GB 6851-2008_English: PDF (GB6851-2008)
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pH primary reagent -- General rules for certification
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GB 6851-2008
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pH Basic line--General rules for certification
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| Standard ID | GB 6851-2008 (GB6851-2008) | | Description (Translated English) | pH primary reagent. General rules for certification | | Sector / Industry | National Standard | | Classification of Chinese Standard | G60 | | Classification of International Standard | 71.040.30 | | Word Count Estimation | 12,195 | | Date of Issue | 2008-06-18 | | Date of Implementation | 2009-06-01 | | Older Standard (superseded by this standard) | GB 6851-1986 | | Quoted Standard | GB/T 601; GB/T 603; GB/T 6682 | | Drafting Organization | China Institute of Metrology | | Administrative Organization | National Standardization Technical Committee of chemical reagents chemical branch | | Regulation (derived from) | Announcement of Newly Approved National Standards No. 10 of 2008 (total 123) | | Proposing organization | China Petroleum and Chemical Industry Association | | Issuing agency(ies) | Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China | | Summary | This Chinese standard is suitable for use with liquid junction dihydrotestosterone battery electrode pH measurement pH value of the reference reagent (25��C). | | Standard ID | GB 6851-1986 (GB6851-1986) | | Description (Translated English) | pH Basic line--General rules for certification | | Sector / Industry | National Standard | | Classification of Chinese Standard | G61 | | Classification of International Standard | 71.040.30 | | Word Count Estimation | 11,116 | | Date of Issue | 1986/9/6 | | Date of Implementation | 1987/8/1 | | Regulation (derived from) | Announcement of Newly Approved National Standards No. 10, 2008 (No. 123 overall) | | Proposing organization | Ministry of Chemical Industry of the People Republic of China | | Issuing agency(ies) | National Bureau of Standards | | Summary | This Standard is applicable to have a liquid junction cell dihydrotestosterone pH electrode to measure the pH value of the reference reagents. The standard precision of �� 0. 002pH, uncertainty of �� 0. 01pH. |
GB 6851-2008
pH primary reagent.General rules for certification
ICS 71.040.30
G60
National Standards of People's Republic of China
Replacing GB 6851-1986
Posted 2008-06-18
2009-06-01 implementation
Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China
Standardization Administration of China released
Foreword
The standard 5.2, Chapter 6, Chapter 7, Chapter 8 is mandatory, the rest are recommended.
This standard replaces GB 6851-1986 "pH value reference reagent Law", compared with GB 6851-1986 The main changes are as follows.
--- Modify the "Range" (1986 edition Chapter 1, Chapter 1 of this edition);
--- "Terminology" added "a reference standard material", the "a reference reagent pH" is replaced by "pH standard reference material", the "a
Level pH standard buffer solution "to" pH reference buffer solution "(1986 edition Chapter 2, Chapter 3 of this edition);
--- Modify the "Instrument" chapter (1986 edition, Chapter 4, Chapter 6 of this edition);
--- Modify the "Reagents and Materials" chapter (1986 edition Chapter 5, Chapter 5 of this edition);
--- Modify the "Calculate" chapter (1986 edition, Chapter 7, Chapter 8 of this edition);
--- Increased (Chapter 9 of this edition) "pH standard buffer solution of pH value (pH (S) Ⅱ) expanded uncertainty";
--- Revised Appendix A, Appendix B (1986 edition Appendix A, Appendix B, Appendix C, this edition of Appendix A, Appendix B);
--- Added "expanded uncertainty calculated pH standard buffer solution pH value" (Excerpts Appendix C).
This standard Annex A, Annex B is normative appendix, Appendix C is informative appendix.
The standard proposed by China Petroleum and Chemical Industry Association.
This standard by the Chemicals Branch of the National Chemical Standardization Technical Committee.
This standard is drafted by. China Institute of Metrology, Beijing Institute of Chemical reagents.
The main drafters of this standard. repair Hongyu, Han Baoying.
This standard replaces the standards previously issued as follows.
--- GB 6851-1986.
1 Scope
This method is applicable to the liquid junction cell measuring pH electrode dihydrotestosterone reference reagent pH value (25 ℃).
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 Preparation (GB/T 601-2002, ISO 6353-1. 1982, NEQ)/T 601 chemical reagent standard titration solution
GB/T 603 chemical reagent test method Preparations of articles (GB/T 603-2002, ISO 6353-1 with. 1982,
NEQ)
GB/T 6682 analytical laboratory use specifications and test methods (GB/T 6682-2008, ISO 3696. 1987, MOD)
3 Terms and Definitions
The following terms and definitions apply to this standard.
3.1
Having the highest metrological characteristics of the reference method for determining standard substance characteristic values, referred to reference material. Reference material is normally provided by States
House calibration laboratory research, values traceable to SI units, and the organization of international verification by international comparison measurement, achieved an equivalent degree.
3.2
Reference silver/silver chloride electrode, liquid junction cells without reference method, the aqueous solution pH (acidity) reference means of the set value - platinum (palladium) hydrogen
Standard material. It is commonly used reference reagent and pH value two pH standard materials and high-precision pH meter verification/calibration.
3.3
To measure pH standard reference material based on hydrochlorothiazide liquid junction electrodes and battery comparison value chemicals. It uses
At pH meter calibration.
3.4
Buffer solution with pH standard reference material prepared according to the method prescribed.
3.5
Reference reagent with a pH buffer solution prepared as prescribed.
3.6
With a pH value of 3.2 baseline methodology buffer pH value of the solution.
3.7
With a pH value of 3.3 standard methods of buffer pH value of the solution.
4 principle of the method
The general rule in four standard pH value of the buffer solution with the existing four pH reference buffer solution of the same name, with concentrations
Etc., so can be used in response to the hydrogen electrode in a solution of hydrogen ions, the pH reference buffer solutions and pH buffer solution into the same measurement standard
Battery (liquid junction electrodes dihydrotestosterone cell) measurements were compared to determine the magnitude of the pH standard buffer solution.
The measuring cell is as follows.
Pt (Pd), hydrogen (gas) pH reference
Buffer solution
Saturated potassium chloride pH standard
Buffer solution
Hydrogen (gas), platinum (Pd)
At a constant temperature, according to the Nernst (Nernst) equation.
Left half-cell potential is.
EⅠ = -ln10
· R · T
· PH (S) Ⅰ + EjⅠ (1)
Right half-cell potential is.
EⅡ = -ln10
· R · T
· PH (S) Ⅱ + EjⅡ (2)
Where. EjⅠ and EjⅡ to the left and right battery liquid junction potential, respectively.
Electromotive force E is.
E = EⅠ -EⅡ = -ln10
· R · T
[PH (S) Ⅰ -pH (S) Ⅱ] + (EjⅠ -EjⅡ) (3)
Order ΔEj = EjⅠ-EjⅡ
pH (S) Ⅰ -pH (S) Ⅱ = -
F · (E-ΔEj)
ln10 · R · T
(4)
Then, pH standard buffer solution of pH value (pH (S) Ⅱ) by the formula (5) is calculated.
pH (S) Ⅱ = pH (S) Ⅰ +
F · (E-ΔEj)
ln10 · R · T
(5)
Where.
pH (S) Ⅰ --- pH value of the reference buffer solution of pH;
--- Faraday constant F., Units of coulombs per mole (C/mol);
E --- electromotive force in volts (V);
ΔEj --- residual liquid junction potential, in volts (V);
--- Gas constant R & lt joules per (open Moore) (J/mol · K);
T --- thermodynamic temperature in Kelvin (K).
At 25 ℃. ln10
· R · T
F = 0.059157
(V)
Since the pH reference buffer solutions and pH standard buffer solution ionic strength can be considered the same species and, after selection by measuring the battery,
Reduced the residual liquid junction potential small (≤0.05mV) enough. In this case, ΔEj can be considered approximately equal to zero, then the pH standard buffer solution
pH value (pH (S) Ⅱ) formula can be simplified to formula (6).
pH (S) Ⅱ = pH (S) Ⅰ + F
· E
ln10 · R · T
(6)
5 Reagents and materials
5.1 General provisions
Unless otherwise specified in this standard, the standard solution, preparations and products, according to GB/T 601, the provisions of the preparation of GB/T 603, laboratory
Water should be consistent with GB/T 6682 in two water specifications. The use of high-purity hydrogen gas. The solution to both mass "%" represents
fraction.
Weigh 10.12g bake at 110 ℃ ± 5 ℃ to constant of the sample, dissolved in water and diluted to 1000mL at 20 ℃ ± 5 ℃ when.
Weigh 3.387g at 115 ℃ ± 5 ℃ drying to constant potassium dihydrogen phosphate and 3.533g at 115 ℃ ± 5 ℃ drying to a constant amount of hydrogen phosphate
Disodium was dissolved in water and diluted to 1000mL at 20 ℃ ± 5 ℃ when.
Weigh 3.80g (drier in excess of sodium chloride and sucrose crystals) in a saturated solution of sodium chloride and sucrose dryer and dried to constant
Amount of sample, no carbon dioxide dissolved in water and diluted to 1000mL at 20 ℃ ± 5 ℃ when. After the cork tightly to save two months to
Three months.
Same isotype pH reference buffer solutions and pH buffer standard solution preparation method.
6 Instruments
6.1 measuring cell
Battery measuring apparatus shown in Figure 1. Measuring cell battery container, temperature and humidity control, platinum (palladium) hydrogen electrode, salt bridge components.
1 measuring cell device (hydrochlorothiazide has liquid junction cell)
6.1.1 battery container
A battery container made of hard glass.
6.1.2 Humidity tube
Humidity tube made of hard glass.
6.1.3 Electrode
Electrode including a hydrogen electrode two kinds of hydrogen electrode platinum and palladium. The processing method of preparation see Appendix A.
6.1.4 Salt Bridge
Preparation of a salt bridge in Appendix B.
6.2 heated water tank
Eight sets of measuring cell can be installed within the heated water tank 6.2.1.
6.2.2 thermostat bath temperature range comprising.
a) set point temperature stability (25 ℃) 8h requirements within no more than 0.1 ℃.
b) the horizontal temperature gradient field is not greater than 0.1 ℃.
c) the vertical temperature gradient field is not greater than 0.1 ℃.
6.3 Precision Thermometer
Precision thermometer with a resolution of 0.01 ℃, the maximum permissible error of 0.05 ℃. Feeding metrology department should test/calibration.
6.4 Digital Multimeter
Digital multimeter scale range (-2 ~ 2) V, maximum permissible error is 0.01mV. Feeding metrology department should test/calibration.
7 Determination
7.1 electrode, a salt bridge in Appendix A, Appendix B, pH standard buffer solution and reference buffer solution pH 5.2 by the preparation.
7.2 Battery containers and constant temperature and humidity tube through the wash, water, ultra-pure water and four dip, rinse after use.
7.3 Humidity tube was charged with slightly more than half the volume of water or test solution.
7.4 battery container and platinum (Pd) before the hydrogen electrode using a small amount of test solution was poured washed twice charged with the test solution in the battery container (cell 1,
Loading a reference buffer solution pH 3,5; 2,4,6 battery loading pH standard buffer solution), insert platinum (palladium) hydrogen electrode, installed Humidity
Tubes, then placed in a constant temperature water tank fixed, constant temperature water bath water just soaked into the measuring cell mouth, constant temperature water bath temperature to 25.0 ℃ ± 0.1 ℃.
7.5 Figure 1 connected through hydrogen into the trachea tube inlet and a tube outlet (pass to the outside).
7.6 thermostat through hydrogen, heated water tank once every 15min measuring the temperature and electromotive force. When four consecutive measurements stable electromotive force
Is within ± 0.03mV, I think balance.
Each solution should be measured eight batteries, poor battery EMF readings should be less than 0.2mV.
Off 7.7 measurement good source of hydrogen, constant temperature water bath and power carefully to measure the battery put out properly.
7.8 laboratory ambient temperature should be 15 ℃ ~ 30 ℃, relative humidity less than 80% RH.
8 Calculated
8.1 single measurement cell electromotive force to E ^ expressed by the formula (7) Calculated.
(7)
Where.
8.2 All measuring cell battery electromotive force averaged to E Yan said, according to the formula (8) Calculated.
(8)
Where.
8.3 pH standard buffer solution of pH value (pH (S) Ⅱ) according to formula (9) Calculated.
pH (S) Ⅱ = pH (S) Ⅰ +
Yan E
59.157
(9)
Where.
pH (S) Ⅰ --- pH value of the reference buffer solution of pH;
Yan E --- the average battery electromotive force, in millivolts (mV).
The precision of the method is 0.002pH, expanded uncertainty of not more than 0.01pH (k = 3). Calculation Method See Appendix C.
Appendix A
(Normative)
Platinum hydrogen electrode, hydrogen electrode preparation and processing of palladium
A. Preparation of a hydrogen electrode of platinum, palladium hydrogen electrode
Taking about 1cm2 platinum sheet, the spot on the coupling 1.5cm long platinum wire, spot welding and then coupled to the 9cm long purple copper, platinum or more sheets
Part No. 1 standard grinding mouth glass frit sealing sleeve after the plug, a copper wire coat Deutsche Bank sleeve, and the sleeve to solder copper wire bonding. Platinum hydrogen
(Palladium hydroxide) electrode structure shown in Figure A. 1.
Figure A. 1 platinum hydrogen (palladium hydroxide) electrode structure
A. Processing hydrogen electrode of platinum, palladium hydrogen electrode
A. 2.1 Preparation of the formulation
A. 2.1.1 hydrochloric acid solution of palladium chloride
Weigh 20g of palladium chloride, hydrochloric acid dissolved in 1000mL standard titration solution (1mol/L) in.
A. 2.1.2 Lead acid solution of chloroplatinic acid
Weigh 0.05g lead acetate dissolved in 1000mL chloroplatinic acid solution (30g/L) in.
A. Processing platinum hydrogen electrode 2.2
Platinum platinum hydrogen electrode sheet with hot sulfuric acid cleaning, then rinse with warm aqua regia solution (1 + 1) to washing platinum plate light (used platinum black
Electrode can be carefully wiped off with filter paper above platinum black after cleaning), then rinse with water. Wash the electrode in sulfuric acid solution (2mol/L), and
A current density of 30mA/cm2, cathode polarization 10min, platinum wire or platinum anode electrode sheet. The treated water electrode sulfuric acid wash
After the lead acetate solution of chloroplatinic acid in the plating platinum black at 180mA/cm2 under plating 40s to 1min. 40s and then plated at 120mA/cm2 to
1min (freshly prepared plating solution, plating time can be shortened more), the anode with a platinum sheet or platinum wire. Good plating electrode should be black surface uniformly fine
Dense, white spots should be washed if re-plated. Plated platinum black electrode after rinsed with water, placed in the water, washed with a magnetic stirring 10min, and then a puddle
In ultrapure water use.
A. 2.3 Processing palladium hydrogen electrode
Treatment with palladium hydrogen electrode A. 2.2. Hydrochloric acid solution of palladium chloride plating solution, the current density was 25mA/cm2 ~ 30mA/cm2,
Plating 10min, plating process should continue shaking cathode.
Appendix B
(Normative)
Preparation of the salt bridge
B. Preparation of 1-bromo-free potassium chloride
Potassium Chloride (excellent pure), dissolved in water, by removing chlorine bromine after boiling water and recrystallized once, dried at 550 ℃ high temperature furnace burning
2h ~ 3h.
B. Preparation of 2 saturated KCl Sepharose
Weigh 2g of agarose, was added 100mL of water, dissolved by heating on a hot plate, formulated as agarose gel, no added 35g chlorobromide
Potassium, formulated into a saturated potassium chloride agarose gel.
B. Preparation of the salt bridge 3
After washing and drying the battery container measuring cell, poured into saturated potassium chloride agarose gel, cooling backup in salt bridge between the two half-cell
use. Installed after comparing measured in the same electrode cell dihydrotestosterone, the force should be stable within ± 0.05mV.
Appendix C
(Informative)
pH standard buffer solution pH (S) Ⅱ Type A standard uncertainty components according to formula (C.1) Calculated.
U A [pH (S) Ⅱ] = Ju
(Yan E)
59.157 Sang-shaped
(C.1)
Where.
Experimental standard deviation Ju (Yan E) --- shape measurement result of the arithmetic mean.
Formula (C.1) in
Ju (Yan E) =
Like - Sang 1 (C.2)
pH standard buffer solution pH (S) Ⅱ Class B standard uncertainty u B component [pH (S) Ⅱ] according to equation (C.3) Calculated.
U B [pH (S) Ⅱ] = u 2 [pH (S) Ⅰ] +
ln10 · R · () T
· U 2 (E) + -F
· Yan E
ln10 · R · T () 2
· U 2 (T Sang)
(C.3)
Where.
U [pH (S) Ⅰ] --- pH buffer solution reference standard uncertainty components;
U (E) --- electromotive force standard uncertainty components;
U (T) --- temperature standard uncertainty components.
pH buffer solution reference standard uncertainty components u [pH (S) Ⅰ] according to equation (C.4) Calculation.
U [pH (S) Ⅰ] =
U [pH (S) Ⅰ]
(C.4)
Where.
U [pH (S) Ⅰ] --- expanded uncertainty pH standard reference material (pH reference material certificate is given);
--- K spreading factor (pH reference material certificate is given).
C. 2.2 electromotive force calculated standard uncertainty components
Electromotive force standard uncertainty component u (E) according to equation (C.5) Calculated.
U (E) =
U 1
Sang () 3
U 2
Sang () 3 Sang
(C.5)
Where.
U 1 --- DMM maximum permissible error, in millivolts (mV);
U 2 --- residual liquid junction potential maximum permissible error, in millivolts (mV).
C. 2.3 Temperature calculation standard uncertainty components
Temperature standard uncertainty component u (T) according to equation (C.6) Calculated.
U (T) =
U 3
Sang () 3
U 4
Sang () 3
U 5
Sang () 3 Sang
(C.6)
Where.
Temperature accuracy u 3 --- water bath, the unit is Kelvin (K);
U 4 --- precision thermometer maximum permissible error, in units of Kelvin (K);
U 5 --- precision thermometer resolution in Kelvin (K).
pH standard buffer solution pH (S) Ⅱ of the combined standard uncertainty u [pH (S) Ⅱ] according to formula (C.7) Calculated.
U [pH (S) Ⅱ] = u 2A [pH (S) Ⅱ] + u 2B [pH (S) Ⅱ Sang] (C.7)
pH standard buffer solution pH (S) Ⅱ expanded uncertainty U [pH (S) Ⅱ] according to formula (C.8) Calculated.
U [pH (S) Ⅱ] = k · u [pH (S) Ⅱ] (C.8)
Where.
U [pH (S) Ⅱ] --- pH standard buffer solution pH (S) Ⅱ of combined standard uncertainty components;
--- K coverage factor (generally k = 3).
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