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The Leadville Mill <br />Environmental Sampling Procedures <br />Water Sample Collection <br />Page 2 -3 <br />together. The pH meter should be calibrated with two buffer <br />solutions that most approximate the sample pH. <br />2. Thoroughly rinse a container three times with deionized water. <br />Discard the rinse water and dry the container. Then rinse the <br />container with a small amount of the appropriate buffer solution and <br />discard the rinse. Fill the container approximately 2 inches above the <br />working part of the electrode with the appropriate buffer solution. <br />3. Standardize both buffer solutions with the meter in accordance with <br />the owner's manual. <br />4. If the instrument does not calibrate for both buffers, that is the <br />instrument reads 4.0 for the 4.0 buffer and 9.9 for the 10 buffer, <br />repeat measurements until both readings are within 0.05 pH units of <br />the buffer solution value. If the calibration error is more significant, <br />see the owner's manual for troubleshooting. <br />0 pH Measurement <br />1. Keep electrodes immersed in buffer solution. Before use, remove the <br />electrodes from the buffer solution and rinse with distilled water over <br />a "wash" beaker. Dry electrode gently with soft tissue. If the electrode <br />has just been cleaned, it may need to be conditioned. Dip the <br />electrode into the sample for one minute, then blot dry and immerse <br />it into a fresh portion of the sample. <br />2. Rinse the sample container three times with deionized water then <br />wipe the container dry. Rinse the container with a small amount of <br />the sample and throw the rinse -out. Collect a sufficient amount of <br />sample to fill the container approximately 2 inches above the working <br />part of the electrode. <br />3. Immerse the electrode approximately 1 inch below the surface level of <br />the sample and keep it approximately 1 inch away from the container <br />wall. Using the electrode, stir the sample for a minimum of one <br />minute to ensure sample homogeneity. Gentle stirring will minimize <br />carbon dioxide entrapment. Take the reading when equilibrium is <br />obtained. <br />4. Note and record pH and temperature. pH values should be measured <br />to the nearest tenth of a pH value and temperature should be <br />recorded to the nearest degree centigrade. Samples may be discarded <br />following pH measurement. <br />April 2013 <br />