Photothermal absorbance measurement in a flow system

Patent metadata

Field	Value
Publication number	US-11199491-B2
Application number	US-201916564465-A
Country	US
Kind code	B2
Filing date	Sep 9, 2019
Priority date	Sep 7, 2018
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

A photothermal absorbance detection apparatus comprises a flow cell comprising a first temperature responsive device on an input side, a second temperature responsive device on an output side, and a detection region between the first temperature responsive device and the second temperature responsive device; and a light-emitting device positioned proximate to the detection region and configured to transmit electromagnetic radiation towards the detection region; wherein the first temperature responsive device and the second temperature responsive device together measure a change in temperature of a fluid passing through the detection region.

First claim

The invention claimed is:

1. A photothermal absorbance detection apparatus comprising:
a flow cell comprising:
a fluid input tube and an input optical fiber on an input side;
a fluid output tube and an output optical fiber on an output side, wherein the input optical fiber and output optical fiber face each other, with the output optical fiber being configured to receive light emitted from the input optical fiber,
a first temperature responsive device on the input side,
a second temperature responsive device on the output side, and
a detection region between the first temperature responsive device and the second temperature responsive device; and

a light-emitting device positioned proximate to the detection region of the flow cell and configured to irradiate the detection region with electromagnetic radiation;
wherein the first temperature responsive device and the second temperature responsive device together measure a differential temperature change of a fluid passing through the detection region of the flow cell.

2. The apparatus of claim 1 , wherein the first temperature responsive device and the second temperature responsive device each individually are, or together form, a differential temperature sensor comprising a thermocouple, thermopile, thermistor, diode, transistor, or resistor.

3. The apparatus of claim 1 , wherein the first temperature responsive device is a first thermocouple junction and the second temperature responsive device is a second thermocouple junction.

4. The apparatus of claim 3 , wherein:
the first thermocouple junction is positioned proximate to the fluid input tube; and
the second thermocouple junction is positioned proximate to the fluid output tube.

5. The apparatus of claim 3 , wherein the first thermocouple junction and the second thermocouple junction comprise wires having diameters of 25 microns or less.

6. The apparatus of claim 3 , wherein the first thermocouple junction and the second thermocouple junction together comprise a thermocouple.

7. The apparatus of claim 6 , wherein current is generated by the thermocouple based on a difference in temperature between the first thermocouple junction and the second thermocouple junction.

8. The apparatus of claim 7 , wherein the temperature difference is created by analytes present in an analyte-containing fluid passing through the detection region of the flow cell being heated by absorption of electromagnetic radiation transmitted by the light-emitting device.

9. The apparatus of claim 1 , wherein the fluid input tube and the fluid output tube are made from polyetheretherketone (PEEK).

10. The apparatus of claim 1 , wherein the light-emitting device is a broadband emitter or a fixed wavelength emitter.

11. The apparatus of claim 10 , wherein the light-emitting device is a monochromatic laser.

12. A method for detecting the absorbance of analytes in a fluid comprising:
passing an analyte-containing fluid through the flow cell of the photothermal absorbance detection apparatus of claim 1 ;
measuring a temperature difference between the input side and the output side of the flow cell; and
correlating the temperature difference with a concentration of analyte present in the analyte-containing fluid.

13. The method of claim 12 , wherein the first temperature responsive device and the second temperature responsive device each individually are, or together form, a differential temperature sensor comprising a thermocouple, thermopile, thermistor, diode, transistor, or resistor.

14. The method of claim 12 , wherein the first temperature responsive device is a first thermocouple junction and the second temperature responsive device is a second thermocouple junction.

15. The method of claim 14 , further comprising:
measuring a current between the first thermocouple junction and the second thermocouple junction generated by a difference in a first temperature at the first thermocouple junction and a second temperature at the second thermocouple junction; and
correlating the measured current or voltage with a concentration of analyte present in the analyte-containing fluid.

16. The method of claim 15 , further comprising:
irradiating the detection region with electromagnetic radiation from the light-emitting device to heat analytes present in the detection region, whereby the temperature of the analyte-containing fluid in the detection region increases as analytes in the analyte-containing fluid are heated by absorption of the electromagnetic radiation.

17. The method of claim 15 , wherein each of the first thermocouple and the second thermocouple has a diameter of 25 microns or less.

18. The method of claim 15 , wherein absorbance of the electromagnetic radiation by the analytes in the analyte-containing fluid increases the temperature of the analyte-containing fluid passing through the detection region,
wherein a temperature of the analyte-containing fluid on the input side is lower than a temperature on the output side.

19. The method of claim 15 , wherein:
the first thermocouple junction is positioned on the fluid input tube; and
the second thermocouple junction is positioned on the fluid output tube.

Assignees

• Univ Texas

Inventors

• Dasgupta Purnendu
• Chouhan Bikash

Classifications

• G01N2021/1714

  Photothermal radiometry with measurement of emission · CPC title

• G01K7/22

  the element being a non-linear resistance, e.g. thermistor (G01K7/26 takes precedence) · CPC title

• G01N21/05

  Flow-through cuvettes (G01N21/09 takes precedence; handling fluid samples G01N1/10) · CPC title

• G01N2021/1712

  Thermal lens, mirage effect · CPC title

• G01K7/02

  using thermoelectric elements, e.g. thermocouples · CPC title