Calibration of pH Meter in Quality Assurance B.Pharmacy 6th Semester
CALIBRATION OF pH METER
B.PHARMACY 6TH SEMESTER
INTRODUCTION
A pH meter is an electronic instrument used for measuring the pH (acidity or alkalinity) of a liquid (though special probes are sometimes used to measure the pH of semi-solid substances). A typical pH meter consists of special measuring probes (a glass electrode and a reference electrode) connected to an electronic meter that measures and displays the pH reading. SDPGIPS Rohtak
PRINCIPLE
pH is defined as the negative logarithm of hydrogen ion concentration.
pH= -log [ H+ ]
p = power
H = hydrogen
[H+ ] = hydrogen ion concentration
The pH of a solution can be measured by the pH meter. The glass electrode is an half cell and the calomel electrode is another half cell. SDPGIPS Rohtak
WHAT IS CALIBRATION
Calibration is the act of ensuring that a method or instrument used in measurement will produce accurate results. Calibration is performed using primary reference standard. SDPGIPS Rohtak
NEED OF CALIBRATION
When a specific time period is elapsed. When a specific operating hours has elapsed. With a new instrument. When observations appear questionable. SDPGIPS Rohtak
PARTS OF DIGITAL PH METER
pH electrode Device have 4 knobs SDPGIPS Rohtak
FUNCTION MODE
Function Mode, pH Mode, (used to measure pH by rotation), Standby mode, MV Mode (used to measure mv) • Temperature settling knob: To set temperature • Calibration knob: rotate to adjust and set Ph value to standard pH value. SDPGIPS Rohtak
PROCEDURE
First of all, calibrate the pH meter. & prepare standard buffer solition of pH 4 and ph 7 (calibratin by standard buffer solution of pH7). First dip electrode in standard buffer solution of pH 7. Then set temperature at 25°c by rotating temperate knob. Rotate the function knob to pH mode. And wail for constant display reeding. Rotate calibration Knob to the right display reading become 7. Rotate function knob to standby mode and Remove electrode from solution. Then rinse electrode with distilled water and dry it with tissue paper. SDPGIPS Rohtak
PROCEDURE
Calibrate the pH meter. & prepare standard buffer solution of pH 4 and pH 7 (calibration by standard buffer solution of pH4). First dip electrode in standard buffer solution of pH 4. Then set temperature at 25°c by rotating temperate knob. Rotate the function knob to pH mode. And wail for constant display reeding. Rotate slope Knob to the right display reading become 4. Rotate slope knob to standby mode and Remove electrode from solution. Then rinse electrode with distilled water and dry it with tissue paper. SDPGIPS Rohtak
Thank you.