Method and system for examining the composition of a fluid or solid sample ...

[54] METHOD AND SYSTEM FOR EXAMINING THE COMPOSITION OF A FLUID OR SOLID SAMPLE USING FLUORESCENCE AND/OR ABSORPTION SPECTROSCOPY

[75] Inventors: Jonathan E. Kenny, Lexington, Mass.;

Todd A. Taylor, Chittenden, Vt.

[73] Assignee: Tufts University, Medford, Mass.

[21] Appl. No.: 160,514
[22] Filed: Dec. 1,1993

[51] Int. CI.6 G01N 21/64

[52] U.S. CI 250/461.1; 250/459.1

[58] Field of Search 250/461.1, 459.1;

356/317, 318

[56] References Cited

U.S. PATENT DOCUMENTS

4,916,319 4/1990 Telfair et al 250/461.1

5,149,026 9/1992 Fay et al 250/461.1

5,274,240 12/1993 Mathies et al 250/461.1

5,303,026 4/1994 Strobl et al 250/318

5,304,492 4/1994 KUnkhammer 250/461.1

OTHER PUBLICATIONS

Johnson et al., "Video fluorometer," Rev. Sci. Instrum., vol. 50(1), pp. 118-126 (Jan. 1979).

Hershberger et al., "Sub-Microliter Flow-Through Cuvette
for Fluorescence Monitoring of High Performance Liquid
Chromatographic Effluents," Analytical Chemistry, vol. 51,
No. 9, pp. 1444-1446 (Aug. 1979).
Nir et al., "CCD detectors record multiple spectra simulta-
neously," Laser Focus World, pp. 111-120 (Aug. 1991).
Hershberger et al., "Liquid Chromatography with
Real-Time Video Fluorometric Monitoring of Effluents,"
Anal. Chem., vol. 53, pp. 971-975 (1981).
Skoropinski et al., "Laser Videofluorometer System for
Real-Time Characterization of High-Peformance Liquid
Chromatographic Eluate," Anal. Chem., vol. 58, pp.

2831-2839 (1986).

Primary Examiner—Davis L. Willis
Assistant Examiner—Richard Hanig
Attorney, Agent, or Firm—Kriegsman & Kriegsman

[57] ABSTRACT

A method and system for examining the composition of a fluid or solid sample using fluorescence and/or absorption spectroscopy. In one embodiment, the system is adapted for use in examining liquid effluents as they elute from the end of a liquid chromatography column and comprises a Nd: YAG laser coupled to a harmonic generator. Pulses of the fourth harmonic therefrom are focused into a Raman shifter filled with a mixture of hydrogen and methane gases. The laser pulses have an intensity sufficient to produce an array of different-colored laser pulses by stimulated Raman scattering within the Raman shifter. These different-colored pulses are then dispersed according to their respective wavelengths and then launched into a plurality of optical fibers. The fibers tranmit the different-colored pulses to a specially-designed detection cell, where they simultaneously excite a flowing fluid sample contained within the cell at the same point of axial fluid flow. The fluid sample enters and exits the detection cell via tubes. Ultraviolet and visible lamp light is also used to illuminate the fluid sample, and the attenuation of this light is used to obtain an absorption spectrum of the sample. Optical fibers are used to transport fluorescent light, transmitted lamp light and a fraction of the Raman-shifted laser light to an imaging spectrograph. The light from each optical fiber is dispersed along a narrow strip by the spectrograph to produce an array of strips, each strip corresponding to one of the fibers, and is focused on the surface of a 2-dimensional CCD detector. The CCD detector converts each strip into electrical charges, which are digitized and processed by a computer to create an EEM. The aforementioned system is capable of obtaining an absorption spectrum from 200-479 nm with 0.5-5 nm • spectral resolution and 10 fluorescence spectra simultaneously every 0.1-250 seconds for several hours, with crosstalk between channels of less than 10-4.

25 Claims, 11 Drawing Sheets