH2CH2CHOHCOO) 2Ca] content X1 mass fraction, the value is expressed in% According to equation (1) calculation. X1 = c1 × V1 × 0.0846 m1 × 100 (1) In the formula. c1

--- potassium bromate - potassium bromide standard titration solution concentration in units of moles per liter (mol/L); V1

--- titration sample consumed potassium bromate - potassium bromide standard titration solution volume, in milliliters (mL); 0.0846

--- and 1.0mL potassium bromate - potassium bromide standard titration solution [c ( 6KBrO3 ) = 1.0mol/L] equivalent, in grams The methionine hydroxy analog calcium salt mass; m1

--- sample quality, in grams (g). Methionine hydroxy analog [CH3SCH2CH2CHOHCOOH] Content X2 in terms of mass fraction, the value is expressed in%, according to equation (2) Calculate. X2 = c1 × V1 × 0.0751 m1 × 100 (2) In the formula. c1

--- potassium bromate - potassium bromide standard titration solution concentration in units of moles per liter (mol/L); V1

--- titration sample consumed potassium bromate - potassium bromide standard titration solution volume, in milliliters (mL); 0.0751

--- and 1.0mL potassium bromate - potassium bromide standard titration solution [c ( 6KBrO3 ) = 1.0mol/L] equivalent, in grams Of methionine hydroxy analogues; m1

--- sample quality, in grams (g). Take two parallel determination of the arithmetic mean measurement results. The result is one decimal place.

4.3.5 Repeatability The absolute difference between two parallel determination results is not more than 0.2%.

4.4 Determination of loss on drying According to GB/T 6435 determination.

4.5 Determination of calcium According to GB/T 6436 determination.

4.6.1 Reagents and solutions

4.6.1.1 Sulfuric acid. Note that sulfuric acid is a strong corrosive liquid, the operator should wear safety goggles and gloves to prevent burns.

4.6.1.2 Nitric acid.

4.6.1.3 Hydrochloric acid.

4.6.1.4 Lead standard solution .1000µg/mL.

4.6.1.5 Sodium hydroxide solution .40g/L.

4.6.1.6 Ammonia solution (10%) Prepared according to GB/T 603

4.6.1.7 hydrochloric acid solution I Take hydrochloric acid 63mL, add water to make 100mL, shake.

4.6.1.8 hydrochloric acid solution II. Take hydrochloric acid 18mL, add water to make 100mL, shake.

4.6.1.9 thioacetamide solution Take thioacetamide 4g, add water to dissolve into 100mL, set the refrigerator for storage. Pro use before

1.0 mL and a mixed solution [consisting of 15 mL of sodium hydroxide solution (4.6.1.5),

5.0 mL of water and 20 mL of glycerol] were placed in a water bath Heat 20s, mix well, cool and use immediately.

4.6.1.10 Acetate buffer (pH 3.5) Take 25g of ammonium acetate and add 25mL of water to dissolve. Add 38mL of hydrochloric acid solution I (4.6.1.7) Acid solution II (4.6.1.8) or ammonia solution (4.6.1.6) accurately adjust the pH to 3.5 (potentiometer instructions), diluted with water to 100mL, Shake well.

4.6.1.11 phenolphthalein indicator solution. Prepared according to GB/T 603.

4.6.1.12 Preparation of lead standard working solution Amount of lead standard solution (4.6.1.4) 2.00mL, set.200mL flask, diluted with water to the mark, Shake well (equivalent to 10 µg of Pb per ml).

4.6.2 Analysis steps

4.6.2.1 Preparation of sample solution Weigh the sample 1g (accurate to 0.01g), home porcelain crucible, slowly burning to fully carbonized, let cool. Add sulfuric acid (4.6.1.1) 0.5mL ~ 1mL humid, low temperature heating to sulfuric acid vapor removed, the ignition at 550 °C completely ashed, let cool. Add nitric acid (4.6.1.2) 0.5mL, Steam dry until the nitrogen oxide vapor removed, let it cool. Add hydrochloric acid (4.6.1.3) 2.0mL, water bath and add water 15mL, ammonia solution was added dropwise (4.6.1.6) to phenolphthalein indicator solution (4.6.1.11) was reddish, coupled with acetate buffer (4.6.1.10) 2.0mL, after the solution was slightly dissolved, the displacement Nessler colorimetric tube, diluted with water into 25mL, as B tube.

4.6.2.2 Preparation of standard colorimetric solution Another preparation of sample solution reagents, home-made porcelain crucible evaporated, add acetate buffer (4.6.1.10) 2.0mL and water 15mL, micro After thermal dissolution, remove the Nessler colorimetric tube, add 2.0mL of standard working solution (4.6.1.12) of lead and dilute it with water to 25mL as a tube.

4.6.3 determine the result In A, B two were added thioacetamide solution (4.6.1.9) each 2.0mL, shake, place 2min, with the same white paper, from the top to Under the perspective of observation and comparison of the color of the tube A and B, such as the color of the tube was not deeper than the A tube, then judged to comply with the provisions.

4.7 Determination of total arsenic According to GB/T 13079 determination.

5 inspection rules

5.1 group approved With the same raw materials, the same production process, continuous production or the same batch of products produced for a group.

5.2 Sampling methods According to GB/T 14699.1.

5.3 factory inspection Appearance and traits, methionine hydroxy analog content, loss on drying, total arsenic, heavy metals for the factory inspection items.

5.4 type test Type test items for the provisions of Chapter 3 of all projects. Product normal production, at least once every six months type test, but there When one of the cases is listed, type tests are also conducted.

a) When the production process and equipment have major changes;

b) when there is a significant change in the raw materials used;

c) stop production for more than three months to resume production;

d) the factory test results and the last type test results are quite different.

5.5 determine the method Inspection results have an indicator does not meet the requirements of this standard, should be re-sampled twice from the amount of packaging reinspection, retest results even There is an indicator does not meet the requirements of this standard, the entire batch of products is unqualified. 6 labels, packaging, transportation, storage