What is "gravimetric analysis"

Gravimetric \Grav"i*met"ric\, a. (Chem.) Of or pertaining to measurement by weight; measured by weight. -- Grav"i*met"ric*al*ly, adv.

Gravimetric analysis (Chem.), analysis in which the amounts of the constituents are determined by weight; -- in distinction from volumetric analysis.

n. (context analytical chemistry English) Any of several methods and techniques of analytical chemistry in which the amount of a substance in a sample is determined by weighing a precipitate, filtrate, residue etc after some physical or chemical process.

n. quantitative analysis by weight

Gravimetric analysis describes a set of methods in analytical chemistry for the quantitative determination of an analyte based on the mass of a solid. A simple example is the measurement of solids suspended in a water sample: A known volume of water is filtered, and the collected solids are weighed.

In most cases, the analyte must first be converted to a solid by precipitation with an appropriate reagent. The precipitate can then be collected by filtration, washed, dried to remove traces of moisture from the solution, and weighed. The amount of analyte in the original sample can then be calculated from the mass of the precipitate and its chemical composition.

In other cases, it may be easier to remove the analyte by evaporation. The analyte might be collected—perhaps in a cryogenic trap or on some absorbent material such as activated carbon—and measured directly. Or, the sample can be weighed before and after it is dried; the difference between the two masses gives the mass of analyte lost. This is especially useful in determining the water content of complex materials such as foodstuffs.