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KIRTLAND AIR FORCE BASE ALBUQUERQUE, NEW MEXICO ...

KIRTLAND AIR FORCE BASE ALBUQUERQUE, NEW MEXICO ...

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APPENDIX B<br />

SOP B5.5<br />

Oxidation-Reduction Potential<br />

The following procedure is used for measuring oxidation-reduction potential:<br />

The equipment should be calibrated and its batteries checked in the laboratory before going<br />

to the field.<br />

Check that the platinum probe is clean and the platinum bond or tip is unoxidized. If dirty,<br />

polish with emery paper or, if necessary, clean the electrode using aquaregia, nitric acid, or<br />

chromic acid, in accordance with manufacturer‘s instructions.<br />

Thoroughly rinse the electrode with distilled water.<br />

Verify the sensitivity of the electrodes in accordance with the manufacturer‘s instructions.<br />

After the assembly has been checked for sensitivity, wash the electrodes with three changes<br />

of deionized water or with a flowing stream of water from a wash bottle. Place the sample in<br />

a clean glass beaker or sample cup and insert the electrodes. Set temperature compensator to<br />

the sample temperature. Provide adequate agitation throughout the measurement period.<br />

Read the millivolt (mV) potential of the solution, allowing sufficient time for the system to<br />

stabilize and reach temperature equilibrium. Measure successive portions of the sample until<br />

readings on two successive portions differ by no more than 10 mV. A system that is very<br />

slow to stabilize properly will not yield a meaningful oxidation-reduction potential. Record<br />

all results in a field log book, including oxidation-reduction potential (to nearest 10 mV),<br />

sample temperature, and pH at the time of measurement.<br />

Kirtland AFB<br />

SOPs for Field Investigations B-133 April 2004

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