The amount of stationary phase coated or bonded onto a solid support. In liquid–liquid chromatography, the amount of liquid phase in milligrams of per gram of packing. In bonded-phase chromatography, the loading may be expressed in micromoles per square meter or percentage carbon (w/w). Also called coverage or surface coverage. An alternate and unrelated meaning is the amount of sample mass injected on an analytical- or preparative-scale column; preparative-scale columns often are operated in an overloaded condition for throughput reasons.