AN SPE COLUMN/TEFLON SLEEVE ASSEMBLY FOR THE IN-LINE RETENTION DURING SUPERCRITICAL FLUID EXTRACTION OF TRACE LEVEL ANALITIES FROM BIOLOGICAL MATRICES

Authors: Maxwell, Robert; STOLKER A A M - NIPH, NETHERLANDS; Lightfield, Alan

Submitted to: Journal of High Resolution Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/1994
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Food Safety Inspection Service (FSIS), which monitors meat and meat products for the presence of veterinary pharmaceuticals, requires new methods in its surveillance program. Methods are needed that improve speed of sample analyses and reduce the use of organic solvents to comply with EPA mandates. A new technique, supercritical fluid extraction (SFE) is under investigation as a potential replacement for some regulatory methods. SFE employs carbon dioxide, a relatively innocuous gas in place of harmful organic solvents. Extracted compounds typically are collected after the carbon dioxide is dissipated as a gas (off-line). An alternative collection technique was developed whereby compounds are collected in the supercritical fluid (in-line). This innovation produces an extract containing less unwanted coextracted materials than that from the off-line technique and minimizes the need for additional sample clean-up. The new collection was tested with three anabolic steroids in chicken liver. Recoveries were in the 90% range for these compounds and were in good agreement with established methods. The new collector standardizes SFE recovery techniques and advances this technology to the stage where it can be used as a routine analytical tool in laboratories of regulatory agencies.

Technical Abstract: A collector assembly has been designed for use in commercial SFE vessels containing the sample matrix. This in-line assembly allows solutes extracted by supercritical fluids (SF) to be retained in-line on standard solid phase extraction (SPE) columns. The assembly consists of standard 1 mL or 3 mL SPE columns fitted into specially fabricated teflon sleeves. This SPE column/teflon sleeve assembly is inserted easily into the SFE vessel forming a leak-tight seal with the vessel's end cap at pressures up to 680 bar. Any sorbent type may be used in the in-line SPE column. After SFE, the SPE column is removed and the solutes recovered in one mL of the eluting solvent. No further cleanup is required prior to chromatographic analysis. A comparison was made of the solutes recovered by in-line and off-line techniques (after SF decompression) for the SFE of three anabolic steroids fortified in liver. The HPLC chromatograms of the steroids in the eluate from the off-line SPE columns were too complex for quantitation while in contrast the chromatograms for the steroids from the in-line columns were free of UV absorbing interferences and easily quantified.