assay

(ăs'ā', ă-sā')

1. 1. Qualitative or quantitative analysis of a metal or ore to determine its components.
   2. A substance to be so analyzed.
   3. The result of such an analysis.
2. An analysis or examination.
3. A bioassay.
4. Archaic. An attempt; an essay.

1. 1. To subject (a metal, for example) to chemical analysis so as to determine the strength or quality of its components.
   2. To bioassay.
2. To examine by trial or experiment; put to a test: assay one's ability to speak Chinese.
3. To evaluate; assess: assayed the situation before taking action. See synonyms at estimate.
4. To attempt; try.

[Middle English, from Old French essai, assai. See essay.]

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For more information on assaying, visit Britannica.com.

noun

1. A procedure that ascertains effectiveness, value, proper function, or other quality: essay, proof, test, trial, tryout. See investigate.
2. A trying to do or make something: attempt, crack, effort, endeavor, essay, go, offer, stab, trial, try. Informal shot. Slang take. See try.

verb

1. To subject to a procedure that ascertains effectiveness, value, proper function, or other quality: check, essay, examine, prove, test, try, try out. Idioms: bring to the test, make trial of, put to theprooftest. See investigate.
2. To make a judgment as to the worth or value of: appraise, assess, calculate, estimate, evaluate, gauge, judge, rate, size up, valuate, value. Idioms: take the measure of. See value/worthlessness/evaluation.
3. To make an attempt to do or make: attempt, endeavor, essay, seek, strive, try. Idioms: have a go at, havemaketakea shot at, havetakea whack at, make a stab at, take a crack at. See try.

The act of testing the purity of precious metals.

Investopedia Says:
In futures contracts where the underlying commodities are precious metals, the quality must be assayed to ensure that they are of basis grade.

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Tutor's tip: An "assay" (examination of characteristics) following a blood test can help diagnose a disease, but can't help you with the "essay" (analytic or interpretive written composition) portion of your English test!

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!

1. the determination of the activity, potency, strength, etc. of a substance, either on an absolute basis or in comparison with that of a standard preparation.
2. the determination of the relative amount(s) of one or more components of a mixture, or of the degree of purity of a substance.
3. to carry out such a determination. See also bioassay, immunoassay, microbiological assay, radioassay.

Determination of the purity of a substance or the amount or activity of any particular constituent of a mixture.

• biological a. — bioassay; determination of the potency of a drug or other substance by comparing the effects it has in a biological system with those of a reference standard.

• Mining - assay: analysis of ore or alloy to determine proportion and purity of components; (vb) make such an analysis
• Verbs of Sight - assay: examine and evaluate

This article is about the analysis and testing of the properties of a biochemical substance. For the analysis of metals (and specifically, coins), see metallurgical assay. For the commune in the Indre-et-Loire, see Assay, Indre-et-Loire.

Look up assay in Wiktionary, the free dictionary.

An assay is a procedure in molecular biology for testing or measuring the activity of a drug or biochemical in an organism or organic sample.^[1][2] A quantitative assay may also measure the amount of a substance in a sample. Bioassays and immunoassays are among the many varieties of specialized biochemical assays. Other assays measure processes such as enzyme activity, antigen capture, stem cell activity, and competitive protein binding.

Contents 1 Assay varieties 1.1 Cytotoxicity 1.2 DNA 1.3 Protein 1.4 RNA 1.5 Cell counting, viability, proliferation or cytotoxicity assays 1.6 Surfactants 1.7 Other cell assays 1.8 Petrochemistry 1.9 Virology 1.10 Cellular secretions 1.11 Drugs 2 See also 3 References

Assay varieties

This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (May 2009)

Cytotoxicity

A cytotoxicity assay measures how toxic a chemical compound is to cells.

• MTT assay
• SRB (Sulforhodamine B) assay

DNA

Assays for studying interactions of proteins with DNA include:

• DNase footprinting assay
• Filter binding assay
• Gel shift assay

Protein

• Bicinchoninic acid assay (BCA assay)
• Bradford protein assay
• Lowry protein assay^[3][4]
• Secretion assay

RNA

• Nuclear run-on

Cell counting, viability, proliferation or cytotoxicity assays

A cell-counting assay may determine the number of living cells, the number of dead cells, or the ratio of one cell type to another, such as numerating and typing red versus different types of white blood cells. This is measured by different physical methods (light transmission, electric current change). But other methods use biochemical probing cell structure or physiology (stains). Another application is to monitor cell culture (assays of cell proliferation or cytotoxicity).

• Cell counting instruments and methods: CASY cell counting technology, Coulter counter, Electric cell-substrate impedance sensing
• Cell viability assays: resazurin method, ATP test, Ethidium homodimer assay (detect dead or dying cells), Bacteriological water analysis, Clonogenic assays, ...

Surfactants

• An MBAS assay indicates anionic surfactants in water with a bluing reaction.

Other cell assays

Many cell assays have been developed to assess specific parameters or response of cells (biomarkers, cell physiology. Techniques used to study_cells include :

• reporter assays using i.e. Luciferase, calcium signaling assays using Coelenterazine, CFSE or Calcein
• Immunostaining of cells on slides by Microscopy (ImmunoHistoChemistry or Fluorescence), on microplates by photometry including the ELISPOT (and its variant FluoroSpot) to enumerate B-Cells or antigen-specific cells, in solution by Flow cytometry
• Immunostaining of cells on slides by Microscopy, on microplates by photometry
• Molecular biology techniques such as DNA microarrays, in situ hybridization, combined to PCR, Computational genomics, and Transfection; Cell fractionation or Immunoprecipitation
• Migration assays, Chemotaxis assay
• Secretion assays
• Apoptosis assays such as Single Cell Gel Electrophoresis (Comet assay - Apoptosis DNA fragmentation), Annexin V
• Chemosensitivity assay measures the number of tumor cells that are killed by a cancer drug
• Tetramer assay detect the presence of antigen specific T-cells
• Gentamicin protection assay or survival assay or invasion assay to asses ability of pathogens (bacteria) to invade eukaryotic cells

Petrochemistry

• Crude oil assay

Virology

The HPCE-based viral titer assay uses a proprietary, high-performance capillary electrophoresis system to determine baculovirus titer.

The Trofile assay is used to determine HIV tropism.

The viral plaque assay is to calculate the number of viruses present in a sample. In this technique the number of viral plaques formed by a viral inoculum is counted, from which the actual virus concentration can be determined.

Cellular secretions

A wide range of cellular secretions (say, a specific antibody or cytokine) can be detected using the ELISA technique. The number of cells which secrete those particular substances can be determined using a related technique, the ELISPOT assay.

Drugs

• Testing for Illegal Drugs
• Radioligand binding assay

See also

• Analytical chemistry
• MELISA
• Multiplex (assay)
• Pharmaceutical chemistry
• Titration

References

1. ^ The American Heritage Dictionary of the English Language. Fourth Edition. Houghton Mifflin Company: 2000.
2. ^ McKean, Erin (ed.). The New Oxford American Dictionary. Second edition. Oxford University Press: 2005.
3. ^ Lowry OH, Rosebrough NJ, Farr AL, Randall RJ (November 1951). "Protein measurement with the Folin phenol reagent". J. Biol. Chem. 193 (1): 265–75. PMID 14907713. http://www.jbc.org/cgi/pmidlookup?view=long&pmid=14907713. 
4. ^ http://www.animal.ufl.edu/hansen/protocols/LOWRY.htm

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - probering, finhedsanalyse
v. tr. - probere, finhedsbestemme
v. intr. - probere, finhedsbestemme

Nederlands (Dutch)
het analyseren van metaal/erts, analyseerbaar materiaal, metaal/erts analyseren, goud-/zilvergehalte toetsen, pogen

Français (French)
n. - essai
v. tr. - essayer (du minerai), essayer, tenter de (arch)
v. intr. - être analysé, contenir de l'or

Deutsch (German)
n. - Probe, Analyse
v. - prüfen, analysieren

Ελληνική (Greek)
v. - δοκιμάζω, καρατάρω ή αναλύω (πολύτιμο) μέταλλο
n. - δοκιμασία, τεστ, έλεγχος καθαρότητας μετάλλου

Italiano (Italian)
esaminare

Português (Portuguese)
v. - ensaiar, testar, analisar
n. - ensaio (m), teste (m), análise (f)

Русский (Russian)
производить количественный анализ, пробовать, пытаться, испытание

Español (Spanish)
n. - prueba, ensayo
v. tr. - probar, ensayar
v. intr. - someter a prueba, probarse

Svenska (Swedish)
v. - pröva, analysera
n. - prövning, justering

中文（简体）(Chinese (Simplified))
化验, 分析, 尝试, 被验明成分

中文（繁體）(Chinese (Traditional))
n. - 化驗, 分析
v. tr. - 嘗試, 化驗, 分析
v. intr. - 被驗明成分

한국어 (Korean)
n. - 분석 시험, 시험
v. tr. - 을 분석하다, 을 시험하다, 을 평가하다
v. intr. - 금속을 함유하다

日本語 (Japanese)
v. - 分析する
n. - 分析試験, 試金

العربيه (Arabic)
‏(فعل) يجرب, يختبر, يفحص, يحلل (الاسم) اختبار, فحص, تحليل‏

עברית (Hebrew)
n. - ‮בחינת המרכיבים, האיכות והריכוז של מתכת או חומר-גלם‬
v. tr. - ‮בדק, בחן, קבע את הריכוז של‬
v. intr. - ‮הכיל שיעור מסוים של מתכת יקרה‬

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