GB 36897-2018Feed additive - L-Arginine (English PDF)

4.1 Appearance and properties

The product is a white crystal or crystalline powder, almost odourless, with a characteristic taste.

The product is readily soluble in water, almost insoluble in ethanol, and readily soluble in dilute hydrochloric acid.

4.2 Technical requirements

The technical indicators shall comply with the requirements of Table 1.

Table 1 fixes nine indicators: the L-arginine content on a dry basis, the specific rotation, the clarity and colour of the solution, the pH, the chloride content as chlorine, the heavy metals content as lead, the total arsenic content, the loss on drying and the residue on ignition.

5.1 Appearance and properties

A suitable quantity of the sample is placed in a clean, dry white porcelain dish and its colour and physical state are observed, and its odour noted, in natural light.

5.2 Identification test

The identification is made by infrared spectrometry: the sample is ground with spectroscopically pure potassium bromide and pressed into a disc, its infrared spectrum is recorded, and that spectrum shall agree with the spectrum of the reference substance (the spectrum is given for information in Annex A).

5.3 Determination of the L-arginine content

The content is determined by non-aqueous titration: the sample is dissolved in anhydrous formic acid and glacial acetic acid, crystal violet is used as the indicator, and the solution is titrated with perchloric acid standard volumetric solution until the colour changes from blue to green, a blank test being carried out by the same method.

The L-arginine content on a dry basis is calculated by Formula (1) from the volumes of titrant consumed by the sample and by the blank, the concentration of the titrant, the mass of the sample and the moisture content of the sample. The result is taken as the arithmetic mean of parallel determinations.

5.4 Determination of the specific rotation

The instrument is calibrated before each determination using hydrochloric acid solution as the blank solvent. The sample, dried to constant mass, is dissolved in hydrochloric acid solution and made up to volume, the temperature of the solution is brought to equilibrium, and the rotation of the sample solution is read on a polarimeter, the mean of three readings being taken.

The specific rotation is calculated by Formula (2) from the measured angle of rotation, the length of the polarimeter tube and the mass concentration of L-arginine in the solution.

5.5 Determination of the clarity and the colour

The sample is dissolved in water. Using water as the reference, the clarity of the solution is observed against a black background and its colour against a white background.

5.6 Determination of the pH

The sample is dissolved in water and the pH is measured with a pH meter of the measuring range and precision specified in the standard.

5.7 Determination of the chloride

The sample solution and the standard solution are prepared in Nessler tubes with nitric acid solution. Silver nitrate solution is added to each, they are diluted, mixed and left in the dark, and are then viewed from above against a black background: the turbidity of the sample solution shall not be greater than that of the standard solution.

5.8 Determination of the heavy metals as lead

The test solution is prepared from the sample with acetate buffer solution in a Nessler tube. Three Nessler tubes are set up - one with the standard lead solution, one with the sample, and one with the sample together with the standard lead solution - thioacetamide test solution is added to each, and the colours are compared by viewing from above against white paper.

5.9 Determination of the arsenic

The determination uses the arsenic-testing apparatus shown in Figure 1, made up of a standard ground-neck conical flask, a hollow standard ground stopper, a gas-conducting tube, a perforated organic glass screw stopper and an organic glass screw cap.

Lead acetate cotton is packed into the gas-conducting tube and a mercuric bromide test paper is fitted, a standard arsenic stain is prepared from the standard arsenic solution, and the sample is then treated by the same procedure; the arsenic stain produced by the sample shall not be deeper than the standard stain.

5.10 Determination of the loss on drying

Carried out according to the direct drying method of 8.1 of GB/T 6435-2014.

5.11 Determination of the residue on ignition

Carried out according to GB/T 6438 Animal feeding stuffs - Determination of crude ash.

6.1 Batching

Products of the same material, made by the same production process, produced continuously or in the same shift, form one batch; the mass of each batch shall not exceed the limit given in the standard.

6.2 Sampling

Carried out according to GB/T 14699.1.

6.3 Factory inspection

The factory inspection items are the appearance and properties, the L-arginine content on a dry basis, the pH, the moisture, and the heavy metals as lead.

6.4 Type inspection

The type inspection items are all the items specified in Clause 4. Under normal production conditions a type inspection is carried out at least once every half year. A type inspection shall also be carried out in any of the following circumstances: a) when the product is finalised and put into production; b) when the production process, the formula or the source of the main raw material changes appreciably in a way that may affect the quality of the product; c) when production is resumed after having been stopped for three months or more; d) when the result of a factory inspection differs appreciably from the result of the previous type inspection; e) when the feed administration department requires an inspection.

6.5 Judgement rules

Where any indicator does not meet the requirements of this standard, samples may be drawn from double the quantity of packages for re-inspection. If, in the result of the re-inspection, even one indicator fails to meet the requirements of the standard, that batch of product is judged non-conforming.

7.1 Label

The label is made out according to GB 10648, and the name of the production process is stated on it.

7.2 Packaging

The packaging material shall be clean and hygienic and shall protect against contamination, against damp and against leakage.

7.3 Transport

The means of transport shall be clean and hygienic and shall protect against strong sunlight and against rain; the product shall not be carried together with toxic or harmful substances.

7.4 Storage

The product is stored in a ventilated, dry place protected from strong sunlight and from rain, with facilities against insects and rodents; it shall not be stored together with toxic or harmful substances.

7.5 Shelf life

Under the specified conditions of transport and storage, the shelf life of a sample in an unopened package is the period given in the standard.