What is Gas Chromatography?
Chromatography is the science of separating a mix of compounds into homogeneous groups; Gas Chromatography is the separation of a blend of compounds in the gas phase.
How Are Compounds Separated?
Compounds can be separated in a variety of ways. In Gas Chromatography analysis, a GC system consists of an inlet, a capillary tube, and a detection device, all mounted to an oven.
When a sample is injected into the inlet, it is picked up by a gas flow and passed into the capillary column. The oven then heats the column, separating the compounds by boiling point. Generally speaking, lighter and smaller compounds have a lower boiling point and migrate through the column faster than heavier or larger compounds. At the exit of the column, you find the detector that works to identify the compounds as they exit the column.
What Does a GC Detector Do?
GC detectors work in various ways. Most of the time, detectors will destroy the compounds as they pass through, and a particular reaction will give a response or peak in the detector. The GC operator can better understand the compound's identity based on the time it takes for the migration and the detector's response.
GC Detectors are designed with varying levels of sensitivity and detection, and the method by which they destroy the sample to produce a response.
The PFPD is a pulsed flame photometric detector. This means a flame is ignited as the sample and carrier gas exit the column. The photometric detector analyzes the light produced from the combustion and determines the constituents of the compounds. The PFPD is great for sulfur.
The ELCD, or electrolytic conductivity detector, uses a recycling stream of solvent to pick up a carrier gas and sample passed through a heated (900-1000*C) reactor. The resulting gas/solvent mixture is passed through a conductivity cell that changes electric potential (peak).
The XSD is similar to the ELCD but uses no solvent stream but instead uses a probe inserted at the end of the catalytic reaction tube. As the compounds hit the probe, a thermos ionic response is detected to generate the peak.
The PID is a non-destructive detector that uses a UV lamp to excite photo-active compounds to a higher electric state. A sensor then detects these compounds within the PID body where the peak is generated. Since the PID is non-destructive, it can be used with the above detectors (except for PFPD), where the compounds can be passed through the detector and then into a destructive detector.
The Impact of GC Systems & Detectors
GC systems are utilized for many types of analysis where organic compounds are the focus. Laboratories are trying to determine the number of organic compounds in a given sample or what specific organic compounds a sample contains.
GC Systems and detectors are great for laboratories that analyze organic compounds when other analytical chemistry methods, such as wet chemistry, are not feasible or appropriate. Environmental and Food & Beverage labs and oil & gas or petrochemical laboratories always search for the lowest detection level.
Gas Chromatography Equipment at OI Analytical
Xylem Lab Solutions unifies a variety of instruments to serve a single purpose: provide technical solutions for laboratories across the globe. Our Gas Chromatography (GC) portfolio is designed to improve the way resources are used and conserved in the lab, regardless of application. Our detectors are great for specific applications where target compounds are mostly known to be absent, and the analysis confirms that.
Our innovative product portfolios provide sustainable solutions for our customers and our communities.
Selective GC Detectors
Our selective GC detectors provide solutions to challenging analytical applications. Detecting sulfur and halogenated species in petrochemicals, trace levels of organochlorine and organophosphorus pesticides in food or environmental samples, and sulfur and aromatic compounds in flavor and fragrance extracts are prime examples of applications that benefit from the use of selective GC detectors. Compatible detectors are available for current models of GC instruments manufactured by Agilent, Shimadzu, Thermo, and PerkinElmer.
Gas Chromatography Systems
Our high-performance, fully integrated GC systems are optimal for analyzing several compound classes in various matrices with excellent selectivity and sensitivity. For example, our BTEX system with Purge and Trap (P&T) extracts compounds from a representative sample, chromatographically separates, and selectively detects target compounds following specific regulatory methods to measure aromatic, aliphatic, and halogenated hydrocarbons in environmental samples. Our pesticide system may utilize either the ELCD or XSD for selective analysis of pesticides and PCBs. The SPRO system is designed to analyze sulfur compounds in gas phase samples. The fluorinated by-product system (FBA) uses the ELCD to measure total fluorinated contaminants in petrochemical streams.
Sample Processors & Sample Introduction
Maximize your laboratory's efficiency and investment with our state-of-the-art P&T concentrators and autosamplers. Chemists around the world rely on our equipment for accurate and dependable results. Our slim-line, open-architecture P&T design saves benchtop space, simplifies troubleshooting, and minimizes downtime. Our sample introduction systems contribute to laboratory efficiency and productivity with proven technology, intuitive software, and trusted engineering.