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GB 5009.93-2010 English PDF

GB 5009.93-2010_English: PDF (GB5009.93-2010)
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GB 5009.93-2010English319 Add to Cart 3 days [Need to translate] National food safety standard -- Determination of selenium in foods Obsolete GB 5009.93-2010
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BASIC DATA
Standard ID GB 5009.93-2010 (GB5009.93-2010)
Description (Translated English) National food safety standard. Determination of selenium in foods
Sector / Industry National Standard
Classification of Chinese Standard C53
Classification of International Standard 67.040
Word Count Estimation 8,848
Date of Issue 2010-03-26
Date of Implementation 2010-06-01
Older Standard (superseded by this standard) GB/T 5009.93-2003
Regulation (derived from) Circular of the Ministry of Health (2010)7
Issuing agency(ies) Ministry of Health of People's Republic of China
Summary This Chinese standard specifies the use hydride generation atomic fluorescence spectrometry and fluorescence method for the determination of selenium in foods approach. This standard applies to the determination of selenium in foods.

Standards related to: GB 5009.93-2010

GB 5009.93-2010
National food safety standard.Determination of selenium in foods
National Standards of People's Republic of China
National Food Safety Standard
Determination of Selenium in Food
National food safety standard
Determination of selenium in foods
People's Republic of China Ministry of Health issued
Issued on. 2010-03-26
2010-06-01 implementation
Foreword
This standard replaces GB/T 5009.93-2003 "Determination of selenium in foods."
This standard replaces the standards previously issued as follows.
--GB/T 5009.93-2003;
--GB/T 12399-1996;
--GB 13105-1991.
National Food Safety Standard
Determination of Selenium in Food
1 Scope
This standard specifies the method for the determination of selenium in foods by hydride generation atomic fluorescence spectroscopy and fluorescence.
This standard applies to the determination of selenium in food.
2 Normative references
The standard file referenced in the application of this standard is essential. For dated references, only the edition date of the note
Apply to this standard. For undated references, the latest edition (including any amendments) applies to this standard.
The first method hydride generation atomic fluorescence spectrometry
Principle 3
After heating the sample by acid digestion, at 6 mo1/L HCl medium, the reduction of hexavalent selenium in the sample into tetravalent selenium, sodium boron hydride or boron
Potassium hydride as the reducing agent, the reduction of tetravalent selenium in the medium of hydrochloric acid into hydrogen selenide (H2Se), by a carrier gas (argon) into the atomizer into
Line atomization in selenium hollow cathode lamp illumination, the ground state of selenium atoms are excited to high energy state, the deactivation to the ground state, emitting a characteristic wave
Long fluorescence, and fluorescence intensity is proportional to the selenium content. Quantitative comparison with the standard series.
4 Reagents and materials
Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provisions tertiary water.
4.1 Nitric acid. pure class distinctions.
4.2 perchloric acid. pure class distinctions.
4.3 hydrochloride. pure class distinctions.
4.4 mixed acid. nitric acid and perchloric acid of 9. 1 volume mix.
4.5 Sodium hydroxide. pure class distinctions.
4.6 a solution of sodium borohydride (8 g/L). Weigh 8.0 g of sodium borohydride (of NaBH4), was dissolved in sodium hydroxide solution (5 g/L), and then
The volume to 1000 mL, and mix.
4.7 ferricyanide (100 g/L). Weigh 10.0 g potassium ferricyanide [(K3Fe (CN) 6)], was dissolved in 100 mL of water, and mix.
4.8 selenium standard stock solution. Weigh 100.0 mg selenium (spectroscopically pure), was dissolved in a small amount of nitric acid, add 2 mL perchloric acid, boiling water bath
Heated 3 h ~ 4 h, after cooling plus 8.4 mL of hydrochloric acid, then cook in boiling water bath for 2 min, accurately diluted to 1000 mL, the concentration of hydrochloric acid
Of 0.1 mo1/L, the concentration of the stock solution is equivalent to 100 μg of selenium per milliliter.
4.9 selenium standard application solution. take 100μg/mL stock selenium standard solution 1.0 mL, the volume to 100 mL, this application concentration of 1μg/mL.
Note. You can also purchase the certified national standard element solution.
4.10 hydrochloric acid (6 mol/L). Measure 50 mL of hydrochloric acid (4.3) slowly added 40 mL of water, cool and dilute to 100 mL.
4.11 Hydrogen peroxide (30%).
5. Apparatus
5.1 atomic fluorescence spectrometer with selenium hollow cathode lamp.
5.2 Electric hot plate.
5.3 microwave digestion system.
5.4 Balance. a sense of the amount of 1 mg.
5.5 mill.
5.6 oven.
Step 6 Analysis
6.1 Sample Preparation
6.1.1 Food. The specimen was washed with water three times, at 60 ℃ drying, grinding, store in a plastic bottle and set aside.
6.1.2 vegetables and other plant foods. Take the edible portion washed with water with gauze to absorb water droplets, homogenised reserve.
6.1.3 Other solid samples. crushing, mixing spare.
6.1.4 Liquid Sample. Mix and set aside.
6.1.5 Sample Digestion
6.1.5.1 Electric heating digestion board. Weigh 0.5 g ~ 2 g (accurate to 0.001g) sample, the liquid sample drawn 1.00mL ~ 10.00 mL,
Placed digestion flask, add 10.0 mL of mixed acid and a few grains of glass beads, cover the surface of the dish cold digestion overnight. The next day on a hot plate heated and and
When supplemented with nitric acid. When the solution becomes clear and colorless with white smoke, and heating was continued to a residual volume of about 2 mL, must not be evaporated to dryness. cold
But, along with 5.0 mL of hydrochloric acid (4.10), and heating was continued until the solution becomes clear and colorless with white smoke appears, restore the hexavalent selenium to tetravalent
selenium. Cooled, transferred to a 50 mL volumetric flask to volume and mix aside. While doing the blank test.
6.1.5.2 Microwave Digestion. Weigh 0.5 g ~ 2 g (accurate to 0.001g) in the digestive tract sample, add 10 mL of nitric acid, 2 mL peroxide
Hydrogen, shaking mixing, digestion in microwave digestion instrument, which digest the recommended conditions are shown in Table 1 (self-digestion can be set according to different instruments
condition).
Table 1 Recommended conditions of microwave digestion
After cooling into the flask, add a few grains of glass beads, hot plate heating was continued until nearly dry, must not evaporated. Plus 5.0 mL salt
Acid (4.10), and heating was continued until the solution becomes clear and colorless with white smoke appears, hexavalent selenium reduced to tetravalent selenium. Cool, and transferred the sample
STAGE POWER RAMP ℃ HOLD
1 1600 W 100% 6.00 120 ℃ 1.00
2 1600 W 100% 3.00 150 ℃ 5.00
3 1600 W 100% 5.00 200 ℃ 10.00
Digestion in 25 mL volumetric flask to volume and mix aside. While doing the blank test.
Absorb 10.0 mL sample digestion in 15 mL centrifuge tube, add hydrochloric acid (4.3) 2.0 mL, iron potassium cyanide solution (4.7) 1.0 mL,
Mix tested.
6.2 preparation of standard curve
Were taken 0.00 mL, 0.10 mL, 0.20 mL, 0.30 mL, 0.40 mL, 0.50 mL standard application solution in 15 mL centrifuge tube with
Deionized water volume to 10 mL, respectively, and then add hydrochloric acid (4.3) 2 mL, iron potassium cyanide solution (4.7) 1.0 mL, mix, made of standard workers
For the curve.
6.3 Determination
6.3.1 Instrument Reference conditions. negative high voltage. 340 V; lamp current. 100 mA; atomization temperature. 800 ℃; furnace height. 8 mm; carrier gas
Flow rate. 500 mL/min; shielding gas flow rate. 1000 mL/min; measurement method. standard curve method; reading mode. peak area; delay
Room. 1 s; reading time. 15 s; dosing time. 8 s; injection volume. 2 mL.
6.3.2 Determination of. setting the optimal conditions for the instrument, the furnace temperature was raised gradually to the desired temperature, start measuring stable after 10 min ~ 20 min.
Continuous series of zero standard tube injection until after the reading has stabilized, the standard series of measurements into the standard curve. Into the sample measurement points
Do not blank and sample measurement sample digestion, before each test different samples should be cleaned injector. The measurement results calculated according to the sample 7.
7 expression analysis
According to equation (1) calculate the content of selenium in the sample.
1000) (0
××
×× - =
VCCX. (1)
Where.
X - sample selenium content in milligrams per kilogram or milligrams per liter (mg/kg or mg/L);
C - determining the concentration of sample digestion, in units of nanograms per milliliter (ng/mL);
0C - blank samples to determine the concentration of digestive juice, unit nanograms per milliliter (ng/mL);
m - mass of the sample (by volume) in grams or milliliters (g or mL);
V - sample digestion total volume in milliliters (mL).
The arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures.
8 Precision
Two independent determination results under the absolute difference in repeatability condition must not exceed 10% of the arithmetic mean.
The second method Fluorescence
Principle 9
The sample was digested with a mixed acid, selenium compound oxidation of inorganic selenium Se4, under acidic conditions Se4 with 2,3-diaminonaphthalene
(2,3-Diaminonaphthalene, abbreviated as DAN) reacts 4,5 Benzopiaselenol selenium brain (4,5-Benzo piaselenol), then
Cyclohexane extraction. Fluorescence intensity was measured at an excitation wavelength of 376 nm, emission wavelength of 520 nm condition to calculate the sample
Selenium.
10 Reagents and materials
Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provisions tertiary water.
10.1 selenium standard solution. Weigh accurately element selenium (spectroscopically pure) 100.0 mg, dissolved in a small amount of concentrated nitric acid, perchloric acid was added 2 mL (70% to 72
%), Boiling water bath to 3 h ~ 4 h, added 8.4 mL HCl (hydrochloric acid concentration of 0.1 mol/L) after cooling. Then cook in boiling water bath
2min. Accurately diluted to 1000 mL, this is the stock solution (Se content. 100 μg/mL). With 0.1 mol/L hydrochloric acid stock solution using
Diluted to 0.05 μg per ml selenium. In the refrigerator, valid for two years.
10.2 DAN reagent (1.0g/L). This reagent formulated in a dark room. Weigh DAN (purity 95% ~ 98%) 200 mg in the vicinity of the cone cover
Shaped flask, 0.1 mol/L hydrochloric acid, 200 mL, was shaken for about 15 min it has completely dissolved. Add about 40 mL cyclohexane, continue to oscillate 5
min. This solution was poured stuffed with glass wool (or cotton) in a separatory funnel, to be layered cyclohexane layer was filtered, collected DAN solution layer,
Purification by repeated with cyclohexane until the cyclohexane until minimize fluorescence (about 5 to 6 times purification). The DAN storage solution purified in brown
Color bottle, add about 1 cm thick cover surface cyclohexane, into the refrigerator. If necessary, prior to use purified once again with cyclohexane.
Warning. This reagent has some toxicity, the use of this reagent should be regular staff laboratory work experience. The user's responsibility to take appropriate safety and health measures,
And to ensure compliance with the relevant provisions of the State regulations.
10.3 mixed acid. nitric acid and perchloric acid are mixed in 91 volumes.
Sulfuric acid to 10.4 Selenium. Take 200 mL of concentrated sulfuric acid was slowly poured into 200 mL of water, was added 48% hydrobromic acid 30 mL, mix, sand bath to
On heating to appear white smoke, then the volume should be 200 mL.
10.5 EDTA mixture
10.5.1 EDTA solution (0.2 mol/L). Weigh disodium EDTA 37 g, add water and heated until completely dissolved, cooled and diluted to
500 mL;
10.5.2 hydroxylamine hydrochloride solution (100 g/L). Weigh 10 g of hydroxylamine hydrochloride dissolved in water and dilute to 100 mL;
10.5.3 cresol red indicator (0.2 g/L). Weigh 50 mg of cresol red dissolved in a little water, add ammonia (11) 1 drop until completely dissolved
After the solution diluted with water to 250 mL.
10.5.4 take EDTA solution (10.5.1) and hydroxylamine hydrochloride solution (10.5.2) for each 50 mL, plus cresol red indicator (10.5.3) 5 mL,
Diluted with water to 1 L, and mix.
Ammonia 10.6 (11).
10.7 hydrochloric acid.
10.8 Cyclohexane. the need to test whether the fluorescent impurities, distilled otherwise after use, used recycled cyclohexane, redistilled before use.
10.9 hydrochloric acid (19).
11 instruments and equipment
11.1 fluorescence spectrophotometer.
11.2 balance. a sense of the amount of 1mg.
11.3 oven.
11.4 mill.
11.5 heating plate.
11.6 water bath.
12 analysis steps
12.1 sample processing
12.1.1 Food
The sample was washed with water three times, to 60 ℃ oven drying to the surface water, ground with a grinder, store in a plastic bottle, put a packet of camphor fine,
Cork tightly and stored for use.
12.1.2 vegetables and other plant foods
Take the edible portion, after rinsed with distilled water three times, with gauze to absorb water droplets, stainless steel knife chopped, take a certain amount of the sample in an oven at 60 ℃
Dried, weighed and calculated moisture. Smash and set aside.
The calculation should be converted into the fresh weight.
12.1.3 other solid samples
Crushing, mixing the sample and set aside.
12.1.4 liquid sample
Mixing the sample and set aside.
12.2 digested sample
Se said about 0.01 μg ~ 0.5 μg of grain or vegetable and animal specimens 0.5 g ~ 2 g (accurate to 0.001g), a liquid sample
After the draw 1.00mL ~ 10.00 mL in grinding mouth Erlenmeyer flask, add 10 mL 5% sulfuric acid to the selenium, the sample to be moist, plus 20 mL of mixed acid
It was allowed to stand overnight and the next day was gradually heated on a hot plate set. When the violent reaction, the solution was colorless, continue heating until white fumes are generated at this time
Solution gradually turned yellow, reached the end. Some vegetables turbid samples after digestion, making it difficult to determine the end point, then you can pay attention to the bottle
Billowing white smoke appears, at the moment immediately removed, and the solution was cooled and then became colorless. Some higher selenium vegetables contain more Se6, need
After digestion plus 10 mL 10% hydrochloric acid, and heating was continued, so that the end point come back to fully restore Se6 as Se4, otherwise the result will be low.
12.3 Determination
Said digested sample solution was added 20.0 mL EDTA mixture with aqueous ammonia (10.6) and hydrochloric acid (10.9) adjusted to reddish orange
(PH 1.5 ~ 2.0). The following steps in the darkroom operations. add DAN reagent (10.2) 3.0 mL, after mixing, boiling water bath for 5 min,
After removing the cooling, cyclohexane, 3.0 mL, shaken for 4 min, the entire solution into a separating funnel, to be layered aqueous layer was discarded, carefully ring
Hexane layer is made of a separating funnel catchy poured into a lidded test tube, rendering cyclohexane mixed with water droplets, on a fluorescence spectrophotometer with excitation wavelength
376 nm, emission wavelength 520 nm fluorescence intensity 4,5 Benzopiaselenol selenium brain.
12.4 selenium standard curve drawing
Accurately taken selenium standard solution (0.05 μg/mL) 0.00 mL, 0.20 mL, 1.00 mL, 2.00 mL and 4.00 mL, 0.00 equivalent
μg, 0.01 μg, 0.05 μg, 0.10 μg and 0.20 μg selenium, add water to 5.0 mL, press sample measurement step is measured simultaneously.
When the selenium content in the 0.5 μg or less fluorescence intensity and a linear relationship between selenium content in the conventional measurement sample each time just to do a reagent blank
White and selenium content similar to standard sample tube (in duplicate) can be.
12.5 Analysis of the results presentation
Selenium content in the sample according to equation (2).
FF
FF
mX 02
1 - × - = (2)
Where.
X-- sample selenium content in micrograms per gram or microgram per milliliter (μg/g or μg/mL);
m1-- tube selenium mass, in micrograms (μg);
F1-- selenium standard fluorescence readings;
F2-- sample fluorescence readings;
F0-- blank tube fluorescence readings;
Quality m-- sample in grams or milliliters (g or mL).
The arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures.
13 Precision
Two independent determination results under the absolute difference in repeatability condition must not exceed 10% of the arithmetic mean.
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