GC FAQ's
What is Gas Chromatography?
Gas Chromatography is a separation science in which gas or volatile liquid mixtures are separated into individual chemical components which can be detected and quantified. Translated from Greek, chromatography literally means "color writing". One of the earliest experiments in modern separation sciences, performed by a Russian botanist named Mikhail Tswett, resulted in individual bands of color for each component separated - hence the name color writing. Today that name is largely a misnomer. Back to Top
How does Gas Chromatography work?
Individual chemical components separate at different rates as they transfer between a mobile gas phase (called a carrier gas) and a non-moving solid or liquid phase (called a stationary phase). The Stationary phases are contained in "columns". There are two types of separations that occur: Adsorption Gas Chromatography, in which molecules adsorb onto and desorb from a solid phase; and Partition Gas Chromatography, in which molecules diffuse into and out of a liquid phase based on the boiling point properties of the indiviual chemical components or the chemical affinity of the liquid phase for individual chemical components. Parameters which can affect separations include the type and flowrate of the carrier gas, the length and diameter of the column, the temperature of the system, and whether and how temperature programming is being used. Back to Top
Why should I use valves?
Gases and volatile liquids (those samples which are only liquid while under greater than ambient pressure or when chilled below ambient temperature) are compressible. It is generally desirable to inject exactly the same amount of sample each time. It is very difficult to inject exactly the same amount of a compressible sample using a gas-tight syringe. By using a valve, the same exact amount of sample may be injected every time, independant of the operator. Valves can also be used for column selection during an analysis, for detector selection during an analysis, for reversing flows through columns during the analysis, or for obtaining more separations from more columns in a single injection cycle. Using valves, when indicated, can increase efficiency, accuracy, repeatability, and reproducibility. Back to Top
When and Why should I work with RCS Group, LLC?
If you know what you need to analyze but don't know how to configure your gas chromatograph to perform the analysis, call and consult with us. Even if you know how to configure the system, but simply do not have the time or manpower to perform the configuration, let us know your design parameters or let us propose an alternative. In either case, we will provide you with a quotation which will describe the scope of work which we propose to perform and the design elements which we will use. We will delineate the components which will be identified and the advantages and limitations of the proposed configuration.
We also provide method development services to assist you in optimizing analyses which you may already have in your laboratory. Optimization may mean increasing separation resolution, decreasing analysis cycle times, helping you to obtain lower detection capability, changing integration parameters, or recalibrating. We want to help make your GC systems easier to operate and maintain.
Consulting and Training services are also offered. We can evaluate your exsting GC operations and make suggestions for improvements or assist you in planning new or remodeled facilities. Also, we offer training courses in a variety of venues and can offer specialized courses to meet specific training needs. Back to Top
|
|