STANDARD OPERATING PROCEDURE

Page 2 of 4

Effective Date: Oct 2003

Document Ref: PROD.P.007

STANDARD OPERATING PROCEDURE

FOR

OPERATION OF pHS-25 pH METER

DOCUMENT REFERENCE: PROD.P.007

Written by: KELECHI .O. ATUONWU Date: OCTOBER 2007Approved by: _______________________ Date ; ________

Review Period

3 years

Expiry Date

Oct 20101. PURPOSE

For the safe and effective use and operation of the pHS -25 pH meter which is used to measure the power of Hydrogen ion concentrations of any given aqueous solution in the laboratory.

2. RESPONSIBILITIES

1. It is the responsibility of the QA Laboratory Analyst to ensure that the following procedure is fully implemented.2. It is the responsibility of the QA Laboratory Analyst to ensure that the equipment is kept in the right operating standard always and that procedures are being followed.

3.It is the responsibility of QA Laboratory Analyst to ensure that this procedure is followed strictly and any deviation reported immediately to the Q. A. Manager.

3. REFERENCES

pHS-25 pH meter operating manual.

4. DEFINITIONSiD.C. ; Direct current

ii.A/D ; Analogue Digital.

5. PROCEDURE

OPERATIONAL REQUIREMENT

i. Ambient Temperature;0 - 400 Cii. Relative Humidity;50 85%iii. Solution Temperature;5 - 60oC

iv. Power Supply; 220v, 50Hz.

MAIN PARAMETERS

i. pH;0 14.00 pH(measuring range)

ii.Range of temperature compensation; 0 - 60oC

iiiPower consumption ;1W

ivWeight ;3 Kg

vInput Impedance; 5 x 1011 viAccuracy ; pH 0.1pH

PRINCIPLE OF OPERATION

The pH meter is based on a D.C. potential generated by a pH combination electrode. The D.C. potential is fed to an A/D converter via a preamplifier for digital display of pH values.START UP CHECKSI Confirm correct connection of electrode terminal to the meter.

ii.Confirm electrode is mounted on the electrode holder.iii.Confirm equipment is clean.

v. Confirm equipment is placed on a vibration free workbench. START UP

STANDARDIZATION

1.Switch on the equipment.

2.Select the selection knob to pH position.3.Set the slope position to 100%.4.Rinse the electrode with distilled water, and clean with tissue paper.

5.Put the electrode into the buffer solution of known pH (e.g. pH value 4.0)

6.Adjust the temperature regulator; stir the solution in the beaker until it is uniform.

7.Adjust the setting potentiometer, to set the reading displayed on the meter the same as the pH value of the buffer solution.

8.Record your readings in the calibration notebook.

9.Repeat steps 3 8 for buffer solutions of pH value 7.0, 10.0 respectively.

10.Once standardization is complete, its setting potentiometer should not be changed anymore. The meter once standardized it could be used to measure the pH of a solution at once.Note; during the time at which the meter is not in use, the bulb of the electrode should be immersed in distilled water.

pH VALUE MEASUREMENT

(A)In case the temperature of the solution to be measured is the same as the temperature of the setting solution.i.Move the electrode clamp upward and remove it.

ii.rinse the end of the electrode with distilled water and clean it with tissue paper

iii.Put the electrode into the solution to be measured, stir the solution till it is uniform

iv.Read out and record the pH value of the solution.

(B)In case the temperature of the solution to be measured is different from the temperature of the setting solution.

i.Move the electrode clamp upward and remove it.

ii.Rinse the end of the electrode with distilled water and clean with a tissue paper.iii.Measure the temperature of the solution to be measured with a thermometer.

iv.Adjust the temperature regulator to the measured temperature value of the solution.

v.Put the electrode into the solution to be measured, stir the solution until it is uniform.

vi.Read out and record the pH value of the solution.

RE-STANDARDIZATION

It is necessary to re standardize the meter in compliance with the standardization procedure in case any of the following conditions occurs;

i.The electrode has been dried for too long.

ii.The electrode is a newly replaced one.

iii.The setting potentiometer has changed.

iv.After measuring an Acidic solution or Alkaline solution of high concentration.

v.After measuring an organic solution of high concentration.

vi.The temperature of the solution is largely different from the temperature at the time of standardization. MAINTENANCE i.The meter should be cleaned daily.

ii.The meter should be placed on a vibration free workbench.iii.The buffer solutions been used to standardize the pH meter should be of high reliability.iv.Servicing and replacement of component parts should be done by certified maintenance personnel.

.

6. HEALTH AND SAFETYI. Wear proper safety wears- hand glove, Lab coat etc.

II. Ensure that connected terminals are functioning.III. Dont put hand under electrode bulb.

IV. Power off the equipment before attempting any repair/cleaning on the equipment.

7. CHANGE HISTORY

Nil.

PAGE \# "'Page: '#''" Insert a brief description of the SOP including limitations

PAGE \# "'Page: '#''" Detail the Job Functions responsible for any requirements and for the operation of the SOP

PAGE \# "'Page: '#''" List any SOPs used as reference in the format NUMBER ; NAME : (Current Issue)

PAGE \# "'Page: '#''" Include definitions of terms and phrases used to assist in the understanding of the SOP

PAGE \# "'Page: '#''" Detailed procedure but not too wordy and try to keep in work order.

PAGE \# "'Page: '#''" Enter the dates and notes about previous revisions.

C:\Documents and Settings\QANALYST\My Documents\SOP PH METER..doc