Christine Lynn Rankin

US Patent:

51415348, Aug 25, 1992

Filed:

Jun 18, 1991

Appl. No.:

7/717356

Inventors:

Richard D. Sacks - Ann Arbor MI
Mark A. Klemp - Ann Arbor MI
Christine L. Rankin - Ann Arbor MI

Assignee:

The Regents of the University of Michigan - Ann Arbor MI

International Classification:

B01D 1508

US Classification:

55197

Abstract:

A gas chromatography system of the type incorporating a thermal focusing chamber for introducing a sample into a column for separation and analysis. The system of the present invention provides benefits in terms of reducing memory effect of one analysis being influenced by prior experiments, a reduction in system dead volume which leads to broadening of peaks produced on the chromatogram and artifacts caused by sample decomposition. These advantages are achieved principally through a novel fluid circuit in which the sample is trapped onto the column by trapping it at the end of the thermal focusing chamber closest to the column. This feature has the effect of eliminating the necessity of the sample residing in the heated focusing chamber for a period giving rise to sample decomposition. This system further avoids the necessity of passing the inlet flow through mechanical valves which also contributes to memory effect. This system further has the benefit of enabling sampling of sources at various pressures including ambient pressure as an air quality sensing probe.

US Patent:

51415321, Aug 25, 1992

Filed:

Jun 5, 1991

Appl. No.:

7/710703

Inventors:

Richard D. Sacks - Ann Arbor MI
Christine L. Rankin - Ann Arbor MI

Assignee:

The Regents of the University of Michigan - Ann Arbor MI

International Classification:

B01D 1508

US Classification:

55 67

Abstract:

A gas chromatography system which incorporates a simplified sample injection system in which replaces conventional mechanical injection systems with one based strictly upon thermal trapping of a continuously supplied carrier gas and sample stream. The carrier gas and sample stream pass continuously through the device which incorporates a thermal focusing chamber which communicates with the inlet end of a gas chromatography separation column. By causing the focusing chamber temperature of a sample tube passing through the focusing chamber to be dropped, incoming components comprising the sample stream are condensed and trapped. Injection into the column occurs rapidly heating the sample in the thermal focusing chamber causing a narrow sample plug to be introduced into the column. Various embodiments of this invention are intended for operation for evaluating carrier gas and sample stream provided at a above atmospheric pressure, or which are drawn through the system by vacuum source at the outlet end of the column. In addition, vacuum backflushing features are also described.

US Patent:

50964712, Mar 17, 1992

Filed:

Sep 28, 1990

Appl. No.:

7/590174

Inventors:

Richard Sacks - Ann Arbor MI
Christine Rankin - Ann Arbor MI
Mark Klemp - Ann Arbor MI

Assignee:

The Regents of the University of Michigan - Ann Arbor MI

International Classification:

B01D 1508

US Classification:

55 67

Abstract:

Gas chromatography apparatus and procedures are described which enables gas chromatography to be carried out more rapidly than in accordance with prior art techniques and further enables chromatogram peaks caused by materials of interest from being obscured due to their super imposition upon high peak long durations produced by another component of peaks in an organic mixture. Reductions in chromatography evaluation time are achieved through employing a vacuum pump which caused backflushing of a very short column after materials of interest have been eluted but before higher boiling points components of the mixture have eluted. Backflushing is carried out using a vacuum pressure source which when used with a short column, permits rapid and complete backflushing. The chromatography system according to this invention allows simultaneous column backflushing while a new sample is being collected in a cooling chamber for cryofocussing for a subsequent injection. Another aspect of the invention is to cause a reversal in the flow direction through the column to occur at or just after a high intensity long duration peak causing component the mixture has eluted causing the remaining components to be drawn back into a thermal focusing chamber for subsequent injection.