METHOD FOR EXTENDING THE DYNAMIC RANGE OF ABSORBANCE DETECTORS

• US 20160054275A1
• Filed: 03/19/2014
• Published: 02/25/2016
• Est. Priority Date: 03/26/2013
• Status: Active Grant

• Current Assignee: Waters Technologies Corporation (Waters Corporation)
• Original Assignee: Waters Technologies Corporation (Waters Corporation)
• Inventors: ANDREWS, Richard W.
• Granted Patent: US 10,551,362 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 2030/862 Other mathematical operations for data preprocessing
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/3103 Atomic absorption analysis
• CPC Class Codes: G01N 21/59 Transmissivity G01N21/25 takes precedence
• CPC Class Codes: G01N 2201/127 Calibration; base line adjustment; drift compensation
• CPC Class Codes: G01N 30/74 Optical detectors measurement of intensity, velocity, spectral content, polarisation, or phase of infrared, visible or ultraviolet light G01J
• CPC Class Codes: G01N 30/8631 Peaks
• CPC Class Codes: G01N 30/8665 for calibrating the measuring apparatus

Abstract

The invention generally provides methods for improving the dynamic range of an absorbance detector and absorbance detectors having improved dynamic range. In an exemplary embodiment, the method includes receiving calibration data for a plurality of samples, the calibration data comprising an absorbance for a concentration of each of the samples, calculating a contribution of stray light to the calibration data, and correcting subsequent data by removing the contribution of stray light.

Claims

1. A method for measuring the concentration of a sample comprising:

receiving absorbance data from a sample;

receiving calibration data, the calibration data comprising a contribution of stray light to the absorbance data;

correcting the absorbance data by removing at least a portion of the contribution of stray light to the absorbance data;

calculating a concentration of the sample based on the corrected absorbance data.

2. The method of claim 1, wherein correcting the absorbance data by removing the contribution of stray light to the absorbance data comprises:

transforming the absorbance data based on a relationship between absorbance and stray light, wherein that relationship is expressed by the equation set forth below;

3. The method of claim 1, further comprising:

providing an absorbance detector, the absorbance detector comprising

a flow cell having a chamber configured to receive the sample, the flow cell being configured to provide a light path through the sample, the light path having a path length,

a light source configured to direct light into the flow cell and into the light path through the sample, and

a photodetector configured to receive light from the light path through the sample and output a signal based on the received light.

4. The method of claim 3, wherein the absorbance detector is configured to (i) remove a contribution of stray light from the photodetector signal and (ii) output a corrected signal.

5. The method of claim 4, wherein the absorbance detector further comprises a processor in communication with a memory, the processor configured to (i) receive the contribution of stray light to an absorbance of the sample, (ii) store the contribution of stray light in the memory, (iii) receive the photodetector signal, (iv) transform the photodetector signal to remove the contribution of stray light therefrom, and (v) output the corrected signal.

6. The method of claim 1, wherein correcting subsequent data by removing the contribution of stray light provides a gain in the range of about 1.5 AU to about 2.1 AU.

7. A method for improving dynamic range of an absorbance detector comprising:

receiving calibration data for a plurality of samples, the calibration data comprising an absorbance for a concentration of each of the samples;

calculating a contribution of stray light to the calibration data;

correcting subsequent data by removing at least a portion of the contribution of stray light.

8. The method of claim 7, wherein calculating a contribution of stray light to the calibration data comprises:

regressing the set of calibration data against a relationship between concentration and absorbance, wherein the relationship includes the contribution of stray light to the absorbance of the samples.

9. The method of claim 8, wherein the relationship between concentration and absorbance is expressed by the equation set forth below:

10. The method of claim 7, wherein correcting subsequent data by removing the contribution of stray light comprises:

receiving subsequent data for a sample;

receiving a contribution of stray light to the absorbance of the sample;

transforming an absorbance of the subsequent data based on a relationship between absorbance and stray light.

11. The method of claim 10, wherein the relationship between absorbance and stray light is expressed by the equation set forth below:

12. The method of claim 7, further comprising:

providing an absorbance detector, the absorbance detector comprising

a flow cell having a chamber configured to receive a sample, the flow cell being configured to provide a light path through the sample, the light path having a path length,

a light source configured to direct light into the flow cell and into the light path through the sample

a photodetector configured to receive light from the light path through the sample.

13. An absorbance detector comprising:

a flow cell having a chamber configured to receive a sample, the flow cell being configured to provide a light path through the sample, the light path having a path length,

a light source configured to direct light into the flow cell and into the light path through the sample, and

a photodetector configured to receive light from the light path through the sample and output a signal based on the received light;

wherein the absorbance detector is configured to (i) remove a contribution of stray light from the photodetector signal and (ii) output a corrected signal.

14. The absorbance detector of claim 13, further comprising:

a processor in communication with a memory, the processor configured to (i) receive a contribution of stray light to an absorbance of the sample, (ii) store the contribution of stray light in the memory, (iii) receive the photodetector signal, (iv) transform the photodetector signal to remove the contribution of stray light therefrom, and (v) output the corrected signal.

15. The absorbance detector of claim 13, wherein the photodetector signal processor is configured to transform the photodetector signal based on a relationship between absorbance and stray light expressed by the equation set forth below:

16. The absorbance detector of claim 13, wherein the photodetector signal comprises a measure of an absorbance of the sample.

17. The absorbance detector of claim 13, wherein the corrected signal provides a gain in the range of about 1.5 AU to about 2.1 AU.