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GB 5009.43-2016 English PDF (GB5009.43-2016)

GB 5009.43-2016 English PDF (GB5009.43-2016)

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GB 5009.43-2016: National Food Safety Standard -- Determination of sodium glutamate in monosodium glutamate

This Standard specifies the determination method for sodium glutamate in monosodium glutamate. This Standard is applicable to the determination of sodium glutamate in monosodium glutamate.
GB 5009.43-2016
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
National Food Safety Standard ?€? Determination of
sodium glutamate in monosodium glutamate
ISSUED ON. AUGUST 31, 2016
IMPLEMENTED ON. MARCH 1, 2017
Issued by. National Health and Family Planning Commission of the
PEOPLE Republic of China
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents and Materials ... 4
4 Instruments and Apparatus ... 5
5 Analysis Steps ... 5
6 Expression of Analysis Results ... 6
7 Precision ... 7
8 Principle ... 8
9 Reagents ... 8
10 Instruments and Apparatus ... 8
11 Analysis Steps ... 8
12 Expression of Analysis Results ... 9
13 Precision ... 9
14 Principle ... 10
15 Reagents and Materials ... 10
16 Instruments and Apparatus ... 10
17 Analysis Steps ... 10
18 Expression of Analysis Results ... 11
19 Precision ... 12
National Food Safety Standard ?€? Determination of
sodium glutamate in monosodium glutamate
1 Scope
This Standard specifies the determination method for sodium glutamate in monosodium glutamate.
This Standard is applicable to the determination of sodium glutamate in monosodium glutamate.
First method ?€? Titration method of perchloric acid non-
aqueous solution
2 Principle
In the presence of acetic acid, use perchloric acid standard solution to titrate the sodium glutamate in sample; treat the sudden jump of electric potential as the basis to determine the titration?€?s endpoint OR treat ??-Naphthol phenylmethanol as the indicator to titrate the sample solution until it turns to green ?€? that is the endpoint. 3 Reagents and Materials
Unless otherwise stated, the used reagents in this method shall all be analytical purity; the water shall be the Grade-2 water which is specified in GB/T 6682.
3.1 Reagents
3.1.1 Formic acid (CH2O2).
3.1.2 Acetic acid (C2H4O2).
3.1.3 ??-Naphthol phenylmethanol (C27H18O2).
3.2 Preparation for reagent
??-naphthol phenylmethanol-acetic acid indicator solution (2g/L). weigh and take 0.1g of ??-naphthol phenylmethanol; use acetic acid (3.1.2) to dissolve it; dilute it to 50mL. 3.3 Standard products
Perchloric acid (HClO4).
3.4 Preparation for standard solution
Perchloric acid standard titration solution [c(HClO4) = 0.1mol/L]. according to GB/T 601, prepare and calibrate it.
4 Instruments and Apparatus
4.1 Automatic potentiometric titrator (the accuracy shall be ?? 0.2mV) - with dynamic titration mode or equal titration mode. Minimum volume of liquid added shall be 0.01mL. The burette has anti-proliferation head.
4.2 Non-aqueous pH electrode regards Ag/AgCl as internal reference electrode; the internal reference electrolyte shall be 2mol/L lithium chloride ethanol solution OR 0.4mol/L tetraethylammonium bromide ethylene glycol solution.
4.3 Magnetic stirrer.
4.4 Analytical balance. the sensitivity is 0.1mg.
4.5 Ultrasonic cleaner.
5 Analysis Steps
5.1 Preparation for samples
Weigh and take 0.15g (accurate to 0.0001g) of the sample which has been ground into fine particles; place it into a 100mL beaker; add 3mL of formic acid (3.1.1); sonicate it until it is completely dissolved; then, add 40 mL of acetic acid (3.1.2); shake it evenly. 5.2 Determination of sample
5.2.1 Determination by potentiometric titration method
5.2.1.1 Reference conditions for the determination of sample.
a) The determination of sample adopts dynamic titration mode OR equal titration mode;
b) Blank determination of reagents. adopt equivalent titration mode. Minimum are obtained under repeatability conditions shall not exceed 0.5g/100g. Second Method ?€? Optical Rotation Method
8 Principle
Molecular structure of sodium glutamate contains an asymmetric carbon atom, which has optical activity and can rotate the polarized surface to certain angle. Therefore, polarimeter can be used to determine the optical rotation. The content of sodium glutamate can be converted according to the optical rotation.
9 Reagents
Unless otherwise stated, the used reagents in this method shall all be analytical purity; the water shall be the Grade-2 water which is specified in GB/T 6682.
Hydrochloric acid (HCl).
10 Instruments and Apparatus
10.1 Polarimeter (the accuracy shall be ?? 0.010??) shall be equipped with sodium lamp (sodium spectrum?€?s D-line shall be 589.3 nm).
10.2 Analytical balance. the sensitivity is 0.1mg.
11 Analysis Steps
11.1 Preparation for samples
Weigh and take 10g of the sample (accurate to 0.0001g); add small amount of water to dissolve it; transfer it to a 100mL volumetric flask; add 20mL of hydrochloric acid; mix it AND cool it to 20 ??C; set it to constant volume; shake it evenly. 11.2 Determination of sample solution
At 20??C, use the standard optical rotation angle to calibrate the instrument; place the test solution of 11.1 in the optical rotation tube (There shall be no air bubbles); observe its optical rotation; at the same time, record the temperature of the sample solution in optical rotation tube.
17.2 Determination of sample solution
Turn on the magnetic stirrer; use sodium-hydroxide standard solution to titrate until that the acidometer indicates ?€?pH 8.2?€?; record the milliliters of the consumed sodium- hydroxide standard titration solution; calculate the content of the total acid. Add 10.0 mL of formaldehyde solution; mix it evenly; use sodium-hydroxide standard solution to titrate until that the acidometer indicates ?€?pH 9.6?€?; record the milliliters of the consumed sodium-hydroxide standard titration solution.
Meanwhile, take 60mL of water; firstly, use sodium-hydroxide standard solution to adjust it to ?€?pH 8.2?€?; then, add 10.0mL of formaldehyde solution; use sodium hydroxide standard solution to titrate it until pH 9.6; make reagent?€?s blank test. 18 Expression of Analysis Results
In sample, the content of sodium glutamate (it contains 1 molecule of crystal water) shall be calculated according to formula (4).
X3 - In sample, the content of sodium glutamate (it contains 1 molecule of crystal water). The unit is grams per hundred grams (g/100g);
V1 ?€? For the used sample in measurement, after adding the formaldehyde, the consumed volume of sodium-hydroxide standard solution. The unit is milliliter (mL); V2 ?€? For reagent blank, after adding the formaldehyde, the consumed volume of sodium-hydroxide standard solution. The unit is milliliter (mL);
c - Concentration of sodium-hydroxide standard titration solution. The unit is mole per liter (mol/L);
0.187 - Mass of 1 molecule of crystalline water sodium glutamate which is equivalent to 1.00 mL of sodium-hydroxide standard titration solution
[c(NaOH)=1.000mol/L]. The unit is gram (g);
m - Mass of the sample. The unit is gram (g);
100 - Conversion factor.
It shall be expressed by the arithmetic mean of the two independent determination

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