Diesel Fuel DEF Detection Using Urease and Colorimetric Strips
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Solution Overview
Problem
The contamination of diesel fuel with diesel exhaust fluid (DEF) due to its similarity in appearance to Fuel System Icing Inhibitor (FSII) leads to engine damage and failure, necessitating a method to detect DEF contamination accurately.
Innovation Solution
A method involving a buffered urease solution to convert urea in DEF to ammonia, followed by pH adjustment and reaction with a reagent strip to detect ammonia through color change, using components like urease, sodium phosphate buffer, and iron (III) cyano complexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If DEF is stored in similar containers to FSII for convenience, then ease of operation is improved, but measurement precision deteriorates due to confusion between the two fluids
Solution Approach 1:
The patent employs a colorimetric detection method where the reagent strip changes color in the presence of urea from DEF contamination. The test solution transitions from yellow (negative) to green/blue (positive), providing a clear visual indicator that enables accurate differentiation between DEF and FSII even when stored in similar containers
Solution Approach 2:
The patent introduces an intermediary detection system consisting of the buffered urease solution and reagent strip that mediates between the fuel sample and the final detection result. The urease enzyme specifically catalyzes urea hydrolysis, and the subsequent pH change triggers the colorimetric reaction, creating a reliable intermediary detection mechanism
2Reliability
If a detection method is implemented to identify DEF contamination, then reliability is improved, but device complexity increases due to additional testing steps
Solution Approach 1:
The patent segments the detection process into distinct, manageable steps: (1) mixing fuel sample with buffered urease solution, (2) allowing enzymatic reaction to convert urea to ammonia, (3) adjusting pH to basic conditions, (4) adding reagent strip, and (5) observing color change. This segmentation makes the complex detection process systematic and easier to execute
Solution Approach 2:
The buffered urease solution performs self-service by automatically catalyzing the conversion of urea to ammonia without requiring external intervention. The enzymatic reaction occurs spontaneously under the buffered conditions, eliminating the need for complex equipment or skilled operators
3Measurement precision
If the detection process includes multiple steps for accurate detection, then measurement precision is improved, but loss of time increases due to extended testing duration
Solution Approach 1:
The patent applies preliminary action by pre-buffering the urease solution at optimal pH conditions before contact with the fuel sample. This preliminary preparation ensures that the enzymatic reaction proceeds rapidly and efficiently from the moment of mixing, reducing the overall detection time while maintaining precision
Solution Approach 2:
The patent utilizes parameter changes by adjusting the pH to basic conditions (pH 10-12) after the enzymatic reaction. This parameter change triggers the colorimetric reaction on the reagent strip, accelerating the detection process while ensuring accurate results through the specific pH-dependent chemical reaction
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
Effectively detects DEF contamination in fuel, preventing engine damage by identifying the presence of urea through a clear color change, ensuring accurate differentiation from other fuel additives.
Implementation Method 1
combining the fuel sample with a buffered urease solution to make a test solution; allowing the test solution to separate into layers and developing an aqueous layer to convert any urea from DEF, if present, into ammonia
Implementation Method 2
contacting a reagent strip with the aqueous layer; developing a color change of the aqueous layer to detect a presence of ammonia. The reagent strip may comprise solid bleach, an iron (III) cyano complex, such as, but not limited to a nitroprusside or ferricyanide salt, and salicylic acid
Implementation Method 3
adjusting a pH of the aqueous layer to greater than or equal to about 11; adding a pH adjustment solution to the test solution to adjust the pH of the aqueous layer to about 11
Data Source
AI summary
A method and kit for detecting the presence of diesel exhaust fluid in fuel is disclosed. The method includes obtaining a fuel sample, combining the fuel sample with a buffered urease solution to make a test solution, agitating the test solution, allowing the test solution to separate into layers and convert urea to ammonia. The method also includes adjusting a pH of the aqueous layer of the test solution, isolating the aqueous layer, immersing, agitating and then removing a reagent strip, and allowing the aqueous layer to develop a color change for an indication of presence of ammonia from any DEF contamination.