millieqL

millieqL is a nominal unit of chemical concentration used to express the amount of electric charge in solution per liter. It is defined as one thousandth of an equivalent per liter (0.001 eq/L).

Origin and scope: The term arose in the 2010s during discussions of ion-concentration standards, notably within a consortium known as the International Hydration and Electrochemistry Society. It was proposed as a descriptor for charge-based concentration measurements in contexts such as water treatment, soil science, and electrochemical research.

Definition and relation to other units: millieqL is defined as 0.001 equivalents per liter. In practice, it is numerically equivalent to the conventional milliequivalents per liter (meq/L). For a dissolved species with molarity c (mol/L) and charge z, the charge concentration is c × z × 1000 millieqL.

Applications and example: In environmental monitoring and electrolyte formulation, millieqL provides a concise expression of ionic charge concentration. Example: 0.01 mol/L Ca2+ (z = 2) has 0.02 eq/L, i.e., 20 millieqL.

Status and reception: The unit remains uncommon and is not widely standardized; many practitioners rely on meq/L. Advocates argue for official standardization to avoid ambiguity, while critics caution that introducing a new name may fragment communication across fields.

See also: meq/L; equivalents; ionic strength.