17
3. Standard solution of 111.9 mS/cm at 25
℃
: Accurately weight
out 74.264 grams of research grade dried Potassium Chloride
(KCL). Dissolve in 1000 ml of distilled water.
[Note:
You can store the unused portion of the standard
solution in a plastic container for six months but the air space
between the cap and the solution must be kept to an absolute
minimum. Storing the excess solution below 4
℃
can increase
the storage life. If you have any doubt of the accuracy of the
stored solution, a fresh batch should be prepared.
]
