Chemistry: analytical and immunological testing – Nitrogen containing – Amine and quaternary ammonium
Reexamination Certificate
2000-03-03
2001-10-16
Warden, Jill (Department: 1743)
Chemistry: analytical and immunological testing
Nitrogen containing
Amine and quaternary ammonium
C436S110000, C436S056000, C436S092000
Reexamination Certificate
active
06303384
ABSTRACT:
AREA OF THE INVENTION
This invention relates to a reagent and use of that reagent for detecting adulterants in aqueous samples, particularly in biological specimens such as urine samples.
BACKGROUND OF THE INVENTION
Adulteration of urine specimens has become an increasingly significant issue in urine drug testing. Products to mask the presence of drugs in the testing process are readily available and new products continue to emerge to stay in the forefront of technology. This invention provides a reagent that can be used in initial testing to screen for the presence of multiple adulterants. The ability of the reagent to detect multiple adulterants is significant because of the limited number of available reagent channels on the instruments used for analysis. This invention provides a reagent and method for detecting in a single, stable, test the presence or absence of three common adulterants: nitrites, pyridinium chlorochromate and hypochlorites like common bleach.
SUMMARY OF THE INVENTION
In a first aspect this invention relates to a colorometric method using a diazo dye precursor for distinguishing between the presence of a nitrite ion and a chlorine-containing oxidizing agent in an aqueous solution, which method comprises adding to an aqueous solution a diazo dye precursor and an agent which stabilizes the colored intermediate formed by the reaction of the nitrite ion with the diazo dye precursor, reading and recording the absorbance of the solution at the peak corresponding to said intermediate formed by the nitrite/diazo dye precursor reaction and the peak corresponding to the color generated by the reaction of the chlorine-containing oxidizing agent and the diazo dye precursor, and subtracting the absorbance of the peak corresponding to the chlorine adulterant from the absorbance of the peak corresponding to the intermediate formed by the nitrite/diazo dye precursor reaction, the readings being taken from a single container or optionally from two different containers.
In a second aspect, this invention relates to an improved colorometric assay for detecting and distinguishing simultaneously in a single pot containing an aqueous solution the presence of a nitrite ion and a halogen-containing oxidizing agent using a diazo dye precursor wherein the improvement comprises using between about 0.1 and 10% weight/volume of a nucleophilic compound as the stabilizing agent for stabilizing the colored intermediate formed by the reaction of the diazo dye precursor and the nitrite ion wherein the stabilized the intermediate is stabilized for at least about 1 minute or more.
In a third aspect this invention relates to a reagent for detecting simultaneously in an aqueous sample the presence of nitrites and chlorine-containing oxidizing agents wherein the reagent comprises a diazo dye precursor and a nucleophile stabilizing agent.
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Mills Susan P.
Novinski John A.
Schaffer Michael I.
Gakh Yelena
Quest Diagnostics Investments Inc.
Stout Donald E.
Stout, Uxa Buyan & Mullins, LLP
Warden Jill
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