Editing High-performance liquid chromatography (section)

===Pump pressure===
[[Pump]]s vary in pressure capacity, but their performance is measured on their ability to yield a consistent and reproducible [[volumetric flow rate]]. [[Pressure]] may reach as high as 60&nbsp;MPa (6000&nbsp;[[Pound per square inch|lbf/in<sup>2</sup>]]), or about 600&nbsp;atmospheres. Modern HPLC systems have been improved to work at much higher pressures, and therefore are able to use much smaller particle sizes in the columns (<2&nbsp;μm). These "ultra high performance liquid chromatography" systems or UHPLCs, which could also be known as ultra high pressure chromatography systems,<ref>{{cite journal | doi=10.1016/j.chroma.2005.11.118 | title=Ultrahigh pressure liquid chromatography using elevated temperature | date=2006 | last1=Xiang | first1=Yanqiao | last2=Liu | first2=Yansheng | last3=Lee | first3=Milton L. | journal=Journal of Chromatography A | volume=1104 | issue=1–2 | pages=198–202 | pmid=16376355 }}</ref> can work at up to 120&nbsp;MPa (17,405&nbsp;lbf/in<sup>2</sup>), or about 1200&nbsp;atmospheres.<ref>[http://www.agilent.com/en-us/products/liquid-chromatography/lc-pumps-vacuum-degassers/1290-infinity-quaternary-pump#specifications  1290 Infinity Quaternary Pump] {{Webarchive|url=https://web.archive.org/web/20151120172747/http://www.agilent.com/en-us/products/liquid-chromatography/lc-pumps-vacuum-degassers/1290-infinity-quaternary-pump#specifications |date=2015-11-20 }}. Agilent</ref> The term "UPLC"<ref>{{cite web|url=http://www.waters.com/waters/en_US/Trademarks/nav.htm?cid=1000238&locale=en_US|title=Trademarks : Waters|last=waters|website=www.waters.com}}</ref> is a trademark of the [[Waters Corporation]], but is sometimes used to refer to the more general technique of UHPLC.