pH Buffer Solutions (4, 7 and 9)

€10.95 *
Content: 0.1 Litre (€109.50 * / Litre)

* Prices incl. VAT
plus potential shipping costs

Ready to ship, arrives in 2 - 5 days

Free Shipping from €33 within DE per GLS

Unit Size:

pH Value:

  • Z0030100
  • 4260169961505
  • 0.11 kg
  • 4.00 cm × 11.00 cm × 4.00 cm
For Calibration of pH Combination Electrodes (standardized to 20 °C) Why calibrate/adjust... more
Product information »pH Buffer Solutions (4, 7 and 9)«

For Calibration of pH Combination Electrodes (standardized to 20 °C)

Why calibrate/adjust

The electronics of the pH meter must be adapted to the special characteristics of the pH meter used by calibration. Not only different meters vary from each other (zero point, slope), but the same meter also changes due to ageing processes.
Precise and reproducible PH measurements are therefore only possible when calibration is carried out regularly and carefully.

The frequency of this procedure naturally depends on the place of use and the purpose. If measurement is carried out under greatly changing conditions, calibration is recommended before every measurement.
In the case of constant measurement in the aquarium, it is sufficient to calibrate every 2 - 4 weeks if nothing else has changed. A new meter or one at the end of its service life will change to a greater degree and therefore calibration will be necessary more often than in the middle of the expected service life.

Selection of the buffers

For two-point calibration, the two buffer solutions are selected in such a way that the pH to be measured is between the values of the two buffers where possible.
The ability to calibrate pH 4 and pH 9 to cover the whole pH range is only seemingly advantageous. Due to non-linearities of the meter and of the measuring amplifier, however, it leads to significant errors.

Temperature-dependence of the pH at various temperatures

As can be seen, it is very important to observe the correct temperature during calibration.

TemperatureBuffer pH 4Buffer pH 7Buffer pH 9
0 °C 4.03 7.13 9.24
10 °C 4.02 7.05 9.11
20 °C 4.00 7.00 9.00
30 °C 4.00 6.98 8.93
40 °C 4.00 6.97 8.86
50 °C 4.00 6.96 8.80
60 °C 4.00 6.96 8.75
70 °C 4.00 6.97 8.71
80 °C 4.00 6.98 8.67
90 °C 4.00 7.00 8.64

Handling buffer solutions

To ensure exact calibration, buffer solutions must be handled carefully. All dirt is to be avoided.
Therefore, never pour buffer solutions back into the storage bottle or calibrate directly in the storage bottle. Used buffer solutions are disposed of and not used a second time.

In the case of alkaline buffer solutions (pH > 7), the CO2 in the air causes a gradual neutralisation of the buffer. The storage bottles should therefore be resealed as soon as possible after use and contact with air reduced to a minimum.

Composition of the buffer solutions offered

pH 4 (20 °C) d204 = 1.007 (~ 0.056 m citric acid solution / ~ 0.068 m NaOH solution / ~ 0.044 m NaCl solution)

pH 7 (20 °C) d204 = 1.006 (~ 0.029 m NaOH solution / ~ 0.050 m KH2PO4 solution)

pH 9 (20 °C) d20 4 = 1.001 (~ 0.013 m Na2B4O7 solution / ~ 0.0046 m HCl solution)

(NaOH - sodium hydroxide, NaCl - sodium chloride, KH2PO4 - potassium dihydrogen phosphate, Na2B4O7 - sodium borate or borax, HCl - hydrochloric acid)

The solutions and chemicals used are non-toxic (at least in small quantities). Nevertheless, the electrodes should be thoroughly rinsed with demineralised water before being re-used in the aquarium. The buffers and rinsing solution can be poured directly down the drain without reservations.

Related links to »pH Buffer Solutions (4, 7 and 9)«
Read, write and discuss reviews... more
Customer evaluation for "pH Buffer Solutions (4, 7 and 9)"
Write an evaluation
Evaluations will be activated after verification.
Please enter these characters in the following text field.

The fields marked with * are required.

Please note our Data Protection Declaration.

Potassium chloride solution 3 molar 50 ml Potassium chloride solution for redox and pH combination...
0.05 Litre (€105.00 / Litre)
From €5.25 *
Calibration Solution Conductivity 1413 µS/cm Calibration Solution Conductivity 1413 µS/cm
0.05 Litre (€119.00 / Litre)
From €5.95 *
Ferrdrakon Full Iron Fertilizer 0.25 l bottle Ferrdrakon Full Iron Fertilizer
0.25 Litre (€33.80 / Litre)
From €8.45 *
KramerDrak 0.5 l bottle KramerDrak Special Iron Complete Fertilizer for Strong...
0.25 Litre (€42.60 / Litre)
From €10.65 *
Duradrakon 100 g Tin Duradrakon Hardener Salt
0.1 kg (€82.00 / kg)
From €8.20 *
Zuebi Grower-Bits Zuebi - Grower-Bits with Spirulina and Krill
0.15 Litre (€46.33 / Litre)
From €6.95 *
Potassium chloride solution 3 molar 50 ml Potassium chloride solution for redox and pH combination...
0.05 Litre (€105.00 / Litre)
From €5.25 *
Eudrakon N 250 ml Bottle Eudrakon N Nitrogen Fertilizer Solution
0.25 Litre (€33.80 / Litre)
From €8.45 *
Duradrakon TH-Plus 100 g Tin Duradrakon TH-Plus Hardener Salt Mixture
0.1 kg (€119.50 / kg)
From €11.95 *
Daydrakon Daily Fertilizer & Iron Fertilizer 1.0 l Bottle Daydrakon Daily & Iron Fertilizer
0.25 Litre (€33.80 / Litre)
From €8.45 *
Zueflo Flakes Zueflo - Grower-Flakes with Spirulina and Octopus
0.15 Litre (€29.67 / Litre)
From €4.45 *
Zuesti Sticks Zuesti - Grower-Sticks with Spirulina and Krill
0.15 Litre (€46.33 / Litre)
From €6.95 *
Aquadrakon Black 250 ml Bottle Aquadrakon Black Water Conditioning
0.25 Litre (€42.60 / Litre)
From €10.65 *
Granulated Black Peat Standard Granulated Black Peat Standard
0.5 Litre (€10.30 / Litre)
From €5.15 *
Eudrakon P Phosphate Fertilizer 1.0 l Bottle Eudrakon P Phosphate Fertilizer
0.5 Litre (€13.38 / Litre)
From €6.69 *
Pepsin based cleaning solution bottles Pepsin based cleaning solution - Protein remover
0.05 Litre (€119.00 / Litre)
From €5.95 *
Terrdrakon Substrate 250 g Terrdrakon Substrate
0.25 kg (€29.20 / kg)
From €7.30 *
Aquadrakon EL 0.25 l Bottle Aquadrakon EL Water Conditioning
0.25 Litre (€33.80 / Litre)
From €8.45 *
FD Bloodworms FD Bloodworms / Stand-up Pouch(es)
0.025 kg (€278.00 / kg)
From €6.95 *
Calibration Solution Conductivity 1413 µS/cm Calibration Solution Conductivity 1413 µS/cm
0.05 Litre (€119.00 / Litre)
From €5.95 *
Decapsulated Artemiacysts Bags Decapsulated Artemiacysts / Stand-up Pouch
0.05 kg (€159.00 / kg)
From €7.95 *
NEW
Ferrdrakon K Full Potassium Fertilizer 0.5 l Bottle Ferrdrakon K Full Potassium Fertilizer
0.25 Litre (€42.60 / Litre)
From €10.65 *
Phosphareduc 100 g Package Phosphareduc Phosphate Fixer
0.1 kg (€49.50 / kg)
From €4.95 *
Diaphragm cleaner with thiourea bottles Cleaning solution with thiourea - Diaphragm cleaner
0.05 Litre (€119.00 / Litre)
From €5.95 *
Granulated Black Peat Micro Granulated Black Peat Micro
0.5 Litre (€8.58 / Litre)
From €4.29 *
Chlorella Micro Algae Granulate Chlorella Micro Algae Granulate made in Germany
0.05 kg (€159.00 / kg)
From €7.95 *
Spirulina Mikro Algae Powder Spirulina Micro Algae Powder
0.05 kg (€99.00 / kg)
From €4.95 *
Chlorella Micro Algae Powder Chlorella Micro Algae Powder (Chlorella vulgaris)
0.05 kg (€139.00 / kg)
From €6.95 *
Bactedrakon Bottles Bactedrakon - filter bacteria
0.1 Litre (€99.90 / Litre)
From €9.99 *
pH/CH-Minus 250 ml Bottle DRAK pH/CH-Minus - pH and KH easily and quickly lowered
0.25 Litre (€33.40 / Litre)
From €8.35 *
Hint!
Check Solution for CO₂ Long-term Tests Check Solution for CO₂ Long-term Tests
0.1 Litre (€79.50 / Litre)
From €7.95 *
Hint!
High-performance Filter Material Fibalon® plus High-performance Filter Material Fibalon® plus
0.05 kg (€145.00 / kg)
From €7.25 *
FD Bloodworms FD Bloodworms / Tin
0.15 Litre (€46.33 / Litre)
From €6.95 *
Duradrakon 100 g Tin Duradrakon Hardener Salt
0.1 kg (€82.00 / kg)
From €8.20 *
Zueflo Flakes Zueflo - Grower-Flakes with Spirulina and Octopus
0.15 Litre (€29.67 / Litre)
From €4.45 *
Hint!
Fulvodrakon - Concentrated Fulvic and Humic acids 100 ml Fulvodrakon - Concentrated Fulvic and Humic acids
0.1 Litre (€79.50 / Litre)
From €7.95 *
Daydrakon Daily Fertilizer & Iron Fertilizer 1.0 l Bottle Daydrakon Daily & Iron Fertilizer
0.25 Litre (€33.80 / Litre)
From €8.45 *
filtAS filter filling material 500 ml filtAS filter filling material 500 ml
0.5 Litre (€6.00 / Litre)
€3.00 *
Granulated Black Peat Micro Granulated Black Peat Micro
0.5 Litre (€8.58 / Litre)
From €4.29 *
Hint!
Sealutions Mineral Salt 1 kg Tin Sealutions Mineral Salt
1 kg
From €19.95 *
Visidrakon 50 ml Visidrakon - Water Clarifier
0.05 Litre (€119.00 / Litre)
From €5.95 *
Catappa bark piece XL - model 1 Catappa bark pieces XL
€4.99 *
P for 198 points
Bactedrakon Bottles Bactedrakon - filter bacteria
0.1 Litre (€99.90 / Litre)
From €9.99 *
Aquadrakon EL 0.25 l Bottle Aquadrakon EL Water Conditioning
0.25 Litre (€33.80 / Litre)
From €8.45 *
Aquadrakon Black 250 ml Bottle Aquadrakon Black Water Conditioning
0.25 Litre (€42.60 / Litre)
From €10.65 *
Viewed