Handling of volumetric flasks
What are volumetric flasks?
Volumetric flasks, class A and B, are calibrated to contain (TC, In), and are mainly used for the preparation of highly accurate dilutions and standard solutions.
Modern analytical methods require small-capacity volumetric flasks. Small-sized conventional volumetric flasks (up to approx. 50 ml) tend to tip over easily due to their high center of gravity and their small base area. Trapezoidal volumetric flasks are much more stable. Their center of gravity is lower, and their base area is more than twice as large compared to the equivalent standard flasks.
How to prepare a standard solution with a volumetric flask
1. Insert the precisely weighed amount of substance, or rinse in a standard solution concentrate.
2. Fill the flask with distilled water to about half. Swirl the flask to dissolve and mix the contents thoroughly.
3. Top up the flask with distilled water to just below the ring mark.
4. Top up the remaining volume, using a wash bottle or pipette, until the meniscus is exactly at the ring mark. Important: meniscus must be read at eye level. The wall of the flask must not be wetted above the mark.
5. Close the flask and shake upside down to mix contents.
