US-20260126418-A1 - Split Flow Modulator for Comprehensive Two-Dimensional Chromatography

US20260126418A1US 20260126418 A1US20260126418 A1US 20260126418A1US-20260126418-A1

Abstract

A re-sampling device for two-dimensional gas chromatography includes a modulator; a splitter disposed upstream from the modulator and configured to split an effluent from a primary column and deliver a portion of the effluent to waste and a portion of the effluent to the modulator; a first accumulating loop; a second accumulating loop; a first switch configured to selectively deliver the effluent from the splitter to one of the first accumulating loop or the second accumulating loop; and a second switch configured to selectively deliver the effluent from the one of the first accumulating loop or the second accumulating loop to a secondary column.

Inventors

Leonid M. Blumberg

Assignees

LECO CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251230

Claims (20)

1 . A re-sampling device for two-dimensional gas chromatography, the re-sampling device comprising: a modulator; a splitter disposed upstream from the modulator and configured to split an effluent from a primary column and deliver a portion of the effluent to waste and a portion of the effluent to the modulator; a first accumulating loop; a second accumulating loop; a first switch configured to selectively deliver the effluent from the splitter to one of the first accumulating loop or the second accumulating loop; and a second switch configured to selectively deliver the effluent from the one of the first accumulating loop or the second accumulating loop to a secondary column.
2 . The re-sampling device of claim 1 , wherein the modulator is one of a representative modulator, a representative thermal modulator, a full transfer flow modulator, a full transfer thermal modulator, a low duty cycle modulator, or a microfluidic flow modulator.
3 . The re-sampling device of claim 1 , further comprising an auxiliary gas supply configured to flush one of the first accumulating loop or the second accumulating loop.
4 . The re-sampling device of claim 3 , wherein when the first switch and the second switch are in a first position, the auxiliary gas supply flushes the first accumulating loop, and when the first switch and the second switch are in a second position, the auxiliary gas supply flushes the second accumulating loop.
5 . The re-sampling device of claim 3 , wherein a portion of the effluent from the primary column is being accumulated in the first accumulating loop while the auxiliary gas supply flushes the second accumulating loop.
6 . The re-sampling device of claim 3 , wherein a portion of the effluent from the primary column is being accumulated in the second accumulating loop while the auxiliary gas supply flushes the first accumulating loop.
7 . The re-sampling device of claim 1 , wherein the first accumulating loop includes a first volume and the second accumulating loop includes a second volume equal to the first volume.
8 . The re-sampling device of claim 1 , wherein the re-sampling device is implemented in a device for two-dimensional gas chromatography including the primary column and the secondary column.
9 . The re-sampling device of claim 1 , wherein the secondary column is downstream from the primary column and the re-sampling device is disposed between the primary column and the secondary column.
10 . The re-sampling device of claim 1 , wherein the splitter is integrally formed with the modulator.
11 . A re-sampling device for two-dimensional gas chromatography, the re-sampling device comprising: a modulator configured to receive an effluent from a primary column; and a splitter disposed downstream from the modulator and configured to split the effluent to deliver a portion of the effluent to waste and a portion of the effluent to a secondary column; a first accumulating loop; a second accumulating loop; a first switch configured to selectively deliver the effluent from the primary column to one of the first accumulating loop or the second accumulating loop; and a second switch configured to selectively deliver the effluent from the one of the first accumulating loop or the second accumulating loop to the splitter.
12 . The re-sampling device of claim 11 , wherein the modulator is one of a representative modulator, a representative thermal modulator, a full transfer flow modulator, a full transfer thermal modulator, a low duty cycle modulator, or a microfluidic flow modulator.
13 . The re-sampling device of claim 11 , further comprising an auxiliary gas supply configured to flush one of the first accumulating loop or the second accumulating loop.
14 . The re-sampling device of claim 13 , wherein when the first switch and the second switch are in a first position, the auxiliary gas supply flushes the first accumulating loop, and when the first switch and the second switch are in a second position, the auxiliary gas supply flushes the second accumulating loop.
15 . The re-sampling device of claim 13 , wherein a portion of the effluent from the primary column is being accumulated in the first accumulating loop while the auxiliary gas supply flushes the second accumulating loop.
16 . The re-sampling device of claim 13 , wherein a portion of the effluent from the primary column is being accumulated in the second accumulating loop while the auxiliary gas supply flushes the first accumulating loop.
17 . The re-sampling device of claim 11 , wherein the first accumulating loop includes a first volume and the second accumulating loop includes a second volume equal to the first volume.
18 . The re-sampling device of claim 11 , wherein the re-sampling device is implemented in a device for two-dimensional gas chromatography including the primary column and the secondary column.
19 . The re-sampling device of claim 18 , wherein the secondary column is downstream from the primary column and the re-sampling device is disposed between the primary column and the secondary column.
20 . The re-sampling device of claim 11 , wherein the splitter is integrally formed with the modulator.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This U.S. patent application is a continuation of, and claims priority under 35 U.S.C. § 120 from, U.S. patent application Ser. No. 17/904,003, filed on Feb. 23, 2021, which is a national phase application of, and claims priority under 35 U.S.C. § 371 from, International Application PCT/US 2021/019186, filed on Feb. 23, 2021, which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application 62/980,752, filed on Feb. 24, 2020. The disclosures of these prior applications are considered part of the disclosure of this application and are hereby incorporated by reference in their entireties. TECHNICAL FIELD This disclosure relates to split flow modulators for comprehensive two-dimensional chromatography. BACKGROUND Gas chromatography (GC) is generally used to characterize complex mixtures of volatile organic compounds (VOCs), which can be key components in industrial, environmental, medical, and other samples. The separating power of GC analysis can be expressed via the number of components that can be separated and identified in a certain time. Increasing the separating power of conventional GC requires a disproportionally large increase in analysis time. Comprehensive two-dimensional gas chromatography (GC×GC) is a way of substantially increasing (e.g., by more than a factor of 10) the separating power of GC without increasing the analysis time. GC-MS instruments (GC with mass spectrometer as a detector) use gas chromatography to separate mixtures into individual components and mass spectrometry to detect and identify each component. Chromatographic separation is the rate-limiting step: complex samples often require more than 30 minutes to resolve (quantifiably and identifiably separate). Chromatography is an analytical method for the separation and identification of chemical compounds from mixtures. The combination of gas chromatography with quantitative instrumentation, e.g., GC-IR (GC with an infrared spectrometer as a detector), GC-UV (GC with an ultraviolet spectrometer as a detector), and GC-MS, may provide reliable results, and combining comprehensive two-dimensional gas chromatography (GC×GC) with these techniques may further increase their separating power. In comprehensive multi-dimensional column chromatography such as GC×GC, LC×LC (liquid chromatography), etc., modulation (also known as sampling and resampling) is a process of dividing the analysis time in small sub-intervals—the modulation periods, or sampling periods—typically of equal duration, and sending, during each period, all or a fraction of the effluent or eluite of the primary column into the secondary column as narrow reinjection pulses having a duration typically substantially shorter than the sampling period. The devices performing this operation are known as modulators or resamplers. The term “effluent” is understood to mean both a carrier gas and an analyte eluting from a column outlet. The term “eluite” is understood to mean the analyte in the effluent. GC×GC modulators are distinguishable by their design principles and functionality. Thermal modulation and flow modulation are common design principles. Two types of functionality of GC×GC modulation can be recognized: (i) snapshot or duty-cycle modulation and (ii) full transfer modulation. A snapshot flow modulator transfers a fraction of the primary effluent to the secondary column during a short fraction of the modulation period. During the remaining portion of the modulation period, the primary effluent goes to waste. The full transfer flow modulator accumulates the entire primary effluent in an accumulating loop (also known as the sample loop) and, at the end of the accumulation, transfers the entire content of the accumulating loop into the secondary column. A full transfer thermal modulation works in a similar way, but it accumulates in the accumulating loop only the primary eluite while the carrier gas eluting from the primary column flows through the accumulating loop. Snapshot modulation may have several disadvantages. Snapshot modulation may not transfer a consistent fraction of the primary eluite to the secondary column. The transferred fraction of the eluite depends on the sampling phase—the time difference between the maximum concentration of the primary eluite and beginning of the transfer of the eluite into the secondary column—that can vary from run to run. In snapshot modulation, the sharpness of the reinjection pulse depends on the timing of starting and ending the sampling of the primary effluent. As the transitions from one state to another cannot be instantaneous, they limit the sharpness of the reinjection pulses and can cause incomplete effluent transfer even during the time of its transfer. In snapshot modulation, the fact that only a fraction of the primary eluite is transferred into the secondary column can substantially reduce detectability of low concentration analytes. This is especially harmful when o