GB 5009.93-2017 PDF English
US$70.00 · In stock · Download in 9 secondsGB 5009.93-2017: National food safety standard - Determination of selenium in foods Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedureStatus: Valid GB 5009.93: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB 5009.93-2017 | English | 70 |
Add to Cart
|
0-9 seconds. Auto-delivery
|
National food safety standard - Determination of selenium in foods
| Valid |
| GB 5009.93-2010 | English | 319 |
Add to Cart
|
3 days
|
National food safety standard -- Determination of selenium in foods
| Obsolete |
| GB/T 5009.93-2003 | English | 279 |
Add to Cart
|
3 days
|
Determination of selenium in foods
| Obsolete |
Excerpted PDFs (Download full copy in 9 seconds upon purchase)PDF Preview: GB 5009.93-2017
GB 5009.93-2017: National food safety standard - Determination of selenium in foods---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GB5009.93-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard -
Determination of selenium in foods
Issued on. APRIL 06, 2017
Implemented on. OCTOBER 06, 2017
Issued by. National Health and Family Planning Commission of the
People’s Republic of China;
China Food and Drug Administration.
Table of Contents
Foreword... 3
1 Scope... 4
2 Principle... 4
3 Reagents and materials... 4
4 Instruments and equipment... 6
5 Analysis procedure... 6
6 Expression of analysis results... 8
7 Precision... 8
8 Others... 8
9 Principle... 9
10 Reagents and materials... 9
11 Instruments and equipment... 11
12 Analysis procedure... 11
13 Expression of analysis results... 12
14 Precision... 13
15 Others... 13
Annex A Microwave digestion temperature rise program reference conditions
... 14
Foreword
This Standard replaces GB 5009.93-2010 “National food safety standard -
Determination of selenium in foods”, GB/T 21729-2008 “Tea - Determination of
selenium content”, SN/T 0860-2000 “Method for the determination of selenium in
canned mushroom for export - Fluorometry” and SN/T 0926-2000 “Method for the
determination of selenium in tea for import and export - Fluorimetry”.
Compare this Standard with GB 5009.93-2010, the main changes are as follows.
- RETAIN the hydride atomic fluorescence spectrometry as Method I, fluorescence
spectrophotometry as Method II;
- ADD the inductively coupled plasma mass spectrometry as Method III.
National food safety standard -
Determination of selenium in foods
1 Scope
This Standard specifies the determination of selenium content in foods by hydride
atomic fluorescence spectrometry, fluorescence spectrometry and inductively coupled
plasma mass spectrometry.
This Standard applies to the determination of selenium in all types of foods.
Method I -- Hydride atomic fluorescence spectrometry
2 Principle
After the sample is acid-heated and digested, in the 6 mol/L hydrochloric acid medium,
the hexavalent selenium in the sample is reduced to tetravalent selenium. Sodium
borohydride or potassium borohydride is used as the reducing agent to reduce the
tetravalent selenium in the hydrochloric acid medium to hydrogen selenide, which is
introduced by carrier gas (argon) into the atomizer for atomization.
3 Reagents and materials
Unless otherwise indicated, the reagents used in this method are analytical regents,
and the water is the Grade 2 water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3). excellent regent.
3.1.2 Perchloric acid (HClO4). excellent regent.
3.1.6 Sodium borohydride (NaBH4). excellent regent.
3.1.7 Potassium ferricyanide [K3Fe(CN)6].
3.2 Preparation of reagents
3.2.1 Nitric acid - perchloric acid mixed acid (9 + 1). MIX 900 mL of nitric acid with 100
mL of perchloric acid.
3.2.2 Sodium hydroxide solution (5 g/L). WEIGH 5 g of sodium hydroxide; DISSOLVE
in 1000 mL of water; MIX well.
3.3 Standard
Selenium standard solution. 1000 mg/L, or selenium standard solution at a certain
concentration certified by the state and awarded the standard substance certificate.
3.4 Preparation of standard solutions
3.4.1 Selenium standard intermediate solution (100 mg/L). accurately PIPETTE 1.00
mL of selenium standard solution (1000 mg/L) in a 10 mL volumetric flask; ADD
hydrochloric acid solution (5 + 95) to the mark; MIX well.
4 Instruments and equipment
NOTE. All glassware and polytetrafluoroethylene digestion inner tank must be soaked in nitric
acid solution (1 + 5) overnight, washed repeatedly with tap water, and finally rinsed with water.
4.1 Atomic fluorescence spectrometer. with selenium hollow cathode lamp.
4.4 Microwave digestion system. with polytetrafluoroethylene digestion inner tank.
5 Analysis procedure
5.1 Sample preparation
NOTE. Sample contamination shall be avoided during sampling and preparation processes.
5.1.1 Cereal, bean samples
The sample, after the debris are removed and being crushed, is stored in plastic bottles.
5.2 Sample digestion
5.2.1 Wet digestion
WEIGH 0.5 g ~ 3 g (to the nearest 0.001 g) of solid sample or accurately PIPETTE
1.00 mL ~ 5.00 mL of liquid sample; PLACE in a conical flask; ADD 10 mL of nitric acid
- perchloric acid mixed acid (9 + 1) and a few glass beads; COVER the surface dish
for cold digestion overnight. The next day, HEAT on the electric hot plate, and timely
ADD nitric acid. When the solution becomes clear and colorless and accompanied by
white smoke, continue to HEAT until the remaining volume is about 2 mL.
5.2.2 Microwave digestion
WEIGH 0.2 g ~ 0.8 g (to the nearest 0.001 g) of solid sample or accurately PIPETTE
1.00 mL ~ 3.00 mL of liquid sample; PLACE in the digestive tube; ADD 10 mL of nitric
acid and 2 mL of hydrogen peroxide; SHAKE to mix well. DIGEST in the microwave
digestion instrument, and the recommended microwave digestion conditions are
shown in Annex A (set digestion conditions according to different instruments).
5.3 Determination
5.3.1 Instrument reference conditions
Adjust the instruments to the best condition according to their performance. Reference
conditions. negative high voltage 340 V; lamp current 100 mA; atomization
temperature 800 °C; furnace height 8 mm; carrier gas flow rate 500 mL/min; shielding
gas flow rate 1000 mL/min; standard curve method of measurement method; peak
area of reading method; delay time 1 s; reading time 15 s; solution adding time 8 s;
sample injection volume 2 mL.
6 Expression of analysis results
The content of selenium in the sample is calculated according to equation (1).
7 Precision
The absolute difference between two independent determination results obtained
under repeatability conditions shall not exceed 20 % of the arithmetic mean.
8 Others
When the sample volume is 1 g (or 1 mL) and the constant volume is 10 mL, the limit
of detection is 0.002 mg/kg (or 0.002 mg/L) and the limit of quantification is 0.006
mg/kg (or 0.006 mg/L) for this method.
9 Principle
The sample is digested with mixed acid to convert the selenium compound to inorganic
selenium Se4+.
10 Reagents and materials
Unless otherwise specified, the reagents used in this method are analytical regents,
and the water is Grade 2 water as specified in GB/T 6682.
10.1 Reagents
10.1.1 Hydrochloric acid (HCl). excellent regent.
10.1.6 Cresol red (C21H18O5S).
10.1.7 Ammonia (NH3 • H2O). excellent regent.
10.2 Preparation of reagents
10.2.1 Hydrochloric acid solution (1 %). MEASURE 5 mL of hydrochloric acid; DILUTE
to 500 mL with water; MIX well.
10.2.4 Hydrochloric acid solution (6 mol/L). MEASURE 50 mL of hydrochloric acid;
slowly ADD to 40 mL of water; COOL; ADD water to 100 mL; MIX well.
10.2.5 Ammonia solution (1 + 1). MIX 5 mL of water with 5 mL of ammonia.
10.2.6 EDTA mixture.
10.3 Standard
Selenium standard solution. 1000 mg/L, or selenium standard solution at a certain
concentration certified by the state and awarded the standard substance certificate.
10.4 Preparation of standard solutions
10.4.1 Selenium standard intermediate solution (100 mg/L). accurately PIPETTE 1.00
mL of selenium standard solution (1000 mg/L) in a 10 mL volumetric flask; DILUTE
with hydrochloric acid solution (1 %) to the mark; MIX well.
10.4.2 Selenium standard use solution (50.0 μg/L). accurately PIPETTE 0.50 mL of
selenium standard intermediate solution (100 mg/L); DILUTE with hydrochloric acid
solution (1 %) to 1000 mL; MIX well.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
Tips & Frequently Asked QuestionsQuestion 1: How long will the true-PDF of English version of GB 5009.93-2017 be delivered?Answer: The full copy PDF of English version of GB 5009.93-2017 can be downloaded in 9 seconds, and it will also be emailed to you in 9 seconds (double mechanisms to ensure the delivery reliably), with PDF-invoice. Question 2: Can I share the purchased PDF of GB 5009.93-2017_English with my colleagues?Answer: Yes. The purchased PDF of GB 5009.93-2017_English will be deemed to be sold to your employer/organization who actually paid for it, including your colleagues and your employer's intranet. Question 3: Does the price include tax/VAT?Answer: Yes. Our tax invoice, downloaded/delivered in 9 seconds, includes all tax/VAT and complies with 100+ countries' tax regulations (tax exempted in 100+ countries) -- See Avoidance of Double Taxation Agreements (DTAs): List of DTAs signed between Singapore and 100+ countriesQuestion 4: Do you accept my currency other than USD?Answer: Yes. www.ChineseStandard.us -- GB 5009.93-2017 -- Click this link and select your country/currency to pay, the exact amount in your currency will be printed on the invoice. Full PDF will also be downloaded/emailed in 9 seconds. Question 5: Should I purchase the latest version GB 5009.93-2017?Answer: Yes. Unless special scenarios such as technical constraints or academic study, you should always prioritize to purchase the latest version GB 5009.93-2017 even if the enforcement date is in future. Complying with the latest version means that, by default, it also complies with all the earlier versions, technically. How to buy and download a true PDF of English version of GB 5009.93-2017?A step-by-step guide to download PDF of GB 5009.93-2017_EnglishStep 1: Visit website https://www.ChineseStandard.net (Pay in USD), or https://www.ChineseStandard.us (Pay in any currencies such as Euro, KRW, JPY, AUD).
Step 2: Search keyword "GB 5009.93-2017".
Step 3: Click "Add to Cart". If multiple PDFs are required, repeat steps 2 and 3 to add up to 12 PDFs to cart.
Step 4: Select payment option (Via payment agents Stripe or PayPal).
Step 5: Customize Tax Invoice -- Fill up your email etc.
Step 6: Click "Checkout".
Step 7: Make payment by credit card, PayPal, Google Pay etc. After the payment is completed and in 9 seconds, you will receive 2 emails attached with the purchased PDFs and PDF-invoice, respectively.
Step 8: Optional -- Go to download PDF.
Step 9: Optional -- Click Open/Download PDF to download PDFs and invoice.
See screenshots for above steps: Steps 1~3 Steps 4~6 Step 7 Step 8 Step 9
|