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SYSTEM AND METHOD FOR INJECTING LIQUEFIED GAS SAMPLE INTO A GAS CHROMATOGRAPH

IP.com Disclosure Number: IPCOM000174222D
Publication Date: 2008-Sep-02

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention relates, in general, to the field of gas chromatography. More specifically, the present invention relates to a system and method for injecting liquefied gas (LG) samples into a gas chromatograph.

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SYSTEm and method FOR injecting liquefied gas sample into a Gas chromatograph

 The present invention relates, in general, to the field of gas chromatography. More specifically, the present invention relates to a system and method for injecting liquefied gas (LG) samples into a gas chromatograph.

Typically, a gas chromatography system, used for LG sample analysis, includes an LG sample cylinder, a liquefied sample valve (LSV) and a gas chromatograph. The LG sample cylinder stores an LG sample that is required to be analyzed by the gas chromatograph. Typically, the LG sample exists as a mixture of a vapor form and a liquid form. However, the LG sample cylinder may include a piston that compresses the stored LG sample to a predefined storage pressure value, such that the LG sample exists only in the liquid form. The gas chromatograph includes components required for performing a chromatography method, such as an inlet, a column, an oven and a detector. The LSV includes a sample loop, wherein the sample loop is a tube of a predefined volume in which the LG sample is introduced before the LG sample is injected into the inlet. The LSV operates to fill the sample loop with the LG sample and thereafter, allows a flow of carrier gas to sweep the LG sample from the sample loop into the inlet. Thereafter, the LG sample is vaporized and introduced into the column.

The disclosed invention, proposes to employ a pressurized sample injection (PSI) system for injecting precise volumetric quantities of the LG sample into the inlet. The operation of the PSI system compresses the LG sample, present in an injection assembly of the PSI system, to a predefined pressure value before injecting the LG sample into the inlet. The compression of the LG sample ensures that the entire LG sample, present in the injection assembly, is converted into the liquid form and is maintained at a constant pressure and temperature. Thus, the LG sample to be analyzed is maintained at a uniform density when the LG sample is injected into the inlet.     

The disclosed invention provides a system and method for injecting the LG sample into the gas chromatograph. The invention ensures that equal volumes of the LG sample to be analyzed are injected into the inlet during each injection. Thereby, the disclosed invention helps in achieving a precise and accurate chromatography analysis of the LG sample and helps in reducing errors that occur due to inaccuracies in the volume of the LG sample injected for analysis.

Figs. 1A, 1B, 1C, 1D, 1E and 1F are block diagrams representing a PSI system 100 for injecting an LG sample into an inlet 122 of a gas chromatograph, in accordance with various embodiments of the present invention.

PSI system 100 includes a 3-way valve 102, a pressure chamber 104, an LSV 106, a vent chamber 108, a 2-way valve 110, a high pressur...