Method and apparatus for quantifying solutions comprised of multiple analytes
A multi-analyte sensor system based on hollow core photonic bandgap fiber and Raman anti-Stokes spectroscopy. The system includes: i) an inlet to introduce an analyte sample into an analyzer chamber which analyzer includes; ii) a measurement system to derive the anti-Stokes spectral peaks and/or spectra of the sample; iii) a set of reference calibrants corresponding to the analytes of which the sample is primarily comprised; iv) a second inlet to introduce said calibrants into the analyzer chamber; v) a second measurement system to derive the anti-Stokes spectral peaks and/or spectra of the calibrants vi) an outlet through which the sample and calibrants are expelled from the analyzer chamber.
1. An analyzer system for determining the identity and concentration of at least one target analyte present in a gaseous or liquid sample utilizing the Raman optical scattering effect, the analyzer system comprising:
(i) a laser light source emitting light which generates Raman Stokes and anti-Stokes emissions when incident on the target analyte;
(ii) one or more hollow core photonic band-gap (HCPBG) fibers optically connected to the laser light source, HCPBG fibers including:
(a) a first inlet permitting introduction of a sample containing the target analyte into the HCPBG fibers; and
(b) at least one reference calibrant in the HCPBG fibers, the reference calibrant corresponding to an analyte in the sample;
(iii) a pump configured to inject the sample containing the target analyte into the core of the HCPBG fiber; and
(iv) a spectral analysis system optically coupled to the HCPBG fibers and configured to derive the Raman anti-Stokes spectral peaks and/or spectra of the reference calibrant to establish a baseline response and account for cross sensitivities or spectral peak overlaps in the sample.
2. The system of claim 1 , where the one or more HCPBG fibers comprise a single HCPBG fiber that has multiple hollow channels, wherein at least one of the hollow channels is pre-filled with the reference calibrant.
3. The system of claim 1 , where the one or more HCPBG fibers comprise two or more HCPBG fibers wound in parallel along a mandrel, where at least one of the HCPBG fibers comprises the reference calibrant, the system further comprising a coupler which switches the laser light source output from one fiber to the other.
4. The system of claim 1 , where the one or more HCPBG fibers comprise a single HCPBG fiber having two or more parallel channels wound along a mandrel, where at least one of the channels comprises the reference calibrant, the system further comprising a coupler which switches the laser light source output from one fiber channel to the other.
5. The system of claim 1 , where the spectral analysis system comprises at least one optically filtered photo-detector and/or optically filtered photo-detector array.
6. The system of claim 1 , further comprising a sample filtration system through which the sample passes before being introduced into the one or more HCPBG fibers.
7. The system of claim 1 , wherein the sample contains a plurality of analytes having known concentrations.
8. The system of claim 1 , further comprising a monitor which measures an amplitude of the laser light source before it is introduced into the one or more HCPBG fibers.
9. The system of claim 1 , wherein the spectral analysis system further comprises a monitor which measures a magnitude of the laser light source, the Raman Stokes emission signals, and the Raman anti-Stokes emission signals after exit from the one or more HCPBG fibers and thereby determines the scattering and/or absorption loss.
10. The system of claim 1 , further comprising means for determining the concentration of the target analyte or other analytes in the sample using multi-variate analysis of the Raman anti-Stokes spectra and corresponding training sets.
11. The system of claim 1 , further comprising means for determining the concentration of the target analyte or other analytes in the sample using univariate analysis of the Raman anti-Stokes spectra and the corresponding calibrant spectra.
12. The system of claim 1 , wherein the laser light source emits light in the range of 350 to 850 nm.
13. A system for the determination of the concentration of at least one target analyte present in a gaseous or liquid sample using Raman anti-Stokes radiation spectroscopy the system comprising:
(a) a laser pump light source;
(b) an inlet for the laser pump light source into one or more hollow core photonic band gap (HCPBG) fibers, the HCPBG fibers operating in a fundamental mode or a limited number of modes, the HCPBG fibers configured to contain a reference calibrant;
(c) a pump configured to introduce the sample containing the at least one target analyte into the core of the HCPBG fiber via an inlet port;
(d) a spectral analysis system comprising at least one filter and/or dispersive element and a detector array or CCD including means for detecting and quantifying Raman anti-Stokes spectrum and/or spectral peaks emitted by the reference calibrant to establish a baseline response and account for cross sensitivities or spectral peak overlaps in the sample when illuminated by the laser pump light source;
(e) means for optically coupling components (a) and (d) to the core of the HCPBG fiber.
14. The system of claim 13 , where the laser pump light source includes an amplitude monitor.
15. The system of claim 13 , further comprising means for monitoring the amplitudes of the signals that exit the hollow core photonic bandgap fiber and account for scattering and/or absorption loss of the Raman anti-Stokes signal.
16. A method of determining the identity and concentration of at least one target analyte present in a gaseous or liquid sample utilizing the Raman optical scattering effect, the method comprising:
exciting a reference calibrant in one or more hollow core photonic band-gap (HCPBG) fibers, using an excitation light source, the reference calibrant corresponding to a target analyte in a sample;
as a result of exciting the at least one reference calibrant, deriving the Raman anti-Stokes spectral peaks and/or spectra of the reference calibrant to establish a baseline response, using a spectral analysis system optically coupled to the HCPBG fibers;
introducing the sample containing the target analyte into the one or more HCPBG fibers though an inlet in fluid communication with a hollow core of the HCPBG fibers;
exciting the sample using the excitation light source;
as a result of exciting the sample containing the target analyte, deriving the Raman anti-Stokes spectral peaks and/or spectra of the target analyte from the Raman anti-Stokes light received and accounting for cross sensitivities or spectral peak overlaps in the sample containing the target analyte; and
expelling the sample containing the target analyte from the hollow core of the HCPBG fibers.
17. The method of claim 16 , further comprising determining a concentration of the target analyte in the sample using multi-variate analysis of the Raman anti-Stokes spectra and corresponding training sets.
18. The method of claim 16 , further comprising switching the excitation light source from a fiber having the reference calibrant to a different fiber having the sample.
19. The method of claim 16 , further comprising measuring an amplitude of the excitation light source before it is introduced into the one or more HCPBG fibers.
20. The method of claim 16 , further comprising measuring the magnitude of signal from the excitation light source, the Raman Stokes emission signals, and the Raman anti-Stokes emission signals after exit from the one or more HCPBG fibers and thereby determining scattering and/or absorption loss.