Editing Plate reader (section)

===Absorbance===
Absorbance detection has been available in microplate readers for more than 3 decades and is used for assays such as [[ELISA]] assays, protein and nucleic acid quantification or enzyme activity assays<ref name="Mohamed-Bassem">{{cite journal |last1=Ashour |first1=Mohamed-Bassem A. |last2=Gee |first2=Shirley J. |last3=Hammock |first3=Bruce D. |title=Use of a 96-well microplate reader for measuring routine enzyme activities |journal=Analytical Biochemistry |date=November 1987 |volume=166 |issue=2 |pages=353–360 |doi=10.1016/0003-2697(87)90585-9 |pmid=3434778 }}</ref> (i.e. in the [[MTT assay]] for cell viability).<ref name="pmid6606682">{{cite journal |last1=Mosmann |first1=Tim |title=Rapid colorimetric assay for cellular growth and survival: Application to proliferation and cytotoxicity assays |journal=Journal of Immunological Methods |date=December 1983 |volume=65 |issue=1–2 |pages=55–63 |doi=10.1016/0022-1759(83)90303-4 |pmid=6606682 }}</ref> A light source illuminates the sample using a specific wavelength (selected by an optical filter, or a monochromator), and a light detector located on the other side of the well measures how much of the initial (100%) light is transmitted through the sample: the amount of transmitted light will typically be related to the concentration of the molecule of interest.  Several conventional [[colorimetric]] analyses have been miniaturized to function quantitatively in a plate reader, with performance suitable for research purposes.  Examples of analyses converted to plate reader methods include several for [[ammonium]], [[nitrate]], [[nitrite]],<ref>{{cite journal |last1=Sims |first1=G. K. |last2=Ellsworth |first2=T. R. |last3=Mulvaney |first3=R. L. |title=Microscale determination of inorganic nitrogen in water and soil extracts |journal=Communications in Soil Science and Plant Analysis |date=11 November 2008 |volume=26 |issue=1–2 |pages=303–316 |doi=10.1080/00103629509369298 }}</ref> [[urea]],<ref>{{cite journal |last1=Greenan |first1=N.S. |last2=Mulvaney |first2=R.L. |last3=Sims |first3=G. K. |title=A microscale method for colorimetric determination of urea in soil extracts |journal=Communications in Soil Science and Plant Analysis |date=11 November 2008 |volume=26 |issue=15–16 |pages=2519–2529 |doi=10.1080/00103629509369465 |url=https://zenodo.org/record/1234433 }}</ref> iron(II),<ref>{{cite journal |last1=Tor |first1=Jason M. |last2=Xu |first2=Caifen |last3=Stucki |first3=Joseph M. |last4=Wander |first4=Michelle M. |last5=Sims |first5=Gerald K. |title=Trifluralin Degradation under Microbiologically Induced Nitrate and Fe(III) Reducing Conditions |journal=Environmental Science & Technology |date=August 2000 |volume=34 |issue=15 |pages=3148–3152 |doi=10.1021/es9912473 |bibcode=2000EnST...34.3148T }}</ref> and [[orthophosphate]].<ref>{{cite journal |last1=D'Angelo |first1=Elisa |last2=Crutchfield |first2=J. |last3=Vandiviere |first3=M. |title=Rapid, Sensitive, Microscale Determination of Phosphate in Water and Soil |journal=Journal of Environmental Quality |date=November 2001 |volume=30 |issue=6 |pages=2206–2209 |doi=10.2134/jeq2001.2206 |pmid=11790034 }}</ref> More recent colorimetric chemistries have been developed directly for use in plate readers.<ref>{{cite journal |last1=Rhine |first1=E. D. |last2=Mulvaney |first2=R. L. |last3=Pratt |first3=E. J. |last4=Sims |first4=G. K. |title=Improving the Berthelot Reaction for Determining Ammonium in Soil Extracts and Water |journal=Soil Science Society of America Journal |date=1998 |volume=62 |issue=2 |pages=473 |doi=10.2136/sssaj1998.03615995006200020026x |bibcode=1998SSASJ..62..473R }}</ref>