Chromatograph Sample Valves
Arguably, the component most critical to measurement accuracy in a gas chromatograph is the sample valve. Its purpose is to inject the exact same sample quantity into the column at…
Industrial Applications of Chromatographs
Since process chromatographs have the ability to independently analyze the quantities of multiple species within a chemical sample, these instruments are inherently multi-variable. A single analog output signal (e.g. 4-20…
Measuring Gases Concentration in Chromatograph
While time is the variable used by a chromatograph to discriminate between different species (types) of chemical compounds, the concentration (quantity) of each chemical compound in the sample is inferred…
Thermal Conductivity Detector (TCD) Principle
Thermal conductivity detectors work on the principle of heat transfer by convection (gas cooling). Here, the assumption is that sample compounds will have different thermal properties than the carrier gas.…
Flame Ionization Detector (FID) Principle
Several different detector designs exist for process gas chromatographs. The two most common are the flame ionization detector (FID) and the thermal conductivity detector (TCD). Other detector types include the…
Online Gas Chromatograph Principle
The most common type of chromatography used in continuous process analysis is the gas chromatograph (abbreviated “GC”), so named because the mobile phase is a gas (or a vapor (…
Thin-Layer Chromatography : Manual Method
One of the manual chromatography methods taught to beginning chemists is thin-layer chromatography, also known as TLC. An illustrated sequence showing thin-layer chromatography appears here: As solvent wicks up the…
What is Chromatography ?
Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun is fired, all the runners begin running the race, starting from…
pH measurement
Potentiometric pH measurement Color-change is a common pH test method used for manual laboratory analyses, but it is not well suited to continuous process measurement. By far the most common…
Electrodeless Conductivity Probes Principle
An entirely different design of conductivity cell called electrodeless uses electromagnetic induction rather than direct electrical contact to detect the conductivity of the liquid solution. This cell design enjoys the…
