Editing Prussian blue (section)

==Use==
===Pigment===
[[File:The Great Clock following restoration - May 2022 (52120750076).png|thumb|right|200px|The clock faces of the [[Big Ben|Great Clock of Westminster]], restored to their original 1859 color scheme of Prussian blue and gold<ref>{{cite web|url=https://www.parliament.uk/about/living-heritage/building/palace/big-ben/elizabeth-tower-and-big-ben-conservation-works-2017-/turning-big-bens-clock-dials-blue/| title=Turning Big Ben's clock dials blue| publisher=UK Parliament| access-date=21 October 2023}}</ref>]]
Because it is easily made, cheap, nontoxic, and intensely colored, Prussian blue has attracted many applications. It was adopted as a pigment very soon after its invention and was almost immediately widely used in oil paints, watercolor, and dyeing.<ref>Berrie, Barbara H. (1997). "Prussian Blue". In ''Artists' Pigments. A Handbook of their History and Characteristics'', E. W. FitzHugh (ed.). Washington, DC: National Gallery of Art. {{ISBN|0894682563}}.</ref> The dominant uses are for pigments: about 12,000 [[tonne]]s of Prussian blue are produced annually for use in black and bluish [[ink]]s. A variety of other pigments also contain the material.<ref name=Ullmann>Völz, Hans G. ''et al.'' (2006) "Pigments, Inorganic" in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a20_243.pub2}}.</ref> [[Engineer's blue]] and the pigment formed on [[cyanotype]]s—giving them their common name [[blueprint]]s. Certain [[crayon]]s were once colored with Prussian blue (later relabeled [[Midnight blue#Dark midnight blue (Crayola)|midnight blue]]). Similarly, Prussian blue is the basis for [[laundry bluing]].

Nanoparticles of Prussian blue are used as pigments in some cosmetics ingredients, according to the  European Union Observatory for Nanomaterials.

{{infobox color
|title=Prussian blue
|hex=003153
|source=[[swiss.csail.mit.edu]]<ref>[https://web.archive.org/web/20070226152114/http://swiss.csail.mit.edu/~jaffer/Color/resene.pdf]</ref>
|cmyk=1
}}

===Medicine===
{{Main|Prussian blue (medical use)}}
Prussian blue's ability to incorporate [[Valence (chemistry)|monovalent]] metallic [[cation]]s ({{chem2|Me(+)}}) makes it useful as a [[Chelation|sequestering agent]] for certain [[toxic heavy metal]]s. Pharmaceutical-grade Prussian blue in particular is used for people who have ingested [[thallium]] ({{chem2|Tl(+)}}) or [[radioactive decay|radioactive]] [[caesium]] ({{chem2|^{134}Cs(+), ^{137}Cs(+)}}). According to the [[International Atomic Energy Agency]] (IAEA), an adult male can eat at least 10&nbsp;g of Prussian blue per day without serious harm. The [[U.S. Food and Drug Administration]] (FDA) has determined the "500-mg Prussian blue capsules, when manufactured under the conditions of an approved New Drug Application, can be found safe and effective therapy" in certain poisoning cases.<ref>{{cite web| url =https://www.fda.gov/Drugs/EmergencyPreparedness/BioterrorismandDrugPreparedness/ucm130337.htm| title= Questions and Answers on Prussian Blue| website= [[Food and Drug Administration]]| archive-url= https://web.archive.org/web/20090710041011/https://www.fda.gov/Drugs/EmergencyPreparedness/BioterrorismandDrugPreparedness/ucm130337.htm| access-date= 2020-03-20| archive-date= 2009-07-10}}</ref><ref>{{cite web |title=Questions and Answers on Calcium-DTPA and Zinc-DTPA (Updated) |url=https://www.fda.gov/drugs/bioterrorism-and-drug-preparedness/questions-and-answers-calcium-dtpa-and-zinc-dtpa-updated |website=U.S. Food & Drug Administration |date=3 November 2018 |access-date=21 March 2020}}</ref> Radiogardase (Prussian blue insoluble capsules<ref>Radiogardase: [http://www.heyltex.com/radiogardasePackageInsert.php ''Package insert with formula''] {{webarchive|url=https://web.archive.org/web/20110320030420/http://www.heyltex.com/radiogardasePackageInsert.php |date=2011-03-20 }}</ref>) is a commercial product for the removal of [[caesium-137]] from the [[intestine]], so indirectly from the [[Circulatory system|bloodstream]] by intervening in the [[enterohepatic circulation]] of caesium-137,<ref>[http://www.heyltex.com/toxicology.php Heyltex Corporation – Toxicology] {{webarchive|url=https://web.archive.org/web/20071112025717/http://www.heyltex.com/toxicology.php |date=2007-11-12 }}</ref> reducing the internal residency time (and exposure) by about two-thirds. In particular, it was used to [[Sorption|adsorb]] and remove {{chem2|^{137}Cs(+)}} from those poisoned in the [[Goiânia accident]] in Brazil.<ref name=Dunbar/>

===Stain for iron===
Prussian blue is a common [[histopathology]] stain used by [[pathologist]]s to detect the presence of iron in [[biopsy]] specimens, such as in [[bone marrow]] samples. The original stain formula, known historically (1867) as "[[Perls Prussian blue]]" after its inventor, German pathologist [[Max Perls]] (1843–1881), used separate solutions of [[potassium ferrocyanide]] and acid to stain [[Tissue (biology)|tissue]] (these are now used combined, just before staining). Iron deposits in tissue then form the purple Prussian blue dye in place, and are visualized as blue or purple deposits.<ref>[https://www.scribd.com/doc/4448747/Perl Formula for Perls Prussian blue stain]. Accessed April 2, 2009.</ref>
<gallery mode="packed" heights="150">
File:Kupffer cell with hemosiderin and hepatocyte with lipofuscin.jpg|[[Histopathology]] of the liver, showing a [[Kupffer cell]]s with significant [[hemosiderin]] deposition next to a hepatocyte with [[lipofuscin]] pigment. H&E stain.
File:Kupffer cell with hemosiderin and hepatocyte with lipofuscin, iron stain.jpg|Prussian blue staining, highlighting the hemosiderin pigment as blue.
File:Intra-alveolar hemosiderin deposition - Prussian blue stain.jpg|Prussian blue stain
</gallery>

===By machinists and toolmakers===
[[Engineer's blue]], Prussian blue in an oily base, is the traditional material used for spotting metal surfaces such as [[surface plate]]s and [[journal bearing|bearing]]s for [[hand scraper|hand scraping]]. A thin layer of nondrying paste is applied to a reference surface and transfers to the high spots of the workpiece. The toolmaker then scrapes, stones, or otherwise removes the marked high spots. Prussian blue is preferable because it will not abrade the extremely precise reference surfaces as many ground pigments may. Other uses include marking gear teeth during assembly to determine their interface characteristics.

=== In analytical chemistry ===
Prussian blue is formed in the Prussian blue assay for total [[phenol]]s. Samples and phenolic standards are given acidic ferric chloride and ferricyanide, which is reduced to ferrocyanide by the phenols. The ferric chloride and ferrocyanide react to form Prussian blue. Comparing the absorbance at 700&nbsp;nm of the samples to the standards allows for the determination of total phenols or [[polyphenol]]s.<ref name="Hagerman2011">{{cite web |last=Hagerman |first=Ann E. |date=18 March 2011 |title=Tannin Chemistry |url= http://www.users.muohio.edu/hagermae/tannin.pdf |access-date=2009-12-19 |archive-url=https://web.archive.org/web/20130826003253/http://www.users.muohio.edu/hagermae/tannin.pdf |archive-date=2013-08-26 |url-status=dead }}&nbsp;(1.41&nbsp;MB)</ref><ref name="Graham1992">{{cite journal | last=Graham | first=Horace D. | date=1992 | title=Stabilization of the Prussian blue color in the determination of polyphenols | journal=Journal of Agricultural and Food Chemistry | volume=40 | issue=5 | pages=801–805 | issn=0021-8561 | doi=10.1021/jf00017a018}}</ref>

=== Household use ===
Prussian blue is present in some preparations of [[laundry bluing]], such as [[Mrs. Stewart's Bluing]].<ref name="Schwarcz Gazette 20164">{{cite web|url=https://montrealgazette.com/opinion/columnists/the-right-chemistry-columbo-your-laundry-and-liquid-bluing|title=The Right Chemistry: Columbo, your laundry and liquid bluing|author=Schwarcz, Joe|date=January 22, 2016|website=[[Montreal Gazette]]|access-date=February 28, 2017}}</ref>