Method and apparatus for sample analysis
View Patent ↗Methods and systems for analyzing samples, such as gas samples, are described. One method comprises providing a gas sample, increasing pressure applied to the gas sample to compress the sample to a smaller volume and provide a pneumatically focused gas sample, and analyzing the pneumatically focused gas sample using any of a variety of analytical techniques. Also disclosed are systems for gas analysis, including systems for analysis of pneumatically focused, and thereby concentrated, gas samples and for analysis of particulate matter in gas samples. Analytical systems constructed within personal computer cases also are disclosed.
1. A system for concentrating and analyzing a gaseous sample, the system comprising:
a separatory column;
a pressurizer for compressing a gaseous sample from a first volume to a second volume, the second volume being smaller than the first volume, the pressurizer being fluidly connected to and upstream of the separatory column;
a first sample passageway fluidly connected to and downstream of the separatory column;
a second sample passageway fluidly connected to and downstream of the separatory column and fluidly connected to the first sample passageway, the second sample passageway including a flow restrictor that inhibits gas from flowing through the second sample passageway;
a pressure-increasing valve arrangement fluidly connected to and downstream of the separatory column, which valve arrangement automatically
(a) blocks flow through the first sample passageway and forces flow through the second sample passageway while the apparatus operates to compress the sample, thereby reducing the flow rate through the system and increasing system pressure to pneumatically focus the gaseous sample, and
(b) permits flow through the first sample passageway once the sample has been compressed to the second volume and a portion of the sample has flowed through the flow restrictor, thereby allowing flow to resume through the first sample passageway and separation of analytes previously adsorbed at the head of the separatory column; and
one or more detectors located to receive analytes from at least the first sample passageway and to detect analytes delivered to the detector from the first sample passageway.
2. The system of claim 1 wherein the pressure-increasing valve arrangement includes a check valve that operates to block flow through the first sample passageway when pressure in the first sample passageway exceeds a predetermined amount.
3. The system of claim 1 wherein the flow restrictor is a solenoid driven needle valve, a calibrated leak, a frit restrictor, a tapered capillary restrictor, a feedback regulator, a manually operated needle valve, or a crimped capillary flow regulator.
4. The system of claim 1 wherein the one or more detectors are also located to receive analytes from the second sample passageway and to detect analytes delivered to the one or more detectors from the second sample passageway.
5. The system of claim 4 wherein the one or more detectors are located to receive the analytes from the second sample passageway after the analytes have passed through the flow restrictor.
6. The system of claim 1 further comprising one or more additional detectors located to receive analytes from the separatory column, the one or more additional detectors being located to receive the analytes from one or both of the first sample passageway and the second sample passageway.
7. The system of claim 1 wherein at least one of the one or more detectors is a flame ionization detector, a photoionization detector, a flame photometric detector, a UV/visible spectrometer, an infrared spectrometer, or a mass spectrometer.
8. The system of claim 1 wherein the second sample passageway is open to the atmosphere downstream of the flow restrictor so that gas passing through the flow restrictor is vented to the atmosphere.
9. The system of claim 1 wherein the system is contained in a computer case.
10. The system of claim 1 wherein the pressurizer is a mechanical pump or regulated supply of a carrier gas at an elevated pressure.
11. The system of claim 1 further comprising a valve arrangement which directs flow from the pressurizer to the separatory column.