Liquid chromatography/Fourier transform IR spectrometry interface flow cell
First Claim
1. In a Fourier transform infrared spectrometer wherein 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 comprising:
- a generally cylindrical crystal having a longitudinal axis and a generally circular cross-section, wherein said crystal is transparent to infrared radiation and is positioned in line with the infrared beam with its longitudinal axis aligned generally perpendicular to the infrared beam, whereby said infrared beam is incident upon said crystal and 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 said crystal along the longitudinal axis and extending the length thereof and oriented generally perpendicular to the direction of propagation of the infrared beam therein, said bore coupled to the elongated tube for receiving and directing the sample material in the path of the infrared beam wherein the exiting infrared beam includes the infrared spectrum of the sample material.
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Accused Products
Abstract
A zero dead volume (ZDV) microbore high performance liquid chromatography (μHPLC)/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 μHPLC column end fitting to minimize the transfer volume of the effluents exiting the μHPLC 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 (CaF2), 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.
50 Citations
12 Claims
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1. In a Fourier transform infrared spectrometer wherein 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 comprising:
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a generally cylindrical crystal having a longitudinal axis and a generally circular cross-section, wherein said crystal is transparent to infrared radiation and is positioned in line with the infrared beam with its longitudinal axis aligned generally perpendicular to the infrared beam, whereby said infrared beam is incident upon said crystal and 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 said crystal along the longitudinal axis and extending the length thereof and oriented generally perpendicular to the direction of propagation of the infrared beam therein, said bore coupled to the elongated tube for receiving and directing the sample material in the path of the infrared beam wherein the exiting infrared beam includes the infrared spectrum of the sample material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification