Most everyone working with Karl Fischer Titration at some point ends up wanting to check their instrument for accuracy and overall operational readiness. Karl Fischer Water Standards were made to assist operators with making these operational checks. Sometimes however we find there is some confusion about the choice of water standards available and what the numbers mean.
Hydranal water standards provide a few popular choices for both coulometric and volumetric Karl Fischer Titrators:
- Hydranal 0.1 (100PPM ±10% error acceptance)
- Hydranal 1.0 (1,000PPM ±3% error acceptance)
- Hydranal 10.0 (10,000PPM)
So what do the numbers mean? 0.1, 1.0, 10.0?
Simply put, these numbers tell us the amount of moisture (H2O) that is present in 1 gram of the water standard. The amount of moisture (H2O) is expressed as milligrams on the packaging. Using the Hydranal 1.0 for example we say there is 1.0 milligram of moisture (H2O) in 1 gram of the water standard. Did you know there are 1,000 micrograms per 1.0 milligram? Yes there is. So instead of thinking in terms of 1 milligram per 1 gram of water standard, think in terms of 1,000 micrograms per 1 gram of water standard. Why?
Karl Fischer Titrators count moisture in micrograms!
Since Karl Fischer Titrators count moisture in micrograms it's easier to think about the water standards in terms of micrograms. Why?
We evaluate our water standard test in PPM
For the Hydyanal 1.0 we are looking for results within ±3% of 1,000PPM (970PPM to 1030PPM). For the Hydranal 0.1 we are looking for results within ±10% of 100PPM (90PPM to 110PPM).
Don't forget this formula!:
PPM = WATER DETECTED IN MICROGRAMS/SAMPLE SIZE IN GRAMS
(For those who don't know PPM stands for Parts Per Million)
We hope this information has been helpful.