View source for Coomassie brilliant blue

{{Distinguish|Brilliant blue FCF}}
{{chembox
| verifiedrevid = 455133631
|Name=Coomassie Brilliant Blue R-250
|ImageFile = Coomassie Brilliant Blue R-250.svg
|ImageSize = 250px
|ImageAlt = Skeletal formula of Coomassie brilliant blue R-250
|ImageFile1 = Coomassie Brilliant Blue zwitterion 3D spacefill.png
|ImageSize1 = 250
|ImageAlt1 = Space-filling model of the coomassie brilliant blue R-250 molecule
|IUPACName=
|OtherNames=[[Colour Index International|C.I.]] 42660, C.I. Acid Blue 83<br/>Brilliant indocyanine 6B, Brillantindocyanin 6B<br/>Brilliant Cyanine 6B, Serva Blue R
|Section1= {{Chembox Identifiers
| index1_label = acid
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo=6104-59-2
| ChEMBL = 4279842
| ChemSpiderID1 = 21172997
| EC_number = 228-060-5
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = TKL1K0PT9A
|  PubChem=61365
| StdInChI=1S/C45H45N3O7S2.Na/c1-4-47(31-33-9-7-11-43(29-33)56(49,50)51)40-23-15-36(16-24-40)45(35-13-19-38(20-14-35)46-39-21-27-42(28-22-39)55-6-3)37-17-25-41(26-18-37)48(5-2)32-34-10-8-12-44(30-34)57(52,53)54;/h7-30H,4-6,31-32H2,1-3H3,(H2,49,50,51,52,53,54);/q;+1/p-1
| StdInChIKey = NKLPQNGYXWVELD-UHFFFAOYSA-M
|  SMILES = CCN(CC1=CC(=CC=C1)S(=O)(=O)O)C2=CC=C(C=C2)C(=C3C=CC(=[N+](CC)CC4=CC(=CC=C4)S(=O)(=O)[O-])C=C3)C5=CC=C(C=C5)NC6=CC=C(C=C6)OCC.[Na+]
  }}
|Section2= {{Chembox Properties
|  Formula=C<sub>45</sub>H<sub>44</sub>N<sub>3</sub>NaO<sub>7</sub>S<sub>2</sub> (Sodium salt)
|  MolarMass=825.97 g/mol
|  Appearance=
|  Density=
|  MeltingPt=
|  BoilingPt=

|  Solubility=Insoluble in cold, slightly soluble in hot (bright red blue)
|  SolubleOther= Slightly soluble
|  Solvent=ethanol
  }}
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{{chembox
|Name=Coomassie brilliant blue G-250
|ImageFile1=Coomassie Brilliant Blue G-250.svg
|ImageSize1=250px
| ImageFileL1 = Sample of Coomassie Brilliant Blue G.jpg
| ImageSizeL1 = 130
| ImageCaptionL1 = Solid Coomassie brilliant blue G
| ImageFileR1 = Coomassie Brilliant Blue G in Isopropanol.jpg
| ImageSizeR1 = 130
| ImageCaptionR1 = Brilliant blue G in isopropanol solution
|IUPACName=
|OtherNames=[[Colour Index International|C.I.]] 42655, C.I. Acid Blue 90<br/>Brilliant indocyanine G, Brillantindocyanin G<br/>Xylene Brilliant Cyanine G, Serva Blue G
|Section1= {{Chembox Identifiers
|  CASNo=6104-58-1
|  PubChem=6324599
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = D10799
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  }}
|Section2= {{Chembox Properties
|  Formula=C<sub>47</sub>H<sub>50</sub>N<sub>3</sub>NaO<sub>7</sub>S<sub>2</sub> (Sodium salt)
|  MolarMass=856.03 g/mol
|  Appearance=
|  Density=
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|  Solubility=Slightly soluble in cold, soluble in hot (bright blue)
|  SolubleOther= Soluble
|  Solvent=ethanol
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'''Coomassie brilliant blue''' is the name of two similar [[triphenylmethane]]  dyes that were developed for use in the textile industry but are now commonly used for [[staining]] [[protein]]s in [[bioanalytical chemistry|analytical biochemistry]]. Coomassie brilliant blue G-250 differs from Coomassie brilliant blue R-250 by the addition of two [[methyl group]]s. The name "Coomassie" is a [[registered trademark]] of [[Imperial Chemical Industries]].

==Name and discovery==
The name Coomassie was adopted at the end of the 19th century as a trade name by the [[Blackley]]-based dye manufacturer [[Levinstein Ltd]], in marketing a range of [[acid dye|acid wool dyes]].<ref>{{ cite book | last = Fox | first = M. R. | year = 1987 | title = Dye-makers of Great Britain 1856-1976 : A History of Chemists, Companies, Products and Changes | publisher = Imperial Chemical Industries | location = Manchester | page = 38 }}</ref> In 1896 during the [[Anglo-Ashanti wars#Fourth Anglo-Ashanti War, 1895 - 1896|Fourth Anglo–Ashanti War]], British forces had occupied the town of Coomassie (modern-day [[Kumasi]] in [[Ghana]]). In 1918 Levinstein Ltd became part of British Dyestuffs, which in 1926 became part of Imperial Chemical Industries.<ref>{{ cite book | last = Fox | first = M. R. | year = 1987 | title = Dye-makers of Great Britain 1856-1976 : A History of Chemists, Companies, Products and Changes | publisher = Imperial Chemical Industries | location = Manchester | page = 259 }}</ref>  Although ICI still owns the Coomassie trademark, the company no longer manufactures the dyes.

The blue disulfonated triphenylmethane dyes were first produced in 1913 by Max Weiler, who was based in [[Elberfeld]], Germany.<ref>{{cite book | year = 1971 | title = Colour Index | edition = 3rd | volume = 4 | pages = 4397–4398 | publisher = Society of Dyers and Colourists | location = Bradford | url = http://www.colour-index.org/help/3121_Triarylmethane.pdf | access-date = 2010-07-20 | archive-url = https://web.archive.org/web/20110719160728/http://www.colour-index.org/help/3121_Triarylmethane.pdf | archive-date = 2011-07-19 | url-status = dead }}</ref> Various patents were subsequently taken out on the organic synthesis.<ref>{{ cite patent | status = patent | assign1 = Bayer | title = Procédé de production de colorants de la série du triarylméthane | gdate = 1915-02-16 | number = 474260 | country = FR }}</ref><ref>{{ cite patent | status = patent | inventor1-last = Weiler | inventor1-first = Max | title = Blue Triphenylmethane Dye | gdate = 1917-03-06  | number = 1218232 | country = US }}</ref><ref>{{ cite patent | status = patent | assign1 =  IG Farbenindustrie | title = Manufacture of Triarylmethane-dyestuffs | gdate = 1927-11-03 | number = 275609 | country = GB }}</ref>

Papers published in biochemistry journals frequently refer to these dyes simply as "Coomassie" without specifying which dye was used. In fact, the [[Colour Index International|Colour Index]] lists over 40 dyes with "Coomassie" in their name. There are also other Coomassie "blue" dyes. For example, the [[Merck Index]] (10th edition) lists Coomassie Blue RL (Acid Blue 92, C.I. 13390), which has a completely different structure.

==Dye colour==
The suffix "R" in the name of Coomassie brilliant blue R-250 is an abbreviation for "red" as the blue colour of the dye has a slight reddish tint. For the "G" variant the blue colour has a more greenish tint. The "250" originally denoted the purity of the dye.

The colour of the two dyes depends on the acidity of the solution. The "G" form of the dye has been studied in detail.<ref name=chial>{{cite journal | last1 = Chial | first1 = H. J. | last2 = Thompson | first2 = H. B. | last3 = Splittgerber | first3 = A. G. | year = 1993 | title = A spectral study of the charge forms of Coomassie Blue G | journal = Analytical Biochemistry | volume = 209 | pages = 258–266 | doi = 10.1006/abio.1993.1117 | issue = 2 | pmid = 7682385 }}</ref> At a [[pH]] of less than 0 the dye has a red colour with an absorption maximum at a wavelength of 465&nbsp;nm. At a pH of around 1 the dye is green with an absorption maximum at 620&nbsp;nm while above pH&nbsp;2 the dye is bright blue with a maximum at 595&nbsp;nm. At pH&nbsp;7 the dye has an [[Molar absorptivity|extinction coefficient]] of 43,000&nbsp;M<sup>−1</sup>&nbsp;cm<sup>−1</sup>.<ref name=chial/>

The different colours are a result of the different charged states of the dye molecule. In the red form, all three nitrogen atoms carry a positive charge. The two sulfonic acid groups have extremely low [[Acid dissociation constant|p''K''<sub>a</sub>]] and will normally be negatively charged, thus at a pH of around zero the dye will be a [[cation]] with an overall charge of +1. The green colour corresponds to a form of the dye with no net overall charge. In neutral media (pH&nbsp;7), only the nitrogen atom of the [[diphenylamine]] [[Functional group|moiety]] carries a positive charge and the blue dye molecule is an [[anion]] with an overall charge of −1. The p''K''<sub>a</sub> values for the losses of the two protons are 1.15 and 1.82, respectively. The final proton is lost under alkaline conditions and the dye becomes pink (p''K''<sub>a</sub> 12.4).<ref name=chial/>

The dye interacts electrostatically but noncovalently with the amino and carboxyl groups of proteins. The dye molecules bind to proteins, including those in wool ([[keratin]]), to form a protein–dye complex. The formation of the complex stabilises the negatively charged anionic form of the dye, producing the blue colour, even under acid conditions when most of the molecules in solution are in the cationic form.<ref name=chial/>  This is the basis of the [[Bradford assay]], which quantifies protein by Coomassie brilliant blue dye binding. The binding of the dye to a protein causes a shift in the absorbance maximum of the dye from 465 to 595&nbsp;nm. The increase of absorption at 595&nbsp;nm is monitored to determine protein concentration.<ref>{{cite journal | last=Bradford | first=Marion M. | year=1976 | title=A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding | journal=Analytical Biochemistry | volume=72 | issue=1–2 | pages=248–254 | doi=10.1016/0003-2697(76)90527-3 | url=http://hoffman.cm.utexas.edu/courses/bradford_assay.pdf | pmid=942051| s2cid=4359292 }}</ref>

The dye also forms a complex with the anionic detergent [[Sodium lauryl sulfate|sodium dodecylsulfate]] (SDS).<ref>{{ cite journal | last1 = Compton | first1 = S. J. | last2 = Jones | first2 = C. G. | year = 1985 | title = Mechanism of dye response and interference in the Bradford protein assay | journal = Analytical Biochemistry | volume = 151 | pages = 369–374 | doi = 10.1016/0003-2697(85)90190-3 | issue = 2 | pmid = 4096375 }}</ref> The formation of this complex stabilizes the neutral, green form of the dye. This effect can interfere with the estimation of protein concentration using the Bradford assay. It is also likely that the anionic detergent competes with the dye for binding to the protein.

==Applications in biochemistry==
Coomassie brilliant blue R-250 was first used to visualise proteins in 1963 by Fazekas de St. Groth and colleagues.  Protein samples were separated electrophoretically on a [[cellulose acetate]] sheet. The sheet was then soaked in [[sulfosalicylic acid]] to fix the protein bands and transferred to a solution of the dye.<ref>{{ cite journal | last1 = Fazekas de St. Groth | first1 = S. | last2 = Webster | first2 = R. G. | last3 = Datyner | first3 = A. | year = 1963 | title = Two new staining procedures for quantitative estimation of proteins on electrophoretic strips | journal = Biochimica et Biophysica Acta | volume = 71 | pages = 377–391 | pmid = 18421828 | doi = 10.1016/0006-3002(63)91092-8 }}</ref>

Two years later in 1965 Meyer and Lambert used Coomassie brilliant blue R-250 to stain protein samples after electrophoretic separation in a [[polyacrylamide gel]]. They soaked the gel in a dye solution containing [[methanol]], [[acetic acid]] and water. As the dye stained the polyacrylamide gel as well as the protein, in order to visualise the protein bands they needed to destain the gel, which they did electrophoretically.<ref>{{ cite journal | last1 = Meyer | first1 = T. S. | last2 = Lambert | first2 = B. L. | year = 1965 | title = Use of Coomassie brilliant blue R250 for the electrophoresis of microgram quantities of parotid saliva proteins on acrylamide-gel strips | journal = Biochimica et Biophysica Acta (BBA) - General Subjects | volume = 107 | pages = 144–145 | doi = 10.1016/0304-4165(65)90403-4 | pmid = 4159310 | issue = 1 }}</ref> Subsequent publications reported that polyacrylamide gels could be successfully destained using an acetic acid solution.

The first report of the use of the G form of the dye to visualise protein bands in polyacrylamide gels came in 1967, where the dye was dissolved in an acetic acid solution containing methanol.<ref>{{cite book | last1 = Altschul | first1 = A. M. | last2 = Evans | first2 = W. J. | chapter = Zone electrophoresis with polyacrylamide gel | title = Enzyme Structure | volume = 11 | year = 1967 | doi = 10.1016/S0076-6879(67)11019-7 | pages = 179–186 | series = Methods in Enzymology | isbn = 9780121818609 }}. Page 184 personal communication from W. J. Saphonov.</ref> It was subsequently discovered that the protein bands could be stained without staining the polyacrylamide by using a [[colloid]] of the G form of the dye in a [[trichloroacetic acid]] solution containing no methanol. With this procedure it was no longer necessary to destain the gel.<ref>{{ cite journal | last1 = Diezel | first1 = W. | last2 = Kopperschläger | first2 = G. | last3 = Hofmann | first3 = E. | year = 1972 | title = An improved procedure for protein staining in polyacrylamide gels with a new type of Coomassie Brilliant Blue | journal = Analytical Biochemistry | volume = 48 | pages = 617–620 | doi = 10.1016/0003-2697(72)90117-0 | pmid = 4115985 | issue = 2 }}</ref> Modern formulations typically use a colloid of the G form of dye in a solution containing phosphoric acid, [[ethanol]] (or methanol) and [[ammonium sulfate]] (or [[aluminium sulfate]]).<ref>{{ cite journal | last1 = Neuhoff | first1 = V. | last2 = Stamm | first2 = R. | last3 = Eibl | first3 = H. | year = 1985 | title = Clear background and highly sensitive protein staining with Coomassie Blue dyes in polyacrylamide gels: a systematic analysis | journal = Electrophoresis | volume = 6 | pages = 427–448 | doi = 10.1002/elps.1150060905 | issue = 9 | s2cid = 94797941 }}</ref><ref>{{ cite journal | last1 = Candiano | first1 = G. | last2 = Bruschi | first2 = M. | last3 = Musante | first3 = L. | last4 = Santucci | first4 = L. | last5 = Ghiggeri | first5 = G. M. | last6 = Carnemolla | first6 = B. | last7 = Orecchia | first7 = P. | last8 = Zardi | first8 = L. | last9 = Righetti | first9 = P. G. | year = 2004 | title = Blue silver: a very sensitive colloidal Coomassie G-250 staining for proteome analysis | journal = Electrophoresis | volume = 25 | issue = 9 | pages = 1327–1333 | doi = 10.1002/elps.200305844 | pmid = 15174055  | s2cid = 25960150 }}</ref><ref>{{ Cite book | last1 = Steinberg | first1 = T. H. | chapter = Chapter 31 Protein Gel Staining Methods | year = 2009 | title = Guide to Protein Purification, 2nd Edition | volume = 463 | pages = 541–563 | doi = 10.1016/S0076-6879(09)63031-7 | pmid = 19892191 | series = Methods in Enzymology | isbn = 9780123745361 }}</ref><ref>{{ cite journal | last1 = Pink | first1 = M. | last2 = Verma | first2 = N. | last3 = Rettenmeier | first3 = A. W. | last4 = Schmitz-Spanke | first4 = S. | title = CBB staining protocol with higher sensitivity and mass spectrometric compatibility | journal = Electrophoresis | year = 2010 | volume = 31 | pages = 593–598 | doi = 10.1002/elps.200900481 | pmid = 20162584 | issue = 4 | s2cid = 39038371 }}</ref>

The [[Bradford protein assay|Bradford assay]] uses the spectral properties of Coomassie brilliant blue G-250 to estimate the amount of protein in a solution.<ref>{{ cite journal | last = Bradford | first = M. M. | author-link = Marion M. Bradford | year = 1976 | title = Rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding | journal = Analytical Biochemistry | volume = 72 | issue = 1–2 | pages = 248–254 | doi = 10.1016/0003-2697(76)90527-3 | pmid = 942051 | s2cid = 4359292 }}</ref> A protein sample is added to a solution of the dye in phosphoric acid and ethanol. Under the acid conditions the dye is normally a brownish colour but on binding to the protein the blue form of the dye is produced. The optical absorbance of the solution is measured at a wavelength of 595&nbsp;nm. The dye is noted for its high level of sensitivity: 5 μg of protein{{Clarify|reason=in what volume?|date=January 2022}} can be detected. However, among the disadvantages of the method is its variability of color development with different proteins: the absorbance change per unit mass of proteins varies with the type of the protein.<ref>{{Cite journal|last1=Congdon|first1=Robert W.|last2=Muth|first2=Gregory W.|last3=Splittgerber|first3=Allan G.|date=September 1993|title=The binding interaction of Coomassie blue with proteins.|journal=Analytical Biochemistry|volume=213|issue=2|pages=407–413|doi=10.1006/abio.1993.1439|pmid=7694523}}</ref>

On binding to a protein, the negatively charged Coomassie brilliant blue G-250 dye molecule will give an overall negative charge to the protein. This property can be used to separate proteins or protein complexes using polyacrylamide gel electrophoresis under non-denaturing conditions in a technique called [[Native PAGE#Blue Native PAGE|blue native PAGE]].<ref>{{ cite journal | last1 = Schägger | first1 = H. | last2 = Jagow | first2 = G. | year = 1991 | title = Blue native electrophoresis for isolation of membrane protein complexes in enzymatically active form | journal = Analytical Biochemistry | volume = 199 | pages = 223–231 | doi = 10.1016/0003-2697(91)90094-A | issue = 2 | pmid = 1812789 }}</ref><ref>{{cite journal | last1 = Wittig | first1 = I. | last2 = Braun | first2 = H. P. | last3 = Schägger | first3 = H. | year = 2006 | title = Blue native PAGE | journal = Nature Protocols | volume = 1 | pages = 418–428 | doi = 10.1038/nprot.2006.62 | issue = 1 | pmid = 17406264 | s2cid = 19715017 }}</ref> The mobility of the complex in the polyacrylamide gel will depend on both the size of the protein complex (i.e., the molecular weight) and the amount of dye bound to the protein.

Coomassie blue staining can also be used as a [[Western blot normalization|loading control staining method]] in western blot analysis.<ref>{{cite journal | last1 = Welinder | first1 = Charlotte | last2 = Ekblad | first2 = Lars | year = 2011 | title = Coomassie Staining as Loading Control in Western Blot Analysis | journal = Journal of Proteome Research | volume = 10 | issue = 3| pages = 1416–1419 | doi = 10.1021/pr1011476 | pmid = 21186791 }}</ref> It is applied as an anionic pre-antibody stain.

== Medical uses ==
{{anchor|Medical uses}}
In 2009, brilliant blue G was used in scientific experiments to treat [[spinal cord injury|spinal injuries]] in laboratory rats.<ref name=peng>{{ cite journal | last1 = Peng | first1 = W. | last2 = Cotrina | first2 = M. L. | last3 = Han | first3 = X. | last4 = Yu | first4 = H. | last5 = Bekar | first5 = L. | last6 = Blum | first6 = L. | last7 = Takano | first7 = T. | last8 = Tian | first8 = G. F. | last9 = Goldman | first9 = S. A. | last10 = Nedergaard | first10 = M. | title = Systemic administration of an antagonist of the ATP-sensitive receptor P2X7 improves recovery after spinal cord injury | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | pages = 12489–12493 | year = 2009 | doi = 10.1073/pnas.0902531106 | pmid = 19666625 | pmc = 2718350 | issue = 30 | display-authors = 8 | doi-access = free }}</ref> It acts by reducing the body's natural swelling response, which can cause neurons in the area to die of metabolic stress. Testing on the rats proved effective. In comparison to the rats that had not received the dye, the rats that were treated with the dye performed better on motion tests.<ref>{{cite web|last1=Ehrenberg|first1=Rachel|title=Brilliant blue for the spine|url=https://www.sciencenews.org/article/brilliant-blue-spine|website=Science News|publisher=Society for Science & the Public|access-date=9 December 2017|language=en|date=23 September 2013}}</ref> It is unknown whether this treatment can be used effectively in humans. The animal experiments administered the dye within 15 minutes of injury, but to be effective in a real-life setting, where it may take time for a patient to reach the emergency room, the treatment needs to be effective even when administered up to two hours after injury. The only reported side effect was that the rats temporarily turned blue.<ref name=peng/><ref>{{ cite news | url = https://www.telegraph.co.uk/news/science/science-news/5921266/Blue-MandMs-mend-spinal-injuries.html | title = Blue M&Ms 'mend spinal injuries' | newspaper=Telegraph | date = 2009-07-28 | access-date = 2010-01-19 }}</ref><ref>{{ cite news | url = https://www.wired.com/wiredscience/2009/07/bluerats/ | title = Blue Food Dye Treats Spine Injury in Rats | newspaper = Wired.com | date = 2009-07-27 | access-date = 2010-01-19 }}</ref>

Under the trade names ILM Blue and Brilliant Peel, brilliant blue G is used as a stain to assist surgeons in retinal surgery.<ref>{{ Cite book | last1 = Mennel | first1 = S. | last2 = Meyer | first2 = C. H. | last3 = Schmidt | first3 = J. C. | last4 = Kaempf | first4 = S. | last5 = Thumann | first5 = G. | title = Trityl dyes patent blue V and brilliant blue G - clinical relevance and in vitro analysis of the function of the outer blood-retinal barrier | volume = 42 | pages = 101–114 | year = 2008 | doi = 10.1159/000138988 | pmid = 18535384 | series = Developments in Ophthalmology | isbn = 978-3-8055-8551-4 }}</ref> In December 2019, brilliant blue G (under the trade name TissueBlue, DORC International, Netherlands) was approved for use in humans in the United States.<ref>{{cite web | title=Drug Trials Snapshots: TissueBlue | website=U.S. [[Food and Drug Administration]] (FDA) | date=20 December 2019 | url=http://www.fda.gov/drugs/drug-approvals-and-databases/drug-trials-snapshots-tissueblue | archive-url=https://web.archive.org/web/20200923010709/https://www.fda.gov/drugs/drug-approvals-and-databases/drug-trials-snapshots-tissueblue | url-status=dead | archive-date=September 23, 2020 | access-date=17 March 2020}}</ref><ref>{{cite web | title=TissueBlue- brilliant blue g injection, solution | website=DailyMed | date=29 December 2019 | url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9d4b28b4-c582-4e2c-abd9-f7e203378e2d | access-date=17 March 2020}}</ref><ref>{{cite web | title=Drug Approval Package: TissueBlue | website=U.S. [[Food and Drug Administration]] (FDA) | date=10 January 2020 | url=https://www.accessdata.fda.gov/drugsatfda_docs/nda/2019/209569Orig1s000TOC.cfm | access-date=17 March 2020}}{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}}</ref>

Tissueblue was approved for medical use in Canada in January 2021.<ref>{{cite web | title=Summary Basis of Decision (SBD) for Tissueblue | website=Health Canada | date=23 October 2014 | url=https://hpr-rps.hres.ca/reg-content/summary-basis-decision-detailTwo.php?linkID=SBD00532&lang=en | access-date=29 May 2022}}</ref><ref>{{cite web | title=Health product highlights 2021: Annexes of products approved in 2021 | website=[[Health Canada]] | date=3 August 2022 | url=https://www.canada.ca/en/health-canada/services/publications/drugs-health-products/health-product-highlights-2021/appendices.html | access-date=25 March 2024}}</ref>

== Application in forensic science ==
The ability of the Coomassie dye to target [[amino acids]] with aromatic groups ([[phenylalanine]], [[tyrosine]], [[tryptophan]]) and basic side chains ([[lysine]], [[arginine]] and [[histidine]]) allows the [[Bradford assay]] to be used for fingerprint analysis.  The assay was successfully used to identify the [[biological sex]] of the fingerprint.  Female samples were shown to have a higher absorbance than male samples when tested at similar wavelengths.  This provides a simpler method for fingerprint analysis by reducing the number of amino acids needing to be analyzed from 23 to 6 and requires little to no assay preparation, in contrast to the [[ninhydrin]] chemical assay, which requires assay preparation such as heating and enzyme cascade.<ref>{{Cite journal|last1=Brunelle|first1=Erica|last2=Le|first2=Anh Minh|last3=Huynh|first3=Crystal|last4=Wingfield|first4=Kelly|last5=Halámková|first5=Lenka|last6=Agudelo|first6=Juliana|last7=Halámek|first7=Jan|date=2017-04-04|title=Coomassie Brilliant Blue G-250 Dye: An Application for Forensic Fingerprint Analysis|journal=Analytical Chemistry|volume=89|issue=7|pages=4314–4319|doi=10.1021/acs.analchem.7b00510|pmid=28293949|issn=0003-2700}}</ref>

== References ==
{{reflist}}

==Further reading==
*{{Cite book| last1=Gessner | first1=T. | last2=Mayer | first2=U. | year=2002 | contribution= Triarylmethane and Diarylmethane Dyes | title= Ullmann's Encyclopedia of Industrial Chemistry 6th Edition | publisher=Wiley-VCH | place=Weinheim | doi=10.1002/14356007.a27_179 | isbn=978-3527306732 }}

== External links ==
* {{cite web | title=Food dye 'may ease spinal injury' | website=[[BBC News Online]] | date=28 July 2009 | url=https://news.bbc.co.uk/2/hi/health/8170033.stm }}

{{Purinergics}}
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[[Category:Acid dyes]]
[[Category:Anilines]]
[[Category:Benzenesulfonates]]
[[Category:Benzenesulfonic acids]]
[[Category:Biochemistry detection reactions]]
[[Category:Phenol ethers]]
[[Category:Protein dyes]]
[[Category:Staining dyes]]
[[Category:Triarylmethane dyes]]