{{Short description|Chemical test}} '''Spot analysis''', '''spot test analysis''', or a '''spot test''' is a chemical test, a simple and efficient technique where analytic assays are executed in only one, or a few drops, of a chemical solution, preferably in a great piece of filter paper, without using any sophisticated instrumentation. The development and popularization of the test is credited to Fritz Feigl.<ref>[https://books.google.com/books/about/Spot_tests_in_organic_analysis.html?id=nK7QAAAAMAAJ "Spot tests in organic analysis"], numerous editions</ref><ref name=bull>{{cite journal|url = http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/num17-18/num17-18%20p31-39.pdf|title = Fritz Feigl (1891-1971): The Centennial of a Researcher|first1 = Aida|last1 = Espinola|first2 = Mario A.|last2 = da Silva Pinto|first3 = Claudio|last3 = Costa Neto|journal = Bull. Hist. Chem.|volume = 17/18|year = 1995|pages = 31–39}}</ref>
'''Spot test''' or '''spot assay''' can also refer to a test often used in microbiology.
==Chemistry== The foundations of Feigl's work on spot analysis were the works of Hugo Schiff (the earliest publication about "spot test" was Shiff's detection of uric acid in 1859<ref>H. Schiff, ''Ann. Chim. Acta'', 1859, 109, 67.</ref>) and of Christian Friedrich Schonberg and Friedrich Goppelsröder on capillary analysis.<ref name=bull/>
On the occasion of Feigl's 70th birthday the Chemical Society of Midland sponsored a symposium in 1952, attended by 500 scientists from 24 countries, in which all plenary sessions were related to spot tests.<ref name=bull/>
The test uses the qualitative characteristics of colored compounds to account for performed chemical reactions. This technique has been used to develop new quantification methods using modern technology.<ref>{{cite journal|last1=Soares|first1=Samara|last2=Lima|first2=Manoel J.A.|last3=Rocha|first3=Fábio R.P.|title=A spot test for iodine value determination in biodiesel based on digital images exploiting a smartphone|journal=Microchemical Journal|volume=133|pages=195–199|doi=10.1016/j.microc.2017.03.029|year=2017}}</ref>
==Microbiology== [[File:Spot assay yeast cells.jpg|thumb|Spot assay of yeast cells on an agar plate. The spots show either growth (cells) or no growth (no cells)]] thumb|96 pinner used to perform spot assays with yeast or bacterial cells A spot assay or spot test can also refer to a specific test in microbiology. This test is often used to check the growth rate of bacterial or yeast cells on different media or to perform serial dilution tests of micro-organisms. Usually a 96-pinner (often called frogger) is used to perform these spot assay. Another application is high-throughput screening, whichoften uses spot assays to determine the growth of eg. mated cells or to check for protein-protein interactions in a yeast two-hybrid test. This is often done with a robot.<ref name="Thomas">{{cite journal|last1 = Thomas|first1 = Pious|last2 = Shekhar|first2 = Aparna C.|last3 = Upreti|first3 = Reshmi|last4 = Mujawar|first4 = Mohammad M.|last5 = Pasha|first5 = Sadiq S.|title = Optimization of single plate-serial dilution spotting (SP-SDS) with sample anchoring as an assured method for bacterial and yeast cfu enumeration and single colony isolation from diverse samples|journal = Biotechnology Reports|volume = 8|pages = 45–55|year = 2015|pmid = 28352572|doi = 10.1016/j.btre.2015.08.003|pmc=4980700}}</ref>
==See also== *Spot test (lichen) *Touchstone
==References== {{Reflist}}
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Category:Chemical tests Category:Analytical chemistry Category:Measurement Category:Brazilian inventions