Test article interference

CS(n) Calibration standards TIC Test article interference check... 

In order to cope with the problem of drug Induced modifications of laboratory test values, laboratory scientists should possess an understanding of the mechanisms Involved In these Interferences. The purpose of this article Is to consider these mechanisms and discuss the role of the computerized drug-test Interference file In assisting In the prediction as well as Interpretation of apparent test results. 

Third, for each substance (or article) that is mixed with a carrier (solvent or other medium) 1) the uniformity or concentration shall be determined, 2) the solubility shall be determined (EPA only), and 3) the stability in the mixture shall be determined. Expiration dates shall be clearly shown and (EPA only) the device used to formulate the mixture shall not interfere with the integrity of the test. 

In addition to the need to monitor known problematic compounds, newer compounds are being identified as potential threats to humans and as such need to be monitored in the atmosphere. For example, researchers reported (10) that several chemical and instrumental analyses of HPLC fractions provided evidence for the presence of /V-nitroso compounds in extracts of airborne particles in New York City. The levels of these compounds were found to be approximately equivalent to the total concentrations of polycyclic aromatic hydrocarbons in the air. Since 90% of the N-nitroso compounds that have been tested are carcinogens (10), the newly discovered but untested materials may represent a significant environmental hazard. The procedure involved collecting samples of breathable, particulate matter from the air in New York City. -These samples were extracted with dichloro-methane. Potential interferences were-removed by sequential extractions with 0.2 N NaOH (removal of acids, phenols, nitrates, and nitrites) and 0.2 N H2S04 (removal of amines and bases). The samples were then subjected to a fractional distillation and other treatments. Readers interested in the total details should consult the original article (10). Both thin-layer chromatography (TLC) and HPLC were used to separate the compounds present in the methanolic extract. 

Analysis of Antimony Ore (the following is an abstract from Thos. Brown, Jr. s, article on the determination of antimony in ores, in the Jowm. of Am. Chem. Soc., Sept. 1899).—Impurities such as silica, iron, and lime would not materially interfere with the schemes of analysis used. Lead, mercury, copper, tin, and arsenic, when found in quantities larger than traces, should be separated from the antimony when its determination is by the method of sulphides also tin and arsenic when the oxide method is used. A preliminary qualitative test should always be made for the... 

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