Methods of isolating and detecting metal ions from proteins
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Publication Number
US-10859555-B2
Publication Date
2020-12-08
Expiration Date
Abstract
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.
Core Innovation
The disclosure provides a method of detecting a metal ion in a protein-containing sample by degrading proteins, separating resulting components, and measuring the metal ion in a prepared aqueous fraction. A proteinase K enzyme is added to a protein-containing sample to form an enzyme degradation product, concentrated nitric acid is then added to provide a mixture, and the mixture is filtered to provide a supernatant.
The supernatant is extracted with an organic solvent to remove organic solvent soluble byproducts to provide a washed aqueous layer. The metal ion is detected in the washed aqueous layer in a handheld GMR sensing device. The approach is described as applicable to heavy metal ions in protein-containing samples, including milk.
A related embodiment specifies detecting a heavy metal ion in a milk sample, including adding proteinase K to milk to form an enzyme degradation product, adding nitric acid to provide a de-emulsified mixture, filtering to provide a supernatant, and extracting the supernatant with chloroform to remove chloroform soluble byproducts to provide a washed aqueous layer. The heavy metal ion is then detected in the washed aqueous layer in a handheld GMR sensing device, with dependent variants specifying lead or uranium as the heavy metal ion.
Claims Coverage
The independent claims cover two core detection scenarios: detecting a metal ion in a protein-containing sample and detecting a heavy metal ion in a milk sample, each using a common workflow of proteinase K degradation, nitric acid treatment, filtration, organic solvent extraction, and detection in a handheld GMR sensing device. Across the independent claims, the inventive features are centered on preparing a washed aqueous layer suitable for handheld GMR detection and specifying key reagents and sample types.
Proteinase K enzyme degradation in a protein-containing sample
Adding a proteinase K enzyme to the protein-containing sample to form an enzyme degradation product.
Concentrated nitric acid treatment and supernatant preparation
Adding concentrated nitric acid to the enzyme degradation product to provide a mixture; filtering the mixture to provide a supernatant.
Organic solvent extraction to provide a washed aqueous layer
Extracting the supernatant with an organic solvent to remove organic solvent soluble byproducts to provide a washed aqueous layer.
Handheld GMR detection of the metal ion
Detecting the metal ion in the washed aqueous layer in a handheld GMR sensing device.
Proteinase K degradation in a milk sample
Adding a proteinase K enzyme to the milk sample to form an enzyme degradation product.
Nitric acid de-emulsification and supernatant preparation in milk
Adding nitric acid to the enzyme degradation product to provide a de-emulsified mixture; filtering the de-emulsified mixture to provide a supernatant.
Chloroform extraction to provide a washed aqueous layer
Extracting the supernatant with chloroform to remove chloroform soluble byproducts to provide a washed aqueous layer.
Handheld GMR detection of the heavy metal ion in milk
Detecting the heavy metal ion in the washed aqueous layer in a handheld GMR sensing device.
Overall, the claim set protects detection in handheld GMR sensing by coupling proteinase K protein degradation with nitric-acid treatment, filtration to form a supernatant, and organic solvent extraction to yield a washed aqueous layer where the metal or heavy metal ion is detected. Dependent claims further constrain the sample type, introduce an optional denaturing agent, constrain filtering by pore size range, and narrow the heavy metal species to lead or uranium.
Stated Advantages
Enables detection of a metal ion in a protein-containing sample using a handheld GMR sensing device.
Provides detection for heavy metal ions in a milk sample using a handheld GMR sensing device.
Documented Applications
Detecting a metal ion in a protein-containing sample using protein degradation and handheld GMR sensing.
Detecting a heavy metal ion in a milk sample, including detection of lead and detection of uranium.
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