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Title: Liquid chromatography/Fourier transform IR spectrometry interface flow cell

Abstract

A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

Inventors:
 [1];  [2]
  1. (Fairfield, OH)
  2. (Blacksburg, VA)
Publication Date:
Research Org.:
Virginia Tech Intellectual Properties, Inc. (Blacksburg, VA)
OSTI Identifier:
866031
Patent Number(s):
US 4618769
Assignee:
United States of America as represented by United States (Washington, DC) NETL
DOE Contract Number:
FG22-81PC40799
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
liquid; chromatography; fourier; transform; spectrometry; interface; flow; cell; zero; dead; volume; zdv; microbore; performance; hplc; infrared; ftir; transparent; crystal; diameter; bore; therein; sample; passed; metal; holder; combination; pair; inner; compressible; seals; directly; coupling; configured; spectrometric; outlet; column; fitting; minimize; transfer; effluents; exiting; exhibit; excellent; characteristics; due; essentially; unencumbered; open-flow; design; beam; passes; transverse; circular; preferably; comprised; potassium; bromide; kbr; calcium; fluoride; caf; interference; patterns; vignetting; encountered; conventional; parallel-plate; cells; pathlength; lensing; effect; cross-section; refractive; index; differences; solvent; serve; focus; enhancing; detection; sensitivity; magnitude; performance liquid; detection sensitivity; liquid chromatograph; preferably comprised; interference pattern; beam passes; dead volume; refractive index; flow cell; fourier transform; liquid chromatography; beam path; calcium fluoride; sample detection; zero dead; circular bore; sample volume; transparent crystal; transform infrared; interference patterns; bore therein; sample flow; spectrometry interface; circular cross-section; flow characteristics; hplc column; interface flow; preferably comprise; directly coupling; /250/356/

Citation Formats

Johnson, Charles C., and Taylor, Larry T. Liquid chromatography/Fourier transform IR spectrometry interface flow cell. United States: N. p., 1986. Web.
Johnson, Charles C., & Taylor, Larry T. Liquid chromatography/Fourier transform IR spectrometry interface flow cell. United States.
Johnson, Charles C., and Taylor, Larry T. Wed . "Liquid chromatography/Fourier transform IR spectrometry interface flow cell". United States. doi:. https://www.osti.gov/servlets/purl/866031.
@article{osti_866031,
title = {Liquid chromatography/Fourier transform IR spectrometry interface flow cell},
author = {Johnson, Charles C. and Taylor, Larry T.},
abstractNote = {A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1986},
month = {Wed Jan 01 00:00:00 EST 1986}
}

Patent:

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  • This patent describes a Fourier transform infrared spectrometer. A sample material is isolated by liquid chromatography and directed through an elongated tube of small inner diameter for irradiation by an infrared beam in obtaining an infrared spectrum of the sample material representing the composition thereof. A sample flow cell comprises: a generally cylindrical crystal having a longitudinal axis and a generally circular cross-section. The crystal is transparent to infrared radiation and is positioned in line with the infrared beam. Its longitudinal axis is aligned generally perpendicular to the infrared beam, whereby the infrared beam is incident upon the crystal andmore » is focused generally on the crystal's longitudinal axis and is transmitted therethrough so as to exit therefrom; and a small diameter, linear bore having a circular cross-section positioned within the crystal along the longitudinal axis and extending the length thereof and oriented generally perpendicular to the direction of propagation of the infrared beam therein. The bore is coupled to the elongated tube for receiving and directing the sample material in the path of the infrared beam. The exiting infrared beam includes the infrared spectrum of the sample material.« less
  • A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IRmore » beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.« less
  • The further development of a method for on-line aqueous-based reversed-phase high-performance liquid chromatography/Fourier transform infrared spectrometry is described. An improved interface device based upon the postcolumn extraction of solutes into a proper analyte fluid has been constructed. In this fashion, the coupling of the separation to the spectrometer maintains the developed chromatographic resolution and yet retains the spectral integrity of each analyte with modest interferences. The device allows the detection of solutes within the time frame of the chromatographic separation. The apparent limit of detection for compounds containing carbonyl functionalities is on the order of micrograms per component as minimummore » injectable quantities.« less
  • Fourier transform infrared spectrometry (FTIR) has been used as a detector for microbore high-performance liquid chromatography (HPLC) through the use of a low volume transmission flow cell. Characteristics of the system have been determined and compared with analytical scale HPLC separations with FTIR detection. Improvement in sensitivity is reported for the microbore scale system over the analytical scale system. Direct comparison of the detection limits considering equal quantities injected for 2,6-di-tert-butylphenol is made for both systems. 9 figures, 1 table.
  • The separation of coal liquids by SEC is easily achieved with appropriate columns. Because coal-derived mixtures have several components of a similar size, the use of SEC alone is not adequate for the purpose of identification. Gas chromatography (GC) coupled with mass spectrometry (MS) has been used in conjunction with the SEC. The use of these three analytical techniques (SEC, GC, and MS) is a powerful analytical method for the analysis of the distillables of coal liquids, recycle solvents and anthracene oils. Analysis of SEC fractions of nondistillables by FT-IR spectrometry is very useful in characterizing the coal liquids producedmore » under different reaction conditions. Conventional FT-IR techniques are rather unreliable as well as time consuming, because the mass of coal liquid in a SEC fraction is very small. A new technique, which is more reliable and requires less time than the conventional techniques, is developed for the analysis of small samples. The residues from SEC fractions are spotted onto a potassium bromide (KBr) pellet. The spotted samples are then analyzed using a narrow focused beam in the Microbeam accessory of a Nicolet 60 SXR FT-IR spectrometer. The paper discusses the analytical technique as well as the FT-IR spectra of SEC fractions.« less