Operation, Calibration and Maintenance of Eutech pH Meter, Model : pH 2700.

1.0 OBJECTIVE 

To lay down the procedure for Operation, Calibration and Maintenance of Eutech pH Meter, Model : pH 2700.

2.0 SCOPE

This SOP is applicable for the Operation, Calibration, and Maintenance of the Eutech pH Meter, Model: pH 2700 in the Company Name

3.0 BACKGROUND

NIL

4.0 RESPONSIBILITY

4.1 All Analytical Research personnel shall follow the SOP.

4.2 Group leader Analytical Research department to ensure proper and safe operation of the equipment.

4.3 Head Analytical Research or his designee to ensure overall compliance.

5.0 PROCEDURE

5.1 Safety Precautions

5.1.1 Use gloves and goggles while operating the equipment. 

5.1.2 Wash the electrode carefully only with de-ionized water.

5.1.3 Ensure the electrode is placed into 3M KCL solution. 

5.1.4 Buffer temperature should be maintained at 25ºC+/-2ºC.

5.1.5 Handle the pH electrode ( glass electrode ) carefully.

5.2 Operating Procedure

5.2.1 Switch ON the main power supply and switch ON equipment. 

5.2.2 Ensure the pH Meter is calibrated before Usage.

5.2.3 Wash the electrode number of times with Type-1 water before and after Usage.

5.2.3 Wipe the electrode gently with clean tissue paper without any traces.

5.2.4 Dip the pH electrode (glass electrode) in the solution for measurement. And note the pH value after stabilization (Value in Bold ).

5.3 Calibration procedure  

5.3.1 Starting pH calibration

5.3.1.1 Turn the meter ON

5.3.1.2 Rinse the electrode and temperature probe in in deionized water. Wipe with clean tissue paper.

5.3.1.3 Take pH buffers 1.68, 4.01, 6.86, 9.18 and pour into the clean beakers. Temperature of buffers should be maintained at 25 ±1 ºC.

5.3.1.4 Entering the calibration mode takes pH 6.86  (neutral buffer).

5.3.1.5 Dip the electrode and temperature probe into the calibration buffer.

5.3.1.6 The electrode bulb and temperature probe must be completely immersed into the sample. 

5.3.1.7 The upper display will flash pH until the reading has stabilized. 

5.3.1.8 When pH reading has stabilized press ENTER. The lower display flashes pH offset Cal done, this calibration point is now stored in the pH meter.

5.3.1.9 Same procedure  shall be followed with the buffers 1.68, 4.01, 9.18     

5.3.2  Acceptance Criteria :

Slope ----- 90 to 105%

Offset ------ ± 30mV

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Offset value =

Electrode potential generated with buffer 6.86 = -15mV (example) 

This is taken as Offset value 

Slope calculation:

Example 1 =

Electrode potential generated with buffer 4.01 = 145mV

slope value of a buffer = 

The difference in mV from 4.01 and 6.86 buffers= 145-(-15)  = 160 mv

The pH difference from 6.86 and 4.01 =2.85

= 160/2.85 = 56.14

Measured Slope value = 56.14

Then 

Slope value% = Slope value measured / Ideal slope value x100

Ideal slope value per 1 pH unit scale = 59.16

Then 56.14/59.16x 100 =94.89 %

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Example 2 =

Electrode potential generated with buffer 9.18 = 118mV

slope value of a buffer = 

The difference in mV from 6.86 and 9.18 buffers= 118-(-15)  = 133 mv

The pH difference from 6.86 and 9.18 =2.32

= 133/2.32 = 57.33

Measured Slope value =57.33

Then 

Slope value% = Slope value measured / Ideal slope value x100

Ideal slope value per 1 pH unit scale = 59.16

Measured Slope value =57.33

Then 57.33/59.16x 100 

=96.90%

Acceptance Limits for Slope are 90 to 105%

5.3.3 After completion of the four-point calibration press ESC button and then pH meter automatically return to measurement mode. 

5.3.4  After completion of the calibration ensure the pH meter is in measurement mode.

5.3.5 Clean the electrode and temperature probe with type-1 water and wipe with clean tissue paper

5.3.6 Take the buffer of pH 1.68 and dip the electrode and temperature probe, wait until the reading has stabilized, and note the stabilized value.

5.3.7 Same procedure will follow the 4.01, 6.86, and 9.18 buffers wait until the reading has stabilized and note down the stabilized value.

5.3.8 Acceptance Criteria:

Measured value shall be within ± 0.05

5.4 Measurement of the pH of the sample solutions

5.4.1 Before Measurement of the sample solution ensure Daily calibration was done. 

5.4.2 After completion of the calibration ensure the pH meter in to the measuring mode.

5.4.3 Clean the electrode and temperature probe with type-1 water and wipe the tissue with tissue paper.

5.4.4 Dip the electrode and temperature probe in to the sample solution and wait until the  reading has stabilized.

5.4.5 After completion of the sample pH measurement wash the electrode and temperature probe.

5.4.6 Place and Store the electrode in 3M KCL Solution. 

5.5  Maintenance

Maintenance shall be done by service engineer or external vendor.

6.0 VERSION HISTORY

7.0 ANNEXURES