Where does precipitation collide?

In chemistry, precipitation is the formation of an insoluble solid, the precipitate, that separates from a solution once the concentration of its ions exceeds what the solvent can hold, a limit set by the solubility product Ksp. LaMer and Dinegar's 1950 Theory, Production and Mechanism of Formation of Monodispersed Hydrosols described how a solution driven past saturation nucleates and grows solid particles, laying out the mechanism by which a precipitate forms. The referent is a phase change in a beaker, a dissolved species becoming a solid, and it has nothing to do with rain falling from the sky, a stressor that triggers an illness, or an antibody pulling a protein out of a lysate.[1]

Unit

A solid phase separating from a saturated solution, governed by Ksp

Recovery means

The precipitate can redissolve if the solution is diluted or the ion product falls back below the solubility product

Measured by

Assessed by the mass of solid recovered by filtration and by comparing the ion product against the tabulated solubility product

In meteorology and hydrology, precipitation is water in any form, rain, drizzle, snow, sleet, or hail, that condenses in the atmosphere and falls to the Earth's surface, the wet arm of the water cycle. Trenberth, Dai, Rasmussen, and Parsons's 2003 The Changing Character of Precipitation examined its amount, frequency, intensity, and type, and how those properties are shifting as the climate warms. The referent is a flux of water reaching the ground, recorded as a depth over time, and it is unrelated to a solid forming in a solution, a trigger for a disorder, or an assay that captures an antigen.[2]

Unit

Water falling to the surface, as a depth in millimetres over a period

Recovery means

Not applicable

Measured by

Gauged as accumulated depth by rain gauges, and estimated over area by weather radar and satellite retrieval

In psychiatry and clinical medicine, a precipitating factor, or precipitant, is the proximate event that triggers the onset of a disorder or episode in a person who already carries an underlying vulnerability, the stress term in the diathesis-stress or vulnerability-stress framework. Zubin and Spring's 1977 Vulnerability: A new view of schizophrenia set out how a stressful challenge can precipitate an episode once it crosses an individual's threshold of vulnerability. The referent is a triggering event in a clinical history, distinguished from the predisposing diathesis, and it bears no relation to a solid dropping out of solution, rain reaching the ground, or an antibody-based purification.[3]

Unit

A triggering event that crosses a vulnerability threshold to onset an episode

Recovery means

Not applicable

Measured by

Identified from the clinical history and life-event interviews that time a stressor to the onset of symptoms

In immunology and biochemistry, immunoprecipitation is a technique that uses an antibody to bind a specific target protein and pull it out of a complex solution, so the antigen is precipitated, usually onto beads, and separated from everything else for analysis. DeCaprio and Kohl's 2017 Immunoprecipitation protocol described how antibody, antigen, and a solid support are combined and washed to isolate the target and any partners bound to it. The referent is a laboratory purification driven by antibody specificity, not the bulk phase change of a chemical precipitate, water falling as weather, or a stressor that triggers an illness.[4]

Unit

A target antigen captured from a lysate by a specific antibody on a support

Recovery means

The captured antigen is released from the antibody and support by elution before it is analysed

Measured by

Detected after elution by gel electrophoresis, immunoblot, or mass spectrometry of the isolated protein