Supercritical Fluid Chromatography (SFC) is a simple chromatographic technique that uses liquid carbon dioxide as the carrier fluid. Selerity’s Series 4000 Supercritical Fluid Chromatograph system is solvent-free and helium-free. Sample preparation and analysis is straightforward utilizing automatic valve injection of a small amount of undiluted sample. The optional Selerity SAS-100 liquid autosampler features a 50 sample position tray to serve high-throughput laboratory analysis needs, and the 0.75 mL autosampler vials minimize the sample amount requirement for each automated injection cycle.
Selerity Technologies is the market leader in Supercritical Fluid Chromatography systems in the petroleum industry. The Selerity Series 4000 is a “turn-key” Supercritical Fluid Chromatographic (SFC) instrument designed specifically for the petroleum industry to meet the needs of American Standard Testing and Materials (ASTM) methods such as ASTM D6550 and ASTM D5186 for final product testing of gasoline, aviation and diesel fuels.
The Selerity Series 4000 SFC is equipped with a syringe pump for a continuous stream of supercritical carbon dioxide as the carrier fluid, a flame ionization detector for the identification of hydrocarbon group types found in petroleum products, industry standard pneumatic rotary injection valves for repeatable sample introduction to the column, and rotary switching valves to direct the carrier flow to the appropriate columns per the method specifications. An optional positive pressure autosampler moves the sample automatically from vial to the injection valve. This “gas chromatograph” like supercritical fluid chromatograph makes meeting the rigorous performance requirements of ASTM D6550 and ASTM D5186 easy.
Supercritical Fluid Chromatography is a chromatographic technique in which the mobile phase, typically carbon dioxide, is taken to pressures and temperatures above its critical point. The supercritical fluid possesses densities and other properties that are intermediate between those of gases and liquids. Unique separation capabilities become possible for compounds that are not easily volatilized for gas chromatography (GC) and solubility properties occur for replacement of normal phase, high pressure liquid chromatography (HPLC) separations. Due to the “green” solvent properties, SFC is becoming the preferred separation method over HPLC. ASTM committee D02 has approved methods using supercritical fluid chromatography for group-type separations for testing gasoline, diesel and aviation products. These methods take advantage of the unique solubility to achieve a group type separation and the use of the most common universal detector in GC, the flame ionization detector.
ASTM D6550 is the Standard Test Method for the Determination of Olefin Content in Gasolines by Supercritical-Fluid Chromatography and ASTM D5186 is Standard Test Method for Determination of the Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels and Aviation Turbine Fuels by Supercritical Fluid Chromatography. Both D5186 the determination of aromatics and polynuclear aromatics in diesel and D6550 the determination of olefins in gasoline have been used as the regulatory method in the state of California since early 2000. The methods have been proven to be more accurate than the alternative ASTM D1319.
ASTM D1319 is the Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption. This method was accepted by ASTM in 1954 and has been the industry standard testing method for petroleum products. Recent events have led to problems with the method and both ASTM D5186 and D6550 are replacements to FIA. The Environmental Protection Agency (EPA) and California Air Resources Board (CARB) has both ASTM D6550 and ASTM D5186 as approved testing methods for final product release of gasoline and diesel fuels to measure and control the amount of the pollution causing compounds found in petroleum products.