Sop for calibration of PH meter

1.OBJECTIVE

To describe the procedure for calibration and operation of PH meter.

2.SCOPE

This Standard operating Procedure is applicable to the operation and calibration of pH meter.

3.0 RESPONSIBILITY

Officer/ Executive - Quality Control

4.0 ACCOUNTABILITY

Manager - Quality Control

5.0 PROCEDURE 

5.1 Operation of pH meter 

5.1.1 first verify the instrument is on a clean and dry platform.

5.1.2 Ensure that the instrument is clean.

5.1.3 turn on the main power botton to supply the power  in the instrument.

5.1.4 Press 'ON / OFF' switch, it will display "MEAS" pH and temp." mode on the screen.

5.1.5 Ensure that the instrument is calibrated.

5.1.6 Remove the pH electrode from the storage solution and rinse it with purified water 2 to 3 times. Clean the excess purified water with tissue paper and insert the pH electrode.

5.1.7 Stir the sample solution dip the pH electrode.

5.1.8 Allow stable the pH and then record the pH in record sheet. The PH meter display shows the pH of your sample, and temperature in °C(centigrade).

5.1.9 wash the electrode with distilled water and dip the excess water with tissue paper between another sample measurements.

5.1.10 After completion of pH measurement wash the electrode and temperature sensor with the distilled water, clean the excess water with  Lint free tissue paper and insert the pH with temp. sensor electrode in the storage solution

 Note:-( prepare saturated potassium chloride solution).

5.1.11 After completion measurement enter details in using log book.

5.2 Calibration of pH meter:

5.2.1 Preparation of buffer solutions for standardization.

5.2.2 Buffer solution pH 4.01:

Dissolve 1.021 gram of potassium hydrogen phthalate in sufficient distilled water to produce 100 ml. Mix thoroughly to get uniform concentration.

Note:-(potassium hydrogen phthalate previously dried at 110°C for 2 hours).

5.2.3 Buffer solution pH 7.0:

Mix 13 ml of 2.1% w/v solution of citric acid with 87 ml of 7.15% w/v solution of disodium hydrogen phosphate.

Note:-(1.prepration of 2.1%w/v Citric acid:-

2.1gm of citric acid in 100ml volumetric flask and dilute with water and mix well.

2. Preparation of 7.15% w/v solution of disodium hydrogen phosphate:-

7.15gm disodium hydrogen phosphate in 100ml volumetric flask and dilute with water and mix well.)

5.2.4 Buffer solution pH 10.0:

Dissolve 5.4 gram of ammonium chloride in 20 ml of water, add 35 ml of 10 M ammonia and dilute with water to 100 ml and mix well.

5.2.5 Allow the instrument to stabilize for at least 15 minutes previously performing, daily calibration.

5.2.6 Tap 'CAL / MEAS' button for calibration, CAL will be display on the PH meter screen.

5.2.7 Calibrate the instrument by the using standard buffer solution alternatively of pH 4.01, 6.87 and 9.18 at  temprature 25 °C ± 2 °C.

5.2.8 Tap the 'CAL / MEAS' button, CAL will be display on the screen on PH meter. Check the standard PH of buffer Using the solution 4.01, 7.00 and 10.00 and record it.

5.2.9 Stability of buffers: 

Buffer solution shall not be stored more than 7 days. Store the buffer solution in a glass bottle or flask; use the buffer solution if the buffer solution don't observe any sedimation during the storage.

5.2.10 Storage of electrode: 

Store the electrode in saturated potassium chloride solution. Change the saturated potassium chloride solution weekly. Don't store the pH electrode in distilled water or purified water.

5.2.11 Frequency of calibration: 

Daily before use and after maintenance.

5.3 Precautions

5.3.1  when electrode is not used, then maintain the electrodes in the buffer solution of pH 7.0 + KCL (Note:-1 %w/v KCL buffer).

5.3.2 Don't wash the glass electrode bulb with any coarse material. Use only tissue paper.

5.3.3 The buffers should not get contaminated and should not be used after 7 days.

6.0 ABBREVIATIONS

6.1 SOP - Standard Operating Procedure

6.2 No. - Number

6.3 QA - Quality Assurance

6.4 NA - Not Applicable

6.5 CCF - Change control format

6.6 QC - Quality Control