A lab should standardize their pH meter with standard buffers prior to use each work shift. However, it is really dependent on who is overseeing the lab’s quality program. It is recommended that you either contact your State or Region (if the Region is responsible for certifying the lab) and request guidance on that issue.
I am interested if the US EPA has a requirement on pH Meter Calibration QA/QC. If so, I would like to know the procedure. Specifically, I would like to know if the US EPA requires a duplicate pH analysis be analyzed once every ten samples.
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