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ph_measurement_tips [27/06/2019 13:08] pieter |
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===== FAQ ===== | ===== FAQ ===== | ||
//**How often do I need to calibrate my pH meter? | //**How often do I need to calibrate my pH meter? | ||
- | This depends on the type of products being measured, the maintenance and the required accuracy. It may be weekly, daily or before each use or set of uses.\\ | + | This depends on the type of products being measured, the maintenance and the required accuracy. It may be weekly, daily or before each use or set of uses. See [[http:// |
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//**If measuring the entire range of pH what buffers should be used?**//\\ | //**If measuring the entire range of pH what buffers should be used?**//\\ | ||
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* The electrode mV in a pH 4 buffer (at 25°C) should be 160 to 180 mV more than the value in pH 7. | * The electrode mV in a pH 4 buffer (at 25°C) should be 160 to 180 mV more than the value in pH 7. | ||
* The electrode mV in a pH 10 buffer (at 25°C) should be 160 to 180 mV less than the value in pH 7. | * The electrode mV in a pH 10 buffer (at 25°C) should be 160 to 180 mV less than the value in pH 7. | ||
- | * If the mV values are outside of the above ranges, clean the pH electrode. If cleaning does not return the mV to an acceptable range, replace the electrode. Note: as long as the pH electrode has a slope between 92% and 102%, the electrode should be working properly. The pH buffers should be replaced if the measured mV values are outside of the acceptable ranges. Contaminated buffers may slightly contribute to shifted mV values. | + | * If the mV values are outside of the above ranges, clean the pH electrode. If cleaning does not return the mV to an acceptable range, replace the electrode. Note: as long as the pH electrode has a slope between 92% and 102%, the electrode should be working properly. The pH buffers should be replaced if the measured mV values are outside of the acceptable ranges. Contaminated buffers may slightly contribute to shifted mV values.\\ |
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//**My pH electrode is drifting. What should I do?**//\\ | //**My pH electrode is drifting. What should I do?**//\\ | ||
There are three possible causes for electrode drift: | There are three possible causes for electrode drift: |