Automatic titrator

Patent metadata

Field	Value
Publication number	US-9766183-B2
Application number	US-201414489215-A
Country	US
Kind code	B2
Filing date	Sep 17, 2014
Priority date	Sep 17, 2014
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

The present invention generally relates to continuous methods quantifying a target analyte concentration in a process solution. These methods are continuous automated titration methods that use titration chemistries to measure the target analyte concentration in the process solution. The method steps provide for efficient and robust automated titration methods for a variety of target analytes.

First claim

What is claimed is:

1. A method for quantification of a target analyte concentration in a process solution comprising:
continuously flowing and continuously refreshing the process solution at a known flow rate through an analyzer comprising a manifold and a detector;
quantifying the target analyte concentration by continuously adding a titrant to the analyzer and setting a titrant concentration by changing the titrant concentration through increasing or decreasing a flow rate of the titrant over a specified range; and
detecting a titration endpoint for the reaction between the target analyte and the titrant within a specified target analyte concentration range.

2. The method of claim 1 further comprising continuously adding a conditioning reagent to the process solution in a concentration proportional to the target analyte concentration.

3. The method of claim 2 wherein the titrant concentration change is stepwise and is a larger concentration change per step at the beginning of the reaction of the target analyte with the titrant and decreases gradually to a smaller concentration change per step as the reaction proceeds towards the endpoint.

4. The method of claim 2 wherein the titration endpoint is signaled by a detectable change at a complete reaction of the target analyte with the titrant.

5. The method of claim 4 wherein the detectable change is a spectrophotometric change, an electrochemical change, or a pH change.

6. The method of claim 2 wherein the conditioning reagent comprises potassium iodide, acetic acid, starch indicator, or a combination thereof.

7. The method of claim 1 further comprising
(a) determining an estimated target analyte concentration,
(b) estimating the titrant concentration based on the estimated target analyte concentration to obtain an estimated titrant concentration,
(c) introducing the titrant at a titrant flow rate calculated based on the estimated titrant concentration,
(d) detecting an actual target analyte concentration or a concentration of a product produced by the reaction of the analyte and titrant, and
(e) determining whether the actual target analyte concentration is greater than the estimated target analyte concentration, and if the actual target analyte concentration is greater than the estimated target analyte concentration then reporting the actual target analyte concentration.

8. The method of claim 7 wherein in step (e), if the actual target analyte concentration is less than the estimated target analyte concentration, the estimated target analyte concentration is decreased and steps (c), (d), and (e) are repeated with a lower estimated target analyte concentration until the actual target analyte concentration is greater than the estimated target analyte concentration.

9. The method of claim 1 further comprising
(a) determining a low estimated target analyte concentration and a high estimated target analyte concentration,
(b) calculating a low flow rate of the titrant based on the low estimated target analyte concentration and a high flow rate of the titrant based on the high estimated target analyte concentration,
(c) introducing the titrant at the low flow rate,
(d) detecting an actual target analyte concentration, and
(e) determining whether the actual target analyte concentration is greater than or equal to the low estimated target analyte concentration, and if the actual target analyte concentration is greater than or equal to the low estimated target analyte concentration then introducing the titrant at the high flow rate of the titrant, and determining whether the actual target analyte concentration is less than or equal to the high estimated target analyte concentration and if the actual target analyte concentration is less than or equal to the high estimated target analyte concentration then report the actual target analyte concentration is between the low estimated target analyte concentration and the high estimated target analyte concentration.

10. The method of claim 9 wherein step (e) comprises
determining whether the actual target analyte concentration is greater than or equal to the low estimated target analyte concentration, and if the actual target analyte concentration is greater than or equal to the low estimated target analyte concentration then introducing the titrant at the high flow rate of the titrant, and determining whether the actual target analyte concentration is less than or equal to the high estimated target analyte concentration and if the actual target analyte concentration is not less than or equal to the high estimated target analyte concentration then reporting the actual target analyte concentration is greater than the high estimated target analyte concentration.

11. The method of claim 9 further comprising determining whether the actual target analyte concentration is greater than or equal to the low estimated target analyte concentration, and if the actual target analyte concentration is not greater than or equal to the low estimated target analyte concentration, then reporting that the actual target analyte concentration is less than the low estimated target analyte concentration.

12. The method of claim 1 further comprising
(a) determining a first low estimated target analyte concentration and a first high estimated target analyte concentration,
(b) determining a test precision value,
(c) calculating a first test range of the difference between the first high estimated target analyte and the first low estimated target analyte concentration, and
(d) determining whether the test precision value is greater than the first test range, and if the test precision value is greater than the first test range, then reporting the value.

13. A method for quantification of a target analyte concentration in a process solution comprising:
continuously flowing the process solution through an analyzer;
quantifying the target analyte concentration by continuously adding a titrant to the analyzer and setting a titrant concentration change by changing the titrant concentration through increasing or decreasing a flow rate of the titrant over a specified range; and
detecting a titration endpoint for the reaction between the target analyte and the titrant within a specified target analyte concentration range,
further comprising
(a) determining a first low estimated target analyte concentration and a first high estimated target analyte concentration,
(b) determining a test precision value,
(c) calculating a first test range of the difference between the first high estimated target analyte and the first low estimated target analyte concentration, and
(d) determining whether the test precision value is greater than the first test range, and if the test precision value is greater than the first test range, then reporting the value, and wherein step (d) is as follows and further comprising steps (e)-(i)
(d) determining whether the test precision value is greater than the first test range, and if the test precision value is not greater than the first test range, then calculating a first test range midpoint,
(e) calculating a first midpoint flow rate of the titrant based on the first test range midpoint of the estimated target analyte concentration,
(f) introducing the titrant at the first midpoint flow rate,
(g) determining whether the endpoint of the reaction between the target analyte and the titrant can be detected, and if the endpoint can be detected, setting a second high estimated target analyte concentration to the first test range midpoint,
(h) calculating a second test range of the difference between the second high estimated target analyte and th

Assignees

• Ecolab Usa Inc

Inventors

• Kraus Paul R
• Ryther Robert

Classifications

• G01N2021/754

  Reagent flow and intermittent injection of sample or vice versa · CPC title

• G01N21/79 Primary

  Photometric titration · CPC title

• G01N31/166

  Continuous titration of flowing liquids · CPC title