Metal Ion Detection in Milk via Enzymatic Protein Degradation
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Solution Overview
Problem
Existing technologies for detecting metal ions, particularly heavy metals in complex protein-containing substrates like milk, are expensive, time-consuming, and require specialized laboratory equipment, making field detection impractical due to interference from milk's complex matrix.
Innovation Solution
A method involving the addition of a protein-degrading enzyme, such as proteinase K, followed by acid treatment and filtration with a nitrocellulose filter, and extraction with an organic solvent to isolate metal ions, allowing for their detection in a protein-containing sample, including milk, using bioassays like fluorescence or GMR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing metal detection technologies are used, then detection capability is provided, but cost, time consumption, and device complexity increase significantly
Solution Approach 1:
The patent extracts and removes proteins from the milk sample using proteinase K enzyme digestion and phenol-chloroform extraction, separating the metal ion detection step from the complex protein matrix. This extraction principle enables the use of simpler detection devices by eliminating the interfering protein components that would otherwise require complex specialized equipment.
Solution Approach 2:
The patent performs preliminary protein degradation and sample preparation steps before metal ion detection. By pre-treating the milk sample with proteinase K and performing extraction procedures in advance, the complex matrix is simplified beforehand, allowing subsequent detection to be performed with less complex and more portable equipment.
2Measurement precision
If biomolecule-based assays are used for metal detection, then detection sensitivity is achieved, but sample preparation time increases due to matrix interference
Solution Approach 1:
The patent extracts proteins from the milk matrix using phenol-chloroform extraction, removing the interfering biomolecules that cause matrix interference. This extraction step maintains detection sensitivity by preserving metal ions in the aqueous phase while eliminating proteins that would otherwise extend preparation time through repeated washing and purification steps.
Solution Approach 2:
The patent changes the chemical parameters of the sample by adjusting pH and using chemical reagents like phenol and chloroform to alter the solubility and distribution of proteins and metal ions. This parameter change enables rapid separation of proteins from metal ions, reducing sample preparation time while maintaining assay sensitivity.
3Ease of operation
If field detection devices are used, then portability is improved, but detection accuracy decreases due to milk matrix interference
Solution Approach 1:
The patent performs preliminary protein removal and sample simplification steps that can be completed in the field using portable equipment. By pre-treating the milk sample with proteinase K and performing extraction procedures before detection, the accuracy required for field detection is achieved without sacrificing portability.
Solution Approach 2:
The patent extracts and removes interfering proteins from the milk matrix using phenol-chloroform extraction, creating a simplified sample suitable for accurate detection with portable field devices. This extraction principle eliminates the matrix interference that would otherwise reduce detection accuracy in field settings.
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 rapid, cost-effective detection of metal ions in milk and other protein-rich samples, reducing detection time to about 45-60 minutes and avoiding the need for specialized equipment, while maintaining sensitivity and specificity for heavy metals like lead and uranium.
Implementation Method 1
adding a protein degrading enzyme to the protein-containing sample to form an enzyme degradation product
Implementation Method 2
adding nitric acid to the enzyme degradation product to provide a de-emulsified mixture
Implementation Method 3
extracting the supernatant with chloroform to remove chloroform soluble byproducts
Implementation Method 4
filtering the de-emulsified mixture to provide a supernatant
Data Source
AI summary
A method of detecting a metal ion in a protein-containing sample includes adding a protein degrading enzyme to the protein-containing sample to form an enzyme degradation product, adding an acid to the enzyme degradation product to provide a mixture, filtering the mixture to provide a supernatant, extracting the supernatant with an organic solvent to remove organic solvent soluble byproducts to provide a washed aqueous layer, and detecting the metal ion in the washed aqueous layer. The method is amenable to the detection of heavy metal ions in complex products such as milk. A kit includes reagents for performing the method.