An Introduction to pH Buffer Solutions

If you are interested in carrying out reliable pH measurements, then you are probably well-versed in the differences between acids and bases. However, the fundamentals are important to emergent areas of pH metrology and the importance of pH buffer solutions so we will recap the basics briefly.

Accurate pH Measurements with Buffer Solutions

Formally, the pH value of a substance denotes the negative logarithm of hydrogen ion activity. This is sometimes referred to as the potential, or power, of hydrogen in an aqueous solution. The pH of a solution is expressed on a scale of 0–14 and it is a temperature-dependent property. Pure water, for instance, is largely neutral with a pH of 7.47 at 0°C and 6.14 at 100°C.

Measuring the pH value of a solution is typically done using a potentiometer which – theoretically – produces a 0 millivolt (mV) differential between a sensing and reference electrode at pH 7. Any change in acidity or alkalinity changes the electrode output, providing an accurate electrochemical basis for estimating the pH value. We say estimate here as your measurement device is only as accurate your as pH buffer solution.

What is a pH Buffer Solution?

A pH buffer solution, sometimes referred to as a hydrogen ion buffer, is an aqueous solution with a traceable pH value which changes negligibly when mixed with small volumes of strong acids or bases. Generally, pH buffers are composed of a mixture of a conjugate base with a weak acid which can absorb excess hydrogen atoms to maintain a stable pH value in solution. They are subsequently ideal for calibrating electrochemical potentiometers for low uncertainty pH measurements with greater traceability.

This is increasingly important as more and more chemists buy into the NIST framework of pH metrology, building an unbroken chain of reliability from the standard reference material (SRM) manufacturer through to the end-user. Today, NIST-traceable pH buffers set the benchmark for reliability in pH measurements across the broadest possible spectrum of applications, with uncertainties approaching values as small as 0.01 pH units.

Looking for pH Buffer Solutions?

Inorganic Ventures is one of the industry’s leading suppliers of NIST-traceable certified reference materials (CRMs) for pH measurements and analytical chemistry. We specialise in generating custom solutions for specific client workflows, providing full documentation to ensure complete accountability and reliability. If you are looking for pH buffer solutions certified via direct comparison to NIST SRMs, why not contact a member of the team today?

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