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Innovative instrument design and applications in supercritical fluid chromatography and extraction

Thesis/Dissertation ·
OSTI ID:7102356

A novel sample introduction system was developed for supercritical fluid chromatography. The solventless injector utilizes a gas purge for solvent elimination and is capable of handling large sample volumes. Successful operation depends on the difference in volatility between the solvent and the analyte along with effective refocusing mechanisms at the head of the column. Reduced analysis times are achieved by in-line derivatization to permit the separation of polar analytes and elimination of volatile reagents and by products. The construction of a SFC restrictor from a 2 mm metal disc was described. The design is compact, robust and will readily interface with existing detectors. Preliminary results indicate that variable flow control can be achieved by temperature programming. The Knox equation was useful in illustrating the limitations of the solventless injector during isochloric conditions and proved that small particle (<10[mu]m) columns packed by the supercritical fluid displacement method are identical to those packed by the high pressure slurry packing method developed for HPLC. Supercritical CO[sub 2] and microbore columns are compatible with GC style detectors (FID). The use of formamide as a modifier improves the chromatographic properties for compounds containing nitrogen atoms and is compatible with the FID. SFE/SFC with formic acid modified CO[sub 2], polymer encapsulated stationary phases and the FID represent a considerable advance in the analysis of organotin compounds. The method is capable of extracting and separating a diverse group of industrially important organotin compounds. Triorganotins were determined in marine paint, potatoes, almonds and cation exchange resin. Diorganotin compounds were determined in PVC and cation exchange resin. The solventless injector allowed on line collection from the SFE cell and direct introduction to the analytical column.

Research Organization:
Wayne State Univ., Detroit, MI (United States)
OSTI ID:
7102356
Country of Publication:
United States
Language:
English