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SOP NUMBER 8.0 <br />Page 8 of 10 <br />Field Parameter Measurements <br />Attachment 1 <br />Calibration of Powertech Field Instruments <br />1.1 pH Meter <br />Calibration will consist of the following general procedures: <br />1. The meter will be calibrated using the conventional to point calibration method "ConCal." <br />An admissible standard solution will be used: Buffer solution pH 7.0 +/- 0.5 and a buffer <br />solution pH 4.0 +/- 0.5. <br />2. Press the CAL button until you see pH, ASY and the temperature on the screen of the meter. <br />Also at the bottom should appear an icon labeled Cal in small print. <br />3. Immerse pH electrode into a neutral buffer solution. pH value of the solution: 7.0 +/- 0.5. <br />Then press the button RUN/ENTER on the meter. <br />4. Set pH value of the buffer solution using the up and down arrows on the meter. CHECK <br />THE TEMPERATURE OF THE BUFFER SOLUTION! ! The specific pH value required <br />based on the temperature is on the side of the bottle of the buffer solution. <br />Next press the RUN/ENTER. You will get an indication of asymmetry. The admissible <br />range is +/- 30mV. <br />6. Press the RUN/ENTER button again. You should see pH, SLO, and the temperature on the <br />screen of the meter. Rinse the pH electrode and immerse into the second buffer solution (pH <br />4.0). <br />7. Next press RUN/ENTER again. <br />8. Set pH value of the buffer solution using the up and down arrows on the meter. CHECK <br />THE TEMPERATURE OF THE BUFFER SOLUTION! ! The specific pH value required <br />based on the temperature is on the side of the bottle of the buffer solution. <br />9. Next press RUN/ENTER again. You will get a slope range on the screen. The admissible <br />slope range is -50mV/pH to -62.OmV/pH. <br />10. Next press RUN/ENTER again. You will get the indication offset voltage asymmetry. The <br />admissible range is +/- 30mV. <br />11. Now check the readings (+0.1 pH units) for all the buffers used for calibration. <br />12. Your meter is now ready for calibration of conductivity. <br />Note: Always use the same electrode for measurements that was used in the calibration. <br />Recalibrate the meter if the electrode is replaced. Also, the temperature setting on the pH meter <br />often does not match the sample temperature after calibration. The pH readings will be accurate <br />in these cases provided that the response to the buffers is correct. <br />Record the time and temperature in the field logbook whenever the pH meter is calibrated. <br />Powertech <br />4123/2007 <br />Rev SOP 8-1 JAB <br />8-8 <br />R Squared Inc <br />?