What is the best way to standardize my Karl Fischer titrant?
For standardizing Karl Fischer reagents one would expect the best standard to be pure water. Water, however, does not satisfy the requirements of a primary standard in that it is not stable during weighing and does not have a high enough molecular weight. The second point raises the problem of accurately weighing a sufficiently small sample so as to give a reasonable titrant consumption. As an alternative to pure water, certified standard solutions can be obtained in various concentrations ranging from 0.1mg to 10mg water per g (or per mL). This allows the weighing out of a more suitable sample size. A third possibility is to use a solid sample with exactly known water content. The most common standard here is sodium tartrate dihydrate. This standard contains two waters of crystallization giving it a water content of exactly 15.66%. The advantage of this standard is that it is available as a finely ground powder with a stable and guaranteed water content. Since the water content is onl
