Editing Einsteinium (section)

===Separation===
[[File:Elutionskurven Fm Es Cf Bk Cm Am.png|thumb|[[Elution]] curves: chromatographic separation of Fm(100), Es(99), Cf, Bk, Cm and Am]]
Separation procedure of einsteinium depends on the synthesis method. In the case of light-ion bombardment inside a cyclotron, the heavy ion target is attached to a thin foil, and the generated einsteinium is simply washed off the foil after the irradiation. However, the produced amounts in such experiments are relatively low.<ref name="h1583">[[#Haire|Haire]], p. 1583</ref> The yields are much higher for reactor irradiation, but there, the product is a mixture of various actinide isotopes, as well as lanthanides produced in the nuclear fission decays. In this case, isolation of einsteinium is a tedious procedure which involves several repeating steps of cation exchange, at elevated temperature and pressure, and chromatography. Separation from berkelium is important, because the most common einsteinium isotope produced in nuclear reactors, {{sup|253}}Es, decays with a half-life of only 20 days to {{sup|249}}Bk, which is fast on the timescale of most experiments. Such separation relies on the fact that berkelium easily oxidizes to the solid +4 state and precipitates, whereas other actinides, including einsteinium, remain in their +3 state in solutions.<ref name="h1584">[[#Haire|Haire]], pp. 1584–1585</ref>

Trivalent actinides can be separated from lanthanide fission products by a cation-exchange resin column using a 90% water/10% ethanol solution saturated with [[hydrochloric acid]] (HCl) as [[eluant]]. It is usually followed by [[anion-exchange chromatography]] using 6 [[molar concentration|molar]] HCl as eluant. A cation-exchange resin column (Dowex-50 exchange column) treated with ammonium salts is then used to separate fractions containing elements 99, 100 and 101. These elements can be then identified simply based on their elution position/time, using α-hydroxyisobutyrate solution (α-HIB), for example, as eluant.<ref name="book2">{{cite book|url=https://books.google.com/books?id=U4rnzH9QbT4C&pg=PA11|pages=9–11|title=The new chemistry|author=Hall, Nina|publisher=Cambridge University Press|date=2000|isbn=978-0-521-45224-3|access-date=2016-01-05|archive-date=2016-05-20|archive-url=https://web.archive.org/web/20160520024221/https://books.google.com/books?id=U4rnzH9QbT4C&pg=PA11|url-status=live}}</ref>

The 3+ actinides can also be separated via solvent extraction chromatography, using bis-(2-ethylhexyl) phosphoric acid (abbreviated as HDEHP) as the stationary organic phase, and nitric acid as the mobile aqueous phase. The actinide elution sequence is reversed from that of the cation-exchange resin column. The einsteinium separated by this method has the advantage to be free of organic complexing agent, as compared to the separation using a resin column.<ref name="book2" />