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GB 5009.89-2023 English PDF (GB5009.89-2023)

GB 5009.89-2023 English PDF (GB5009.89-2023)

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GB 5009.89-2023: National food safety standard - Determination of niacin and niacinamide in foods
GB 5009.89-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Determination of Niacin
and Niacinamide in Foods
ISSUED ON. SEPTEMBER 6, 2023
IMPLEMENTED ON. MARCH 6, 2024
Issued by. National Health Commission of the People’s Republic of China;
State Administration for Market Regulation.
Table of Contents
Foreword... 3
1 Scope... 4
Method I - High Performance Liquid Chromatography... 4
2 Principle... 4
3 Reagents and Materials... 4
4 Instruments and Equipment... 5
5 Analytical Procedures... 6
6 Expression of Analysis Results... 8
7 Precision... 9
8 Others... 9
Method II - Microbiological Method... 9
9 Principle... 9
10 Reagents and Materials... 9
11 Instruments and Equipment... 11
12 Analytical Procedures... 12
13 Expression of Analysis Results... 17
14 Precision... 18
15 Others... 18
Appendix A Liquid Chromatogram of Niacin and Niacinamide Standard Solution... 19
Appendix B Preparation of Culture Medium... 20
National Food Safety Standard - Determination of Niacin
and Niacinamide in Foods
1 Scope
This Standard specifies the methods for the determination of niacin and niacinamide in foods.
In this Standard, Method 1 is applicable to the determination of niacin and niacinamide in
prepared milk powder, special dietary foods (excluding partially hydrolyzed milk protein
formulas, deeply hydrolyzed milk protein formulas or amino acid formulas, and infant formulas
for special medical purposes for amino acid metabolism disorders) and special-purpose
beverages. Method 2 is applicable to the determination of niacin (or niacinamide) in foods.
Method I - High Performance Liquid Chromatography
2 Principle
After pre-treatment, such as. enzymatic hydrolysis and protein precipitation, the sample is
extracted through ultrasonic oscillation in a weakly acidic environment, separated by C18
chromatographic column and detected by a UV detector. In accordance with the retention time
of the chromatographic peak, conduct qualitative determination, and adopt the external standard
method for quantitative determination. Calculate the content of niacin and niacinamide in the
specimen.
3 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are all analytically pure, and
the water is Grade-1 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Hydrochloric acid (HCl). guaranteed reagent.
3.1.2 Sodium hydroxide (NaOH). guaranteed reagent.
3.1.3 Methanol (CH3OH). chromatographically pure.
3.1.4 Isopropyl alcohol (C3H8O). chromatographically pure.
3.1.5 Sodium heptane sulfonate (C7H15NaO3S). chromatographically pure.
3.1.6 Amylase. enzyme activity  1.5 U/mg.
3.2 Preparation of Reagents
3.2.1 Hydrochloric acid solution (5.0 mol/L). measure-take 415 mL of hydrochloric acid and
add water to reach a constant volume of 1,000 mL.
3.2.2 Hydrochloric acid solution (0.1 mol/L). draw-take 8.3 mL of hydrochloric acid and add
water to reach a constant volume of 1,000 mL.
3.2.3 Sodium hydroxide solution (5.0 mol/L). weigh-take 200 g of sodium hydroxide and add
water to reach a constant volume of 1,000 mL.
3.2.4 Sodium hydroxide solution (0.1 mol/L). draw-take 20 mL of sodium hydroxide solution
(5.0 mol/L) and add water to reach a constant volume of 1,000 mL.
3.3 Reference Materials
3.3.1 Niacin (C6H5NO2, CAS. 59-67-6). purity  98%, or a standard substance certified by the
state and awarded a reference material certificate.
3.3.2 Niacinamide (C6H6N2O, CAS. 98-92-0). purity  98%, or a standard substance certified
by the state and awarded a reference material certificate.
3.4 Preparation of Standard Solutions
3.4.1 Niacin and niacinamide standard stock solution (1.000 mg/mL). place niacin (or
niacinamide) reference material into a desiccator containing phosphorus pentoxide and dry it
overnight. Respectively and accurately weigh-take 0.1 g (accurate to 1 mg), use 0.1 mol/L
hydrochloric acid to dissolve it, and reach a constant volume of 100 mL. It can be stored for 1
month when refrigerated at 2 C ~ 8 C.
3.4.2 Niacin and niacinamide standard mixed intermediate solution (100.0 g/mL). respectively
and accurately draw-take 10.0 mL of niacin and niacinamide standard stock solution into a 100
mL volumetric flask, add water to reach a constant volume to the scale, and evenly mix it. It
can be stored for 1 month when refrigerated at 2 C ~ 8 C.
3.4.3 Niacin and niacinamide standard mixed working solutions. respectively and accurately
draw-take 1.0 mL, 2.0 mL, 5.0 mL, 10.0 mL and 20.0 mL of the standard mixed intermediate
solution into 100 mL volumetric flasks, add water to reach a constant volume to the scale and
evenly mix them. Thus, standard mixed working solutions with a mass concentration of 1.0
g/mL, 2.0 g/mL, 5.0 g/mL, 10.0 g/mL and 20.0 g/mL are obtained. Prepare them right
before use.
4 Instruments and Equipment
4.1 High performance liquid chromatograph. equipped with UV detector or diode array detector.
4.2 Balance. with a division value of 0.1 mg and 0.01 g, respectively.
4.3 Constant-temperature incubator. 30 C ~ 80 C.
4.4 Ultrasonic equipment.
4.5 pH meter. with an accuracy of 0.1.
4.6 Pulverizer.
5 Analytical Procedures
5.1 Sample Pre-treatment
5.1.1 Specimen preparation
Sample pre-treatment. take at least 200 g of representative sample. For lumpy or granular
samples, use a pulverizer to pulverize them; for powdery, pasty or liquid samples, thoroughly
mix them and place them in a closed container.
5.1.2 Starches and starch-containing foods
5.1.2.1 Weigh-take about 5.0 g (accurate to 0.01 g) of evenly mixed solid specimen, place it in
a 150 mL conical flask, add about 25 mL of 45 C ~ 50 C water, add about 0.5 g of amylase,
shake it well, then, fill the conical flask with nitrogen, use a stopper to cap it, and place it in an
incubator at 50 C ~ 60 C for enzymatic hydrolysis for about 30 minutes. Take it out and cool
to room temperature.
5.1.2.2 Weigh-take about 20.0 g (accurate to 0.01 g) of evenly mixed liquid specimen, place it
in a 150 mL conical flask, add about 0.5 g of amylase, shake it well, then, fill the conical flask
with nitrogen, use a stopper to cap it, and place it in an incubator at 50 C ~ 60 C for enzymatic
hydrolysis for about 30 minutes. Take it out and cool to room temperature.
5.1.3 Starch-free foods
5.1.3.1 Weigh-take about 5.0 g (accurate to 0.01 g) of evenly mixed solid specimen, place it in
a 150 mL conical flask, and add about 25 mL of 45 C ~ 50 C water. Place it in ultrasonic
equipment and oscillate for more than 10 minutes to thoroughly dissolve it, let it stand for 5
minutes ~ 10 minutes, then, cool it to room temperature.
5.1.3.2 Weigh-take about 20.0 g (accurate to 0.01 g) of evenly mixed liquid specimen and place
it in a 150 mL conical flask. Place it in ultrasonic equipment and oscillate for more than 10
minutes to thoroughly dissolve it, let it stand for 5 minutes ~ 10 minutes, then, cool it to room
temperature.
5.1.4 Specimen extraction
After the specimen solution drops to room temperature, use 5.0 mol/L hydrochloric acid
solution and 0.1 mol/L hydrochloric acid solution to adjust the pH of the specimen solution to
factor 1.008.
7 Precision
The absolute difference between the results of two independent determinations obtained under
repeatability conditions shall not exceed 10% of the arithmetic mean.
8 Others
For solid samples. when the s...
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