Getting pH Measurements Right: Small Cause, Large Effect: Webinar on October 9

摘要

The pH value is one of the most important and therefore also one of the most frequently measured quantities in analytical chemistry. Sometimes, a simple pH test strip is sufficient for making a rapid check; precise pH meters are, however, required whenever accurate measuring results are needed. Such a pH meter is available in practically every laboratory and is generally ready for use at a moment's notice. The measured pH value can be read off the pH meter directly and can also often be archived immediately in compliance with GLP. However, in order to verify the accuracy of the measured value, the following points should always be considered before taking a pH measurement. A pH meter is a high-resistance voltage meter. It uses an electrochemical method involving a pH glass electrode to determine the pH value of a solution. The mathematical connection between the activity a_M of an ion in solution and the potential measured at the pH electrode is described in the Nernst equation. A pH meter must meet certain prerequisites for optimum accuracy and reproducibility.