Sensor lifetime depends on a number of factors including frequency of use, storage conditions, nuances of certain sample matrices, and time between uses. Sensors are expected to last for approximately 150 runs (this includes samples, calibrations and QC checks), or for a minimum of 3-4 weeks when used consistently day after day. When analyzing higher sample concentrations (especially red range) the sensor life expectancy can be shorter, ranging from 60 – 150 total measurements depending on sample strength.
In cases where the PeCOD is not being used frequently (2 weeks or more between each set of samples), the sensor’s life expectancy timeline can be extended through the proper application of long-term storage recommendations. MANTECH recommends that when the PeCOD is not expected to be used for more than 2 weeks at a time, that Ports A and B should be primed with air, then the sensor be removed from the analyzer and stored in a dark, dry location with the sensor window face-down (white foam facing up). This is because moisture and light exposure are known to have a degrading effect on the sensor, reducing the lifespan of use. At the same time, the PeCOD Electrode Block should be removed and stored with DI water filling the internal liquid channels. This can be achieved by covering one of the channel outlets with laboratory tape, then use a syringe to inject DI water into the channel until it overflows out of the hole you are injecting into, and then cover that hole with tape as well.
When the PeCOD is being used more frequently, MANTECH recommends leaving the sensor in place with DI primed through Port A between analyses and running at least one QC check per day to keep the sensor “active” even on days that you are not expecting to run samples. This ensures the best day-to-day conditions for the sensor leading to the longest possible lifespan of use. On days where you are planning to run samples, a new calibration is recommended when the daily QC check does not fall within the +/- 20% passing range. It is always important to prime Port A and Port B x3 times with the proper reagents when going from DI water storage to the daily QC check and samples.
For more information, read MANTECH’s technical bulletin here.
