Optimization of internal valve injection in open tubular column supercritical fluid chromatography

✍ Scribed by Jari P. Tuominen; Karin E. Markides; Milton L. Lee

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 738 KB
• Volume: 3
• Category: Article
• ISSN: 1040-7685
• DOI: 10.1002/mcs.1220030309

✦ Synopsis

As in the case of all chromatographic methods, the ideal sample introduction method for supercritical fluid chromatography (SFC) would provide a narrow and sharp solvent peak (or no solvent peak), quantitative transfer of the sample into the column, and high reproducibility. Elimination of the solvent before the solutes enter the column would be preferred; however, this practice is always associated with the risk of partial solute elimination. In open tubular column SFC, samples are normally introduced using a smallvolume internal loop valve. These valves can be operated such that none, some, or all of the solvent is eliminated. Several approaches were quantitatively evaluated, and optimized conditions were determined. Particular attention was given to trace analysis. The minimum detectable levels (S/N >4) achievable using a flame ionization detector were determined to be approximately 30 ng (150 ppm) for split injection, 4 ng (20 ppm) for delayed split injection, and 1 ng (5 ppm) for direct injection.