Complete Guidance on pH Meter Principle and Guidance.
pH Meter is one of the essential and basic instruments in the World of Analytical Chemistry. The pH instrument uses to measure the pH of various solutions. The pH Principle, Working Principle of the pH meter, Calibration as per USP, care, and maintenance are illustrated below.
pH Meter Principle and Definition
The pH is defined as the negative logarithm of the hydrogen ion concentration. The pH was first introduced by the Danish Scientist “Soren Peder Lauritz Sorensen” in 1909.
pH is a measure of the relative amount of free hydrogen and hydroxyl ions in the water. Hence, Water with more free hydrogen ions considers acidic, whereas Water with more free hydroxyl ions considers basic.
pH full form
The full form of the “pH” is called “Potential of Hydrogen”. pH is a scale to measure the acidity or basicity in a solution.
pH scale / pH Range
pH is a measure of acidity/basic in a solution. The pH scale or the pH range starts from 0 – 14. A pH scale of 7 indicates neutral, a pH less than 7 indicates acidity, and a pH scale greater than 7 indicates a base.
pH of Water
Pure water shows a pH of 7 hence considered “neutral” because it is neither acidic nor basic qualities.
pH of Blood
Blood is normally slightly basic, with a normal pH range of 7.35 to 7.45
pH meter working principle/ pH Instrument
The pH meter is an electric device that measures the “Hydrogen-ion activity (acidity or alkalinity) of a solution. pH instrument consists of a voltmeter connected to a pH-responsive electrode (Glass electrode) and a reference electrode, which measure the voltage between two pH electrodes and displays the pH reading/ pH result. The pH meter was invented by “Arnold O. Beckman”.
The pH Meter requirements as per the USP General chapter was provided below.
pH meter Calibration
The calibration of the pH meter is performed by submerging the pH electrode (sensor) into the respective pH buffers (calibration buffers) of known pH values. USP <791> states that a minimum of two buffers for calibration and One buffer for pH verification.
pH measurement as per USP 791
The USP <791> contains guidance on pH measurement, instrumentation specifications, and usage. The USP guidance provides tips and tricks on how to meet the requirements.
pH meter care and maintenance
To improve the pH measurement accuracy, repeatability, and reliability of results, the below best practices shall implement at Laboratory.
Properly maintain the pH Buffer care, Buffer disposal, pH measurement practice, electrode maintenance, probe storage, cleaning of the electrode, regeneration, and lifetime of the electrode.
Read other articles only at PharmaeliX. Importance of ALCOA Plus 9 Principles, Good HPLC Practices for accurate analysis
Trackbacks/Pingbacks