Calibration Solutions
- Thread starter Timinator
- Start date
From what I can gather...
1. Salinity standards -
According to OSIL, the company responsible for IAPASO standard seawater, for highly accurate work the solution is maintained in a borosilicate bottle without extremes in temperature (8-25 C) the recommended shelf life is 96 weeks but has been shown to be relatively stable out to 3 years. However, this assumes the bottle is not opened and completed used once opened.
A number of factors are thought to affect the long-term stability of standard seawater. These include microbial activity and interactions between the seawater and the glass. Salinity standards for the aquarium industry are stored in, I believe, polyethylene bottles. Opening and closing it you also run the risk of further contamination and evaporation. In addition if you are sticking a conductivity probe in it, the risks also include dilution/contamination with whatever water you use to rinse your probe with as well as the aquarium microbes on the probe. American Marine states that their 53mS calibration fluid can be reused if kept in a tightly sealed container, presumable to limit evaporation, but do not give a shelf life.
From all this what can you conclude for long term salinity standards given aquarists require less accuracy than oceanographers? I believe if you don't contaminate the bottle, such as sticking a probe into it, or leave it open for a prolonged time you should get 2-3 years out of it.
2. pH standards -
For pH standards in a bottle from which you pour an aliquot for calibration, the shelf life is usually on the bottle but from what I gather they are good for 1 year.
Shelf life for the single use packs I think the shelf life should be stamped on the pouch.
1. Salinity standards -
According to OSIL, the company responsible for IAPASO standard seawater, for highly accurate work the solution is maintained in a borosilicate bottle without extremes in temperature (8-25 C) the recommended shelf life is 96 weeks but has been shown to be relatively stable out to 3 years. However, this assumes the bottle is not opened and completed used once opened.
A number of factors are thought to affect the long-term stability of standard seawater. These include microbial activity and interactions between the seawater and the glass. Salinity standards for the aquarium industry are stored in, I believe, polyethylene bottles. Opening and closing it you also run the risk of further contamination and evaporation. In addition if you are sticking a conductivity probe in it, the risks also include dilution/contamination with whatever water you use to rinse your probe with as well as the aquarium microbes on the probe. American Marine states that their 53mS calibration fluid can be reused if kept in a tightly sealed container, presumable to limit evaporation, but do not give a shelf life.
From all this what can you conclude for long term salinity standards given aquarists require less accuracy than oceanographers? I believe if you don't contaminate the bottle, such as sticking a probe into it, or leave it open for a prolonged time you should get 2-3 years out of it.
2. pH standards -
For pH standards in a bottle from which you pour an aliquot for calibration, the shelf life is usually on the bottle but from what I gather they are good for 1 year.
Shelf life for the single use packs I think the shelf life should be stamped on the pouch.
Some pH standards are off even before expiration. I would not use one without an expiration data.
Salinity standards will last forever in the absence of significant evaporation.
I'm new with all of this.... what is a calibration solution, what does it do, and where can you get it?
If you have a pH or salinity measuring device, especially if electronic, calibration standards can help ensure they are functioning accurately.
Salinity standards will last forever in the absence of significant evaporation.
I'm new with all of this.... what is a calibration solution, what does it do, and where can you get it?
If you have a pH or salinity measuring device, especially if electronic, calibration standards can help ensure they are functioning accurately.
The pouches are certainly a good way to go. I detail some good brands here:
A Comparison of pH Calibration Buffers
http://reefkeeping.com/issues/2005-02/rhf/index.htm
A Comparison of pH Calibration Buffers
http://reefkeeping.com/issues/2005-02/rhf/index.htm
:thumbsup:
Happy Reefing.
Happy Reefing.
