Buffer solutions – working standards рН of 2<sup>nd</sup> category
Intended for
reproducing and transmitting the activity index of hydrogen ions (pH) in aqueous solutions; verification and calibration of рН measuring instruments according to GOST 8.120-2014 of controlling the metrological characteristics when tested, and for type approval; error control of measurement procedures (MP) рН of liquid media.
Buffer solutions are aqueous solutions of chemicals. Solutions reproduce values of activity of hydrogen ions. Buffer solutions are contained in plastic bottles. The bottle is leakproof and has a screw cap with a protective ring. Buffer solutions have 9 modifications, that differ by concentration of chemicals and reproducible values
Limits of permissible absolute accuracy of рН reproduction:
| in the temperature range from + 5 to + 20°С | ±0,02 |
| in the temperature range from + 20 to + 40°С | ±0,01 |
| in the temperature range from + 40 to + 80°С | ±0,02 |
| Bottle volume | 125 см3, 270 см3 |
| Expiry date | 1 year. |
| Marking of buffer solutions | Marking of buffer solutions | Chemical formula of substances | Substance concentration | рН reproducible value at temperature +25°С |
|---|---|---|---|---|
| BR-рН-1 | Potassium tetraoxalate dihydrate | KH3(C2O4)2·2H2O | 0,1 | 1,48 |
| BR-рН-2 | Potassium tetraoxalate dihydrate | KH3(C2O4)2·2H2O | 0,05 | 1,65 |
| BR-рН-3 | Potassium hydrogenphthalate | KНC8H4O4 | 0,05 | 4,01 |
| BR-рН-4 | Potassium phosphate monosubstituted Sodium phosphate twice-substituted |
KH2PO4 Na2HPO4 |
0,025 0,025 |
6,86 |
| BR-рН-5 | Potassium phosphate monosubstituted Sodium phosphate twice-substituted |
KH2PO4 Na2HPO4 |
0,0087 0,0304 |
7,41 |
| BR-рН-6 | Potassium phosphate monosubstituted Sodium phosphate twice-substituted | Na2B4O7·10H2O |
0,01 0,04 |
7,43 |
| BR-рН-7 | Sodium tetraborate decahydrate | Na2B4O7·10H2O | 0,01 | 9,18 |
| BR-рН-8 | Sodium tetraborate decahydrate | Na2B4O7·10H2O | 0,05 | 9,18 |
| BR-рН-9 | Sodium carbonate Sodium carbonate acid |
Na2CO3 NaHCO3 |
0,025 0,025 |
10,00 |
For verification and calibration of working measuring instruments in research institutions, analytical laboratories рН.
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