Nitrate Measurement Using Water-Soluble Thioether Reduction
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Solution Overview
Problem
Current methods for measuring aqueous nitrate concentration, such as colorimetric tests, face challenges including toxicity of reagents like cadmium, variability due to shaking requirements, and limitations in using solid reagents in portable testing equipment, which affect sensitivity and selectivity.
Innovation Solution
A method using water-soluble thioethers and catalysts, like MoO2Cl2 with a Cu2+ co-catalyst, to reduce nitrate to nitrite, followed by a Griess reagent system for color generation, allowing for accurate nitrate concentration measurement without toxic metals and shaking, and enabling deposition on portable test elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cadmium is used to reduce nitrate to nitrite, then nitrate concentration can be measured, but toxicity and variability issues arise
Solution Approach 1:
The patent introduces an intermediary substance (the test element with deposited reagents) that facilitates the reduction of nitrate to nitrite without requiring direct contact with toxic cadmium metal. The reagents are deposited on the test element surface, allowing the reduction reaction to occur in aqueous solution without the need for solid cadmium reagents, thus eliminating toxicity while maintaining measurement capability
Solution Approach 2:
The patent changes the physical state of the reagents from solid (cadmium metal) to aqueous solution form deposited on the test element. This parameter change allows the reagents to be used in portable equipment while eliminating the need for shaking and reducing variability, as the reagents are already in solution form on the test element surface
2Measurement precision
If solid reagents like cadmium are used, then nitrate reduction can be achieved, but they cannot be used in portable testing equipment
Solution Approach 1:
The test element serves as an intermediary carrier that holds the aqueous reagents in a deposited form. This allows the reagents to be transported and stored in portable equipment without requiring solid cadmium, as the aqueous solution is already deposited on the test element surface, making the system adaptable to portable devices
Solution Approach 2:
The patent uses aqueous solution form for the reagents, allowing them to be deposited on the test element surface. This hydraulic form (liquid/aqueous) enables the reagents to be used in portable equipment with fluid handling capabilities, eliminating the need for solid reagent handling mechanisms
3Productivity
If shaking is required in cadmium-containing systems, then nitrate reduction can proceed, but surface reaction variability increases
Solution Approach 1:
The patent changes the physical state of reagents from solid to aqueous solution deposited on the test element. This eliminates the need for shaking to facilitate contact between reagents and nitrate, as the aqueous reagents are already in solution form on the test element surface, ensuring consistent and reliable testing results without variability
Solution Approach 2:
The reagents are pre-deposited on the test element surface before use. This preliminary action ensures that the reagents are already in the correct position and form (aqueous solution) to react with nitrate immediately upon contact, eliminating the need for shaking and ensuring consistent, reliable testing results
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 approach eliminates toxic metals, reduces variability, enhances selectivity, and allows for portable, accurate nitrate concentration measurement within a range of 0 to 15 ppmw, tailored reaction rates, and improved water solubility of reagents.
Implementation Method 1
The sulfoxidation of thioethers with nitrate as the oxidant and a homogeneous Mo/Cu(II) co-catalyst system has been reported as a pathway to sulfoxides in organic solvent such as acetonitrile
Implementation Method 2
nitrate is first reduced to nitrite, followed by nitrite analysis
Implementation Method 3
in the presence of a water soluble catalyst, and a water soluble reagent system adapted to interact with nitrite
Implementation Method 4
nitrite concentration is determined using the Griess assay or test
Implementation Method 5
a water soluble reagent system adapted to interact with nitrite to generate a color
Data Source
AI summary
A method of measuring nitrate concentration in an aqueous sample includes mixing the aqueous sample with a water-soluble thioether chosen to reduce nitrate in the aqueous sample to nitrite in the presence of a water soluble catalyst, and a water soluble reagent system adapted to interact with nitrite to generate a color; measuring color generation, and correlating the color generation to nitrate concentration.