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Publication Number
US-8715952-B2
Publication Date
2014-05-06
Expiration Date
Abstract
In general, the present invention provides a reliable assay for the quantitative determination of p-aminophenol in an aqueous sample. More particularly, the present invention provides a rapid enzyme-based assay for the quantitative determination of acetaminophen in a sample. The assay employs a xylenol chromophore and a catalyst that is preferably a weak oxidizer. The assay provides reliable results in the presence or absence of N-acetylcystiene (NAC) and can therefore be used to monitor acetaminophen levels during NAC treatment. Methods and kits for determining acetaminophen concentration in an aqueous sample are also provided.
Core Innovation
The invention describes an enzyme-based assay for determining acetaminophen concentration in an aqueous sample. Acetaminophen is converted to p-aminophenol, which is oxidatively coupled with a xylenol chromophore in the presence of a suitable catalyst to form a colored product. The amount of colored product is proportional to the acetaminophen present, and the method is stated to be reliable with or without therapeutic levels of NAC.
The patent summary reports that the xylenol system, preferably 2,5-dimethylphenol, produces similar absorbance spectra with and without NAC and has reduced bilirubin interference; measurement near 660 nm is also reported to reduce bilirubin and hemoglobin interference. The provided partial content does not include the background section, so the problem stated there is not explicitly described.
Claims Coverage
The relevant claims contain three independent claims: two directed to determining acetaminophen concentration and one directed to determining p-aminophenol concentration.
Acetaminophen determination using a xylenol chromophore
The method determines acetaminophen concentration in an aqueous sample through conversion to p-aminophenol and formation of a colored product with a xylenol chromophore and a suitable catalyst. The amount of colored product is proportional to the acetaminophen present, and the method is stated to be reliable with or without therapeutic levels of NAC.
Two-reagent acetaminophen assay
The assay uses a first reagent comprising aryl acylamidase and a second reagent comprising a xylenol chromophore to produce a colored product from acetaminophen in an aqueous sample. The amount of colored product is proportional to the acetaminophen present, and the assay is stated to be reliable with or without therapeutic levels of NAC.
P-aminophenol determination using a weak oxidizer
The method determines p-aminophenol concentration in an aqueous sample by forming a colored product with a xylenol chromophore selected from 2,5-dimethylphenol, 2,6-dimethylphenol, and 2,3-dimethylphenol, using a weak oxidizer as the catalyst. The amount of colored product is proportional to the p-aminophenol initially present.
The independent claims cover acetaminophen measurement using a xylenol-based colored product, a two-reagent assay format, and p-aminophenol measurement using specified xylenol chromophores with a weak-oxidizer catalyst.
Stated Advantages
The acetaminophen method and assay are stated to be reliable in the presence or absence of therapeutic levels of NAC.
The xylenol system is reported to have reduced NAC interference compared with the 8-hydroxyquinoline assay.
The assay is reported to have improved resistance to bilirubin interference, and measurement near 660 nm is reported to reduce bilirubin and hemoglobin interference.
Experimental results report accurate recovery across tested acetaminophen concentrations in the presence of NAC.
Documented Applications
Determining acetaminophen concentration in aqueous samples, including blood, serum, or plasma.
Determining p-aminophenol concentration in an aqueous sample.
Automated two-reagent acetaminophen testing and diagnostic kits for the assay.
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