1. n. [Drilling Fluids]

On a weight per volume basis, the SI unit of concentration, abbreviated mg/L, usually applied to dissolved material in a solution. This unit is used in water analyses and in mud and mud-filtrate analyses. Increasingly, mg/L and ppm are used interchangeably in mud analyses. Actually, mg/L and ppm can only be interchanged when the sample has the exact density of water, which is only approximated by very dilute solutions.

See: API,  dissolved solids,  epm,  ppm