Flow or Velocity? | 合法醫療器材資訊網

2016年2月29日—Ingaschromatography(GC),however,themobilephaseisverymuchcompressible,whichleadstopressure-,flow-,andvelocity-driveneffects ...

Chromatographers often use the terms carrier-gas flow and velocity interchangeably when discussing column parameters. In liquid chromatography, the two terms scale together, but in gas chromatography they do not: Doubling the flow does not double the velocity. This month’s “GC Connections” investigates the reasons for this non-intuitive behavior and how it affects best practices for gas chromatographers.

The subject of mobile-phase flow and linear velocity arises naturally in discussions of chromatography optimization. Many chromatographers may assume that doubling the flow or velocity also doubles the velocity or flow, respectively. In liquid chromatography (LC), this is certainly true if small side-effects are ignored, such as those caused by flow-driven heating. In gas chromatography (GC), however, the mobile phase is very much compressible, which leads...