This standard specifies the acetrione colorimetric method for the determination of amino acid content in cosmetics. This standard is applicable to the determination of protein and its hydrolyzate, and amino acid content in cosmetics. The minimum detection concentration of this method is 0.01%. QB/T 2409-1998 Determination of amino acid content in cosmetics QB/T2409-1998 Standard download decompression password: www.bzxz.net

QB/T2409--1998
This standard is prepared in accordance with GB/T1.1-1993 "Basic Provisions for the Preparation of Standardization Guidelines". Introduction
Unit 1: Rules for the Drafting and Presentation of Standards Part 1: Standards
This standard is formulated based on the principle of colorimetric quantification of amino acids reacting with benzyltrione to generate blue-purple compounds under certain pH conditions.
This standard is proposed by the Industry Management Department of the State Bureau of Light Industry. This standard is under the jurisdiction of the National Cosmetics Standardization Center. The drafting unit of this standard: Shanghai Daily Chemical Industry Research Institute. The main drafters of this standard: Gan Pingping, Kong Jiahua, Pan Haiyan, Tang Zhiling. 108
1 Scope
Light Industry Industry Standard of the People's Republic of China
Determination of Amino Acid Content in Cosmetics
This standard specifies the benzyltrione colorimetric determination method for amino acid content in cosmetics. This standard is applicable to the determination of protein and its hydrolyzate and amino acid content in cosmetics. The minimum detection concentration of this method is 0.01%. 2 Reference standards
QB/T 2409-—1998
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 are subject to revision, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T8170-1987 Numerical rounding rules
3 Principle
Protein substances are hydrolyzed into amino acids, and the amino acids react with triketones under certain pH conditions to form blue-purple compounds, which are quantitatively determined by colorimetry to calculate the corresponding amino acid content. 4 Reagents
Analytical grade (AR) reagents should be used in the analysis, and the test water should be distilled water or water of equivalent purity. 4. 1 2% triketone solution
Weigh 1.0g of benzyltriketone (HG3-984), dissolve it in a certain amount of hot water, and dilute it to 50ml after cooling. This solution needs to be re-prepared every (2-3) days.
4.2 Phosphate buffer solution (pH=8.04) 4.2.1 1/15mol/L potassium dihydrogen phosphate solution Weigh 9.070g of potassium dihydrogen phosphate (GB/T 1274), dissolve it in water and dilute it to 1L. 4.2.2 1/15mol/L disodium hydrogen phosphate solution Weigh 23.876g of disodium hydrogen phosphate (GB/T1263), dissolve it in water and dilute it to 1L. 4.2.3 Take 5.0mL of solution 4.2.1 in a 100mL volumetric flask, dilute to the mark with solution 4.2.2, and shake well. 4.3 Hydrochloric acid (GB/T622) 6 mol/L solution
4.4 Amino acid standard solution (200μg/mL) Accurately weigh 0.2000g of leucine (L-Leucine content is not less than 98%), dissolve it in water and dilute it to 100ml, shake it and then draw 10mL into a 100mL volumetric flask and dilute it to the scale with water. 4.5 Wax block
The ratio of beeswax to paraffin is 1:9.
5 Instruments
5.1 Spectrophotometer: wavelength range 400nm～700nm. Approved by the State Bureau of Light Industry on November 25, 1998
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Implementation on June 1, 1999
5.2 Acidometer: graduation value 0.02.
5.3 Electromagnetic stirrer.
Volume flask: 100, 1000mL
Pipette: 1, 2, 5, 10mL.
5.6 Water bath.
Test tube: 30mm×200mm.
5.8 Analytical balance: graduation value 0.0001g. 5.9 Graduated test tube: 25, 100mL.
Beaker: 100ml.
6 Determination steps
6.1 Drawing of standard curve
QB/T 2409--1998
Accurately pipette 0.0, 0.2, 0.4, 0.6, 0.8, 1.0mL of amino acid standard solution (equivalent to 0, 40, 80120, 160, 200μg of amino acid) into 25mL graduated test tubes, add water to make up to 4mL, then add 1mL of 2% benzyltrione solution and phosphate buffer solution, shake well. Heat in a boiling water bath for 15min, take out and cool to room temperature, add water to the scale, shake well. Let stand for 15min, use a spectrophotometer at a wavelength of 570nm with water as reference, use 1cm colorimetric blood to determine the absorbance of the test solution, and draw a standard curve of absorbance versus amino acid content (μg). 6.2 Sample pretreatment
Accurately weigh about 5g of sample (accurate to 0.001g) into a test tube, add about 10ml~~20mL of 6mol/L hydrochloric acid solution and hydrolyze in a boiling water bath for about 6h (for emulsions, the sample can be placed in a boiling water bath to break the emulsion for 1h~2h). After adding about 1g~2g of wax block for about 30min, take out the test tube and cool it. Remove the wax block, transfer the solution to a 100mL beaker, adjust the pH to 7.5~8.0 with alkali solution on the acidometer, then transfer the solution to a 100mL volumetric flask and dilute to the scale with water, shake well and set aside. 6.3 Determination
Transfer 1mL~4mL of the test solution (6.2) into a 25mL graduated test tube, and proceed according to the determination steps in 6.1. Measure the absorbance, calculate the amino acid content through the standard curve, and make a blank sample at the same time. Results capsule
Amino acid content in the sample (in terms of leucine) was calculated according to formula (1): (C/-C.) X 100/V
Amino acid content (%) =
mX10°
Where: C—the amount of amino acids in the sample obtained from the standard curve, g; Co
the value of the blank sample obtained from the standard curve, ug; -the amount of sample solution transferred, mL;
—the amount of sample·g. bzxz.net
The obtained results were rounded to two decimal places according to GB/T8170. 8 Precision
The difference between the results of two parallel determinations should not be greater than 10% of their average value. 110
(1))
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