Fluorometric Detection of Dipicolinic Acid in Peracid Solutions

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Solution Overview

Problem

Conventional fluorometers struggle to accurately measure low concentrations of chemicals like dipicolinic acid in cleaning solutions due to interference from strong oxidizers and variability in temperature and pH, leading to inaccurate fluorescence readings.

Innovation Solution

The use of a reducing agent, such as sodium thiosulfate, is introduced to neutralize peracid and peroxide species, combined with the addition of terbium chloride to form a complex with dipicolinic acid, allowing for precise fluorescence detection and overcoming interference issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fluorescence detection is used to measure dipicolinic acid concentration, then the measurement is quick and cost effective, but the accuracy is reduced due to interference from peracids and variability from temperature and pH changes

Engineering Contradiction:
Improvemeasurement speedVSAvoidconcentration measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The method applies preliminary action by adding a reducing agent (such as sodium thiosulfate) to the sample before fluorescence measurement to pre-neutralize peracids and stabilize the pH environment. This preliminary chemical treatment eliminates interfering factors before the actual fluorescence detection occurs, ensuring accurate measurements without sacrificing the quick and cost-effective nature of fluorometric analysis.

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If conventional fluorometers are used to measure low concentrations of dipicolinic acid, then the method remains simple and cost effective, but the sensitivity is insufficient to accurately detect concentrations at the parts per billion level

Engineering Contradiction:
Improvemeasurement system simplicityVSAvoiddetection sensitivity
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The invention applies parameter changes by modifying the chemical environment parameters (pH and oxidizer concentration) through adding reducing agents. This chemical parameter modification enhances the fluorescence signal intensity and stability, enabling conventional fluorometers to detect dipicolinic acid at parts per billion concentrations with high sensitivity while maintaining the simplicity and cost-effectiveness of the measurement system.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If peracids are present in the cleaning composition, then the sanitizing and disinfecting effectiveness is maintained, but the peracids chemically interfere with fluorescence detection and cause variability in measurements

Engineering Contradiction:
Improvesanitizing effectivenessVSAvoidinterference with fluorescence detection
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The method introduces an intermediary substance (reducing agent such as sodium thiosulfate) that mediates between the peracids and the fluorescence detection system. The reducing agent selectively reacts with and neutralizes peracids, eliminating their harmful interfering effect on fluorescence measurement while not affecting the sanitizing effectiveness of the cleaning composition. This intermediary approach resolves the contradiction by protecting the measurement process from peracid interference.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method enables accurate and linear measurement of dipicolinic acid concentrations, even at low levels, by stabilizing the fluorescence signal and eliminating interference from oxidizers, thereby enhancing the sensitivity and reliability of the analysis.

Implementation Method 1

an effective amount of a reducing agent, such as a sulfate, more specifically a thiosulfate is added to an assay sample to eliminate interference with the fluorescent absorbance

Methodology Applied
Scientific EffectRedox reactions: Redox Reactions

Implementation Method 2

dipicolinic acid provides enhanced fluorescence when forming a complex with terbium ions

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 3

when forming a complex with terbium ions, dipicolinic acid provides enhanced fluorescence

Methodology Applied
Scientific EffectComplex formation: Chemical Bonding

Implementation Method 4

a detector adapted to measure the intensity of fluorescence emitted by the electromagnetic radiation

Methodology Applied
Scientific EffectFluorescence emission: Fluorescence

Data Source

PatentEP3403070B1Methods of detecting and quantifying picolinate acid in a peracid composition
Publication Date: 2021.03.03 ECOLAB USA INC
  • EP3403070B1 patent drawingFigure 1
  • EP3403070B1 patent drawingFigure 2
  • EP3403070B1 patent drawingFigure 3

AI summary

A method of fluorometrically detecting the concentration of chemical components in oxidizing formulations is disclosed. In a particular embodiment the detection is of the stabilizing component of picolinic acid, present in such formulations, although any component which fluoresces may be detected. According to the invention sample preparation of the oxidizing formulation includes adding to said sample an excess of reducing agent to bind peracid, and in the case of picolinic acid, adding to said sample an excess of terbium chloride. The sample then is subjected to radiation to induce fluorescence and the concentration of said chemical component is determined by a linear relationship between fluorescence emitted and the concentration of the target chemical.