What does the abbreviation "ca." refer to when it is placed before a unit of measurement?

Document ID

Document ID TE3784

Version

Version 2.0

Status

Status Published

Published Date

Published Date 27/05/2017
Question
What does the abbreviation "ca." refer to when it is placed before a unit of measurement?
Summary
The abbreviation "ca." when used with a unit of measurement.
Answer
The abbreviation "ca." is short for "circa" which means approximately.

For example, in the Diacetyl, Vicinal Diketone (VDK), method 2023 it says to add ca. 0.5 g of naphthol solution in 100 ml of isopropanol. This means that approximately 0.5 g of naphthol solution need to be added to 100 ml of isopropanol.