Dual Matrix Chlorine Dioxide Test Device
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Solution Overview
Problem
Existing test devices for semi-quantitative determination of chlorine dioxide in liquid samples struggle to accurately measure concentrations due to interference from free chlorine, which affects the color change of redox indicators, limiting their effectiveness in determining chlorine dioxide concentrations within specified limits.
Innovation Solution
A test device with two carrier matrices, one containing amino acid, sodium thiosulfate, redox indicator, and surfactant, and the other with inorganic iodide salt, starch, and sodium thiosulfate, allowing for a broader measuring range of 10-3500 mg/L chlorine dioxide while suppressing interference from free chlorine, using specific molar ratios and inert dyes for clear color differentiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single carrier matrix with redox indicator is used, then the test device is simple and easy to operate, but the measuring range is limited and interference from free chlorine cannot be suppressed
Solution Approach 1:
The test device is divided into two separate carrier matrices, each optimized for different measuring ranges (10-2000 mg/L and 2000-3500 mg/L). This segmentation allows each matrix to be specifically tuned for its range while collectively covering a broader overall range, resolving the contradiction between versatility and complexity.
Solution Approach 2:
The test device achieves multi-functionality by incorporating two carrier matrices that can collectively measure across a wide range (10-3500 mg/L) of chlorine dioxide concentrations. Each matrix serves multiple purposes: the first matrix covers lower concentrations while the second covers higher concentrations, creating a universal testing solution.
2Measurement precision
If free chlorine is present in the liquid sample, then the redox indicator shows color change due to oxidation, but this interference prevents accurate determination of chlorine dioxide concentration
Solution Approach 1:
Each carrier matrix is formulated with specific local qualities - different compositions of amino acids, redox indicators, and sodium thiosulfate - that make them selectively responsive to chlorine dioxide while being resistant to free chlorine interference. The first matrix is optimized for 10-2000 mg/L range and the second for 2000-3500 mg/L, with each having tailored chemical properties for its specific measuring range.
Solution Approach 2:
Sodium thiosulfate acts as an intermediary substance that selectively reacts with free chlorine to prevent it from oxidizing the redox indicator. This mediator suppresses the harmful interference from free chlorine while allowing the redox indicator to respond specifically to chlorine dioxide, thereby improving measurement precision.
3Adaptability or versatility
If the measuring range is extended to cover both low and high concentrations, then more applications are covered, but the color differentiation becomes less clear
Solution Approach 1:
The broad measuring range (10-3500 mg/L) is segmented into two distinct ranges, each handled by a separate carrier matrix. The first matrix provides clear color differentiation for 10-2000 mg/L, while the second matrix provides clear differentiation for 2000-3500 mg/L. This segmentation maintains color differentiation clarity within each range while achieving broad overall coverage.
Solution Approach 2:
Each carrier matrix is given local quality optimized for its specific measuring range through selective composition of redox indicators and amino acids. This allows each matrix to exhibit optimal color differentiation characteristics for its designated range, preventing the degradation of color differentiation that would occur if a single matrix attempted to cover the entire range.
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
The test device provides a significantly larger measuring range for chlorine dioxide, effectively differentiating concentrations from 10-2000 mg/L on the first matrix and 2000-3500 mg/L on the second, while preventing interference from free chlorine up to 1000 mg/L, simplifying handling and improving accuracy.
Implementation Method 1
the first carrier matrix containing at least one amino acid, sodium thiosulfate, at least one redox indicator, buffer substances and at least one surfactant
Implementation Method 2
the combination of amino acid and sodium thiosulfate makes it possible to suppress interference compared to 1000 mg/L free chlorine
Implementation Method 3
the second carrier matrix containing at least one inorganic iodide salt, starch and/or at least one starch derivative
Data Source
AI summary
The present invention relates to a test apparatus (1) for the semi-quantitative determination of chlorine dioxide in a liquid sample, wherein the test apparatus comprises at least two support matrices (2, 3), the first support matrix (2) containing at least one amino acid, sodium thiosulfate, at least one redox indicator, buffer substances, and at least one surfactant, and the second support matrix (3) containing at least one inorganic iodide salt, starch and/or at least one starch derivative, sodium thiosulfate, buffer substances, and at least one surfactant. The invention further relates to a method for the semi-quantitative determination of chlorine dioxide in a liquid sample containing free chlorine, comprising: a) contacting the liquid sample with both support matrices (2, 3) of a test apparatus (1) according to one of the preceding claims; b) comparing the color of both support matrices (2, 3) with a color scale to read the chlorine dioxide concentration.