How often should I replace an Ammonia ISE's membrane module?
Membrane replacement schedule.
A membrane module will last from one week to several months depending on the usage and sample matrix. Shifts in potential, measurement drift, poor response or failed calibration are signs that the membrane should be replaced. Also, replace the membrane module if dark spots or discoloration are seen with visual inspection. Avoid excessive handling of membrane modules or direct contact with membrane surface as this can affect the membrane’s hydrophobic properties, causing shorter membrane life. This is true for any Ammonia probe that uses a gas permeable membrane.