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The Chemical Educator

ISSN: 1430-4171 (electronic version)

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Abstract Volume 12 Issue 6 (2007) pp 399-401

An Immunoassay for Drug Screening in the Forensic Laboratory

Rebecca E. Barlag

Department of Chemistry and Biochemistry, Ohio University, Clippinger Laboratories, Athens, Ohio 45701,
Received May 17, 2007. Accepted August 11, 2007.

Published online: 15 October 2007

Abstract. In forensic toxicology, immunoassays are the key sample-screening techniques for drugs in human fluids. Samples that show positive results using immunoassays are presumptive specimens; therefore, the presence of the drug must be confirmed by an alternative analytical technique. The purpose of this laboratory procedure is to introduce the fundamentals of the enzyme multiplication immunoassay technique, EMIT, to undergraduates in a forensic laboratory and lead the laboratory class into a discussion and application of analytical instrumentation for confirmatory analyses. The EMIT technique is based on a colorimetric reaction, the product of which can be measured spectrophotometrically. In this experiment, students used commercially available kits containing calibration standards to construct a calibration curve of the drug theophylline. A solution containing an unknown amount of theophylline in synthetic urine was then analyzed and compared to the calibration curve to determine if the concentration of theophylline is within the therapeutic range, 10 to 20μg/mL. Ninety percent of students in this particular class were able to accurately determine the concentration of theophylline in the unknown sample.

Key Words: Laboratories and Demonstrations; organic chemistry; synthesis; NMR

(*) Corresponding author. (E-mail:

Article in PDF format (133 KB) HTML format

Supporting Materials:

An Excel spreadsheet template and instructions on data manipulation are provided to the students. Post-laboratory questions that encourage critical thought and comparisons to other techniques are also provided, including reasonable answers to each (169 KB).

Issue date: December 1, 2007

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