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GB/T 21728-2008: Determination of fluoride content n brick tea
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| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | Status | PDF |
| GB/T 21728-2008 | English | 139 |
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Determination of fluoride content n brick tea
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GB/T 21728-2008
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Basic data | Standard ID | GB/T 21728-2008 (GB/T21728-2008) | | Description (Translated English) | Determination of fluoride content n brick tea | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | X04 | | Classification of International Standard | 67.140.10 | | Word Count Estimation | 6,655 | | Date of Issue | 2008-05-04 | | Date of Implementation | 2008-10-01 | | Quoted Standard | GB/T 8302; GB/T 8303 | | Regulation (derived from) | National Standard Approval Announcement 2008 No.6 (Total No.119) | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This standard specifies the use of ion-selective electrodes detect brick fluoride content approach. This standard applies to brick fluorine content of the finished product and raw material testing. | GB/T 21728-2008: Determination of fluoride content n brick tea---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Determination of fluoride content n brick tea
ICS 67.140.10
X04
National Standards of People's Republic of China
Detection brick tea fluoride content
Posted 2008-05-04
2008-10-01 implementation
Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China
Standardization Administration of China released
Foreword
This standard is proposed and managed by China Federation of Supply and Marketing Cooperatives.
This standard was drafted. China Federation of Supply and Marketing Cooperatives Hangzhou Tea Research Institute.
The main drafters of this standard. Zhou Weilong, Xu Jianfeng, Weng Kun.
Detection brick tea fluoride content
1 Scope
This standard specifies the ion selective electrode detection method of brick tea fluoride content.
This standard applies to raw materials and finished brick fluorine content test.
2 Normative references
The following documents contain provisions which, through reference in this standard and become the standard terms. For dated references, subsequent
Amendments (not including errata content) or revisions do not apply to this standard, however, encourage the parties to the agreement are based on research
Whether the latest versions of these documents. For undated reference documents, the latest versions apply to this standard.
GB/T 8302 sampling tea
Sample Preparation and Determination of dry matter content GB/T 8303 Tea grated
3 Terms and Definitions
The following terms and definitions apply to this standard.
3.1
Including black tea, Fu brick tea, flower tea, brick tea, Kang brick tea, rice tea, golden tip tea, tea tight, Tuocha like.
Principle 4
FISE lanthanum fluoride single-crystal film of the fluoride ion selective response to produce the number of fluorine electrode and a saturated calomel electrode in the test
Test solution, the potential difference can change with the solution of fluorine ion activity changes, variation in line with the Nernst potential (Nernst) equation,
See equation (1).
E = E0-2.303RTF lg Ba F
- (1)
Where.
E --- electromotive force, in millivolts (mV);
E0 --- under certain experimental conditions constant value, in millivolts (mV);
R --- molar gas constant, 8.31441J/(mol · K);
T --- thermodynamic temperature, the unit is open (K);
F --- Faraday constant, 96486.70C/mol;
---- F. Ba fluoride ion concentration in units of moles per liter (mol/L).
E and lg Ba F- linear. 2.303RT/F for the slope of the line (25 ℃ when 59.16). Fluoride ion forms a complex with the
Fe3 +, Al3 + and SiO32- plasma interfere with the determination of other common ions had no effect, the acidity of the liquid is measured pH5 ~ 6, the total ionic strength adjustment
Festival buffer eliminate interfering ions and its acidity.
5 Instruments
5.1 fluorine electrode. PF-1 type or other models.
5.2 pH meter. pHS-2 type or potentiometer.
5.3 magnetic stirrer.
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