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Buffer solution

di-sodium hydrogen phosphate/potassium dihydrogen phosphate, traceable to NIST, traceable to PTB, pH 6.86 (25 °C), Certipur®


traceable to NIST
traceable to PTB

Quality Level

product line



di-sodium hydrogen phosphate/potassium dihydrogen phosphate


6.86 (25 °C)

storage temp.


General description

The potassium dihydrogen phosphate/di-sodium hydrogen phophate buffer solution is gravimetrically prepared at a registered calibration laboratory with high-quality reagents and water. Its pH value of 6.86 at 25°C is measured using a combined glass electrode following a 5-point calibration method. The measurement is made following DIN 19268 using reference buffer solutions compliant to DIN 19266, NIST, IUPAC, Ph. Eur, and USP. The buffer pH is temperature dependent and therefore a constant temperature must be maintained during its use.


The buffer is used as a standard to calibrate pH measuring instruments or pH electrodes and as a control to measure the pH of other solutions.


500 ml in Plastic bottle

Features and Benefits

  • Measured and qualified at an ISO/IEC 17025 and ISO 17034 accredited laboratory
  • Traceable to secondary reference standard from NIST and primary certified reference standard from PTB
  • Available in a secure 500 mL plastic bottle to prevent contamination
  • Accompanied with a detailed and batch-specific certificate of analysis (CoA) for an effective audit
  • Product label follows the ISO Guide 31 and contains information about ordering number, article description, lot number, safety data, and expiry date
  • Packaging material subjected to comprehensive stability studies as per ISO Guide 35
  • An uncertainty of +/- 0.02 in the pH value at 25°C

Legal Information

CERTIPUR is a registered trademark of Merck KGaA, Darmstadt, Germany

Storage Class Code

12 - Non Combustible Liquids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Certificate of Analysis

Enter Lot Number to search for Certificate of Analysis (COA).

Certificate of Quality

Enter Lot Number to search for Certificate of Quality (COQ).

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