US 5,135,549 AGranted

Chromatographic technique and apparatus

AssigneeBoard of Trustees of Southern Illinois University

InventorsJohn B. Phillips, Zaiyou Liu

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Abstract

To provide a compact, sensitive comprehensive, two-dimensional gas chromatograph, a chromatographic column has first and second sections in series with each other to permit the flow of sample and a carrier through the first section and the second section. The retention time of the second section is less than the band resolution time of the first section. To control the wave fronts between the first and second sections, first and second heaters are positioned to heat and drive off sample collected at the outlet of the first section for collection in the second section and to heat sample collected at the inlet of the second section so that the first heater rapidly drives off sample for collection in the second section and then the second section rapidly drives off sample in a sharp wave front while the first section is accumulating another band for later movement into the second section.

Claims88

Dependent claims

A method of two-stage thermal modulation for generating concentration pulses in a gas stream flowing through a tube, said tube comprising an inlet, an outlet, a first portion which is a length of said tube comprising a first stage, and a second portion which is a length of said tube comprising a second stage, said method comprising the steps of:

(a) creating a flow of carrier gas in a direction through said tube to produce a carrier gas flow;
(b) introducing a sample into the carrier gas flow, said sample comprising one or more sample substances;
(c) cooling the first stage;
(d) cooling the second stage;
(e) accumulating within the first stage for a period of time sample substances carried thereinto by the carrier gas, thus forming a first concentration;
(f) heating the first stage to release the first concentration into the carrier gas flow in the form of a first concentration pulse;
(g) carrying the first concentration pulse in said direction of carrier gas flow toward said second stage;
(h) accumulating said first concentration pulse at the inlet of said second stage so as to focus and hold therein for a period of time, sample substances of said first concentration pulse carried by the carrier gas, thus forming a second concentration;
(i) cooling the first stage so as to resume accumulating therein for a period of time sample substances carried thereinto by the carrier gas;
(j) heating the second stage so as to release said second concentration into the carrier gas flow in the form of a second concentration pulse, said second concentration pulse being more compact in distance and of shorter duration than said first concentration pulse;
and
(k) cooling the second stage.

9 more elements

A method of two-dimensional chromatography comprising the steps of:

(a) injecting a sample composed of one or more sample substances into a first dimension of chromatographic separation;
(b) carrying said sample along said first dimension of chromatographic separation in a direction so as to cause a first resolution of said sample into a series of bands;
(c) carrying said sample into a two-stage thermal modulator comprising a first stage and a second stage;
(d) cooling said first stage;
(e) cooling said second stage;
(f) accumulating a portion of the sample between said first dimension of chromatographic separation and a second dimension of chromatographic separation disposed in serial relationship with said first dimension of chromatographic separation, said accumulating comprising generating concentration pulses within said two-stage thermal modulator, wherein said generating concentration pulses comprises
(I) accumulating within the first stage for a period of time sample substances carried thereinto from the first dimension, thus forming a first concentration,
(II) heating the first stage to release the first concentration in said direction in the form of a first concentration pulse,
(III) carrying the first concentration pulse in said direction toward said second stage,
(IV) accumulating said first concentration pulse at an inlet of said second stage so as to focus and hold in the second stage, for a period of time, sample substances of said first concentration pulse thus forming a second concentration,
(V) cooling the first stage so as to resume accumulating therein for a period of time sample substances carried thereinto by the carrier gas;
(g) transmitting the accumulated portion of sample as a sharp wave front to an inlet of the second dimension of chromatographic separation by heating the second stage so as to release said second concentration into the carrier gas flow in the form of a second concentration pulse, said second concentration pulse being more compact in distance and of shorter duration than said first concentration pulse;
(h) cooling the second stage;
and
(i) carrying the portion of sample along the second dimension of chromatographic separation so as to cause a further resolution of said portion of sample;
repeating steps (f)-(i), so as to generate a multiplicity of said sharp wave fronts and a multiplicity of said further resolutions without materially changing said first resolution;
and
detecting said multiplicity of further resolutions with a first detector so as to generate a multiplicity of second dimension chromatograms together comprising a two-dimensional chromatogram of said sample.

15 more elements

A method of two-dimensional chromatographic separation comprising the steps of:

(a) injecting a sample composed of various sample substances into a first dimension of chromatographic separation;
(b) carrying said sample along said first dimension of chromatographic separation so as to cause a first resolution of said sample into a series of bands;
(c) accumulating a portion of the sample between said first dimension of chromatographic separation and a second dimension of chromatographic separation disposed in serial relationship with said first dimension of chromatographic separation;
(d) transmitting the accumulated portion of sample as a sharp wave front to an inlet of the second dimension of chromatographic separation;
(e) carrying the portion of sample along the second dimension of chromatographic separation so as to cause a further resolution of said portion of sample;
and
repeating steps (c), (d), and (e) so as to generate a multiplicity of said sharp wave fronts and a multiplicity of said further resolutions by said second dimension of chromatographic separation, without materially changing said first resolution;
detecting said multiplicity of further resolutions so as to generate a multiplicity of second dimension chromatograms together comprising a two-dimensional chromatogram of said sample;
and
tuning the orthogonality of said two-dimensional chromatographic separation by a method wherein said first dimension of chromatographic separation and said second dimension of chromatographic separation are serially disposed, said tuning comprising adjusting a retention time in said second dimension of chromatographic separation as a function of progress of said first dimension of chromatographic separation such that a statistical measure of peak scatter in a retention plane is substantially maximized, and the peak capacity of the chromatographic system approximates the arithmetic product of individual peak capacities of said first and said second dimension of chromatographic separation.

7 more elements

An apparatus for generating a concentration pulse of a sample, said apparatus comprising:

a tube having an inlet, an outlet, a first portion which is a length of said tube comprising a first stage, and a second portion which is a length of said tube comprising a second stage;
means for creating a flow of carrier gas in a direction through said tube to produce a carrier gas flow;
means for introducing a sample into the carrier gas flow, said sample comprising one or more sample substances;
means for cooling the first stage;
means for cooling the second stage;
means accumulating within the first stage for a period of time sample substances carried thereinto by the carrier gas, thus forming a first concentration;
means for heating the first stage to release the first concentration into the carrier gas flow in the form of a first concentration pulse;
means for carrying the first concentration pulse in said direction of carrier gas flow toward said second stage;
means for accumulating said first concentration pulse at the inlet of said second stage so as to focus and hold therein for a period of time, sample substances of said first concentration pulse carried by the carrier gas, thus forming a second concentration;
means for cooling the first stage so as to resume accumulating therein for a period of time sample substances carried thereinto by the carrier gas;
means for heating the second stage so as to release said second concentration into the carrier gas flow in the form of a second concentration pulse, said second concentration pulse being more compact in distance and of shorter duration than said first concentration pulse;
and
means for cooling the second stage.

10 more elements

Dependencies are inferred from the claim text.