Editing High-performance liquid chromatography (section)

==History and development==

Prior to HPLC, scientists used benchtop column liquid chromatographic techniques. Liquid chromatographic systems were largely inefficient due to the flow rate of [[solvents]] being dependent on gravity. Separations took many hours, and sometimes days to complete. [[Gas chromatography]] (GC) at the time was more powerful than [[liquid chromatography]] (LC), however, it was obvious that gas phase separation and analysis of very polar high molecular weight [[biopolymers]] was impossible.<ref name=Karger>{{cite journal|author=Karger, Barry L. |year=1997|title=HPLC: Early and Recent Perspectives|journal= Journal of Chemical Education |volume=74|issue=1|pages=45|doi=10.1021/ed074p45|bibcode=1997JChEd..74...45K}}</ref> GC was ineffective for many life science and health applications for biomolecules, because they are mostly non-[[Volatile organic compound|volatile]] and thermally unstable at the high temperatures of GC.<ref name=Henry>Henry, Richard A. (1 February 2009) [http://www.chromatographyonline.com/early-days-hplc-dupont "The Early Days of HPLC at Dupont"] {{Webarchive|url=https://web.archive.org/web/20200801185002/http://www.chromatographyonline.com/early-days-hplc-dupont |date=2020-08-01 }}. Chromatography Online. Avanstar Communications Inc.</ref> As a result, alternative methods were hypothesized which would soon result in the development of HPLC.{{citation needed|date=July 2024}}

Following on the seminal work of Martin and Synge in 1941, it was predicted by [[J. Calvin Giddings|Calvin Giddings]],<ref>{{Cite book |last=Giddings |first=Calvin |title=Dynamics of Chromatography: Principles and Theory |publisher=Marcel Dekker |year=1965 |isbn=}}</ref> Josef Huber, and others in the 1960s that LC could be operated in the high-efficiency mode by reducing the packing-particle diameter substantially below the typical LC (and GC) level of 150 μm and using pressure to increase the mobile phase velocity.<ref name=Karger /> These predictions underwent extensive experimentation and refinement throughout the 60s into the 70s until these very days.<ref name=":0">{{Cite book |last=Levin |first=Shulamit |title=Solid-Core or Fully Porous Columns in Ultra High-Performance Liquid Chromatography—Which Way to Go for Better Efficiency of the Separation? |publisher=CRC Press |year=2017 |isbn=9781315158075 |editor-last=Grinberg |editor-first=Nelu |edition=1 |series=Advances in Chromatography |volume=55 |location=Boca Raton |publication-date=2017 |pages=185–203 |chapter= |editor-last2=Carr |editor-first2=Peter W.}}</ref> Early developmental research began to improve LC particles, for example the historic Zipax, a superficially porous particle.<ref>Iler, R.K. (1979) ''The Chemistry of Silica''. John Wiley & Sons. New York.</ref>

The 1970s brought about many developments in hardware and instrumentation. Researchers began using pumps and injectors to make a rudimentary design of an HPLC system.<ref>{{cite journal|author1=Karger, B. L. |author2=Berry, L. V. |title=Rapid liquid-chromatographic separation of steroids on columns heavily loaded with stationary phase |journal=Clin. Chem. |volume=17 |issue=8 |pages=757–64 |pmid=4254537|year=1971 |doi=10.1093/clinchem/17.8.757 |doi-access=free }}</ref> Gas amplifier pumps were ideal because they operated at constant [[pressure]] and did not require leak-free seals or check valves for steady flow and good quantitation.<ref name=Henry/> Hardware milestones were made at Dupont IPD (Industrial Polymers Division) such as a low-dwell-volume gradient device being utilized as well as replacing the septum injector with a loop injection valve.<ref name=Henry/>

While instrumentation developments were important, the history of HPLC is primarily about the history and evolution of [[particle technology]].<ref name=Henry/><ref>{{Cite book |last=Neue |first=Uwe D. |title=HPLC columns: theory, technology, and practice |date=1997 |publisher=Wiley VCH |isbn=978-0-471-19037-0 |location=New York, NY}}</ref> After the introduction of porous layer particles, there has been a steady trend to reduced particle size to improve efficiency.<ref name=Henry/> However, by decreasing particle size, new problems arose. The practical disadvantages stem from the excessive pressure drop needed to force mobile fluid through the column and the difficulty of preparing a uniform packing of extremely fine materials.<ref>Giddings, J. Calvin (1965) ''Dynamics of Chromatography, Part I. Principles and Theory''. Marcel Dekker, Inc., New York. p. 281.</ref> Every time particle size is reduced significantly, another round of instrument development usually must occur to handle the pressure.<ref name=":0" /><ref name=Henry/>