Process gas chromatography is a technique utilized for the separation and examination of chemical compounds present in the gaseous state during industrial operations. Gas chromatograph devices heat and disperse samples across a stationary and a mobile phase, with an inert gas propelling molecules through a temperature-controlled column.
MERTELLS provides solutions based on gas chromatographs delivering dependable and accurate process analyses, featuring touch screen functionality for straightforward results. The chromatograph configurations, visual displays, and data are distinctly organized for ease of comprehension and upkeep. Since 1976, MERTELLS has been providing GC solutions to the oil & gas, refining, and petrochemical sectors globally.
Description
Gas chromatography is an analytical technique that separates and identifies the individual constituents within gaseous or volatile liquid mixtures. This method involves a mobile gas phase and a stationary phase, which is either an adsorbent material or a nonvolatile liquid. Each component of the mixture interacts differently with the stationary phase, leading to their separation.
The utility of gas chromatography stems from its ability to:
- Analyze gas samples and volatile liquids with boiling points up to approximately 300°C.
- Offer a straightforward and maintainable instrument setup.
A Gas Chromatograph (GC) is the instrument used for gas chromatography. It operates within a temperature-regulated chamber where a sample is introduced into a column by a carrier gas. As the sample progresses through the column, its components are separated and subsequently detected as electrical signals, forming a chromatogram. The concentration of each component is deduced from the chromatogram’s peak area.
For accurate measurements, the carrier gas should be stable and minimally affect the detector’s background signal. Common choices include inorganic gases like H2, He, and N2.
The separation process within the column involves the sample’s components moving with the carrier gas, dissolving into and emerging from the stationary phase at a rate determined by a specific partition coefficient for each component. This coefficient is the ratio of a component’s concentration in the stationary phase to that in the mobile phase when in equilibrium. The separation process results in the isolation of individual components over time.
Gas chromatography is an analytical method that involves the classification and separation of components within a gas or volatile liquid.
Types of Gas Chromatography Based on Separation Mechanism:
- Adsorption Chromatography: This method separates components based on their varying levels of adsorption to the stationary phase. Common stationary phases include materials like activated carbon, synthetic zeolite, and silica gel. It’s typically used for separating inorganic gases such as hydrogen (H2), nitrogen (N2), and carbon dioxide (CO2), as well as low-boiling-point hydrocarbons like methane (CH4), ethane (C2), and propane (C3).
- Partition Chromatography: This technique differentiates components based on their solubility in the stationary phase. High-boiling-point liquids, both non-polar and polar, are used as the stationary phase, which is coated on porous materials or the inner walls of the column. It’s mainly applied to separate organic substances with four or more carbon atoms, including hydrocarbons, alcohols, and organic acids.
Classification Based on Column Type:
- Open Tubular Column: An open tubular column is a hollow column with an inner coating of either powder or liquid stationary phase. These columns have an inner diameter ranging from 0.25 to 0.53 mm and are made from materials like fused silica or stainless steel with an inert coating. They can be tens of meters long and offer superior separation performance compared to packed columns.
- Packed Column: A packed column is filled with a powdered stationary phase. In process gas chromatography, these columns are often made of stainless steel with an inner diameter of 1 to 2 mm and are several meters long. The variety of packing materials available provides numerous options for tailoring separation characteristics.
