Submitted to: Analytical Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 12, 1996
Publication Date: N/A
Interpretive Summary: The development and use of molecular imprints, sometimes called "plastic antibodies", is an emerging technology in which plastic impressions of a molecule are made. This is done by forming plastic polymers around the molecule and then extracting the molecule away from the newly formed polymer. Once these plastic impressions are made, they are ground to a fine powder and can be used in a variety of applications. Recently, we made a molecular imprint for the herbicide atrazine, one of the most widely used agrochemicals in the world. In this paper, we describe the use of molecular imprints as tools for extracting trace levels of atrazine from beef liver tissue so it can be measured. Liver tissue is very complex and cleanup of the sample is necessary prior to analyzing. To do this, the molecular imprints were used to selectively remove atrazine from the sample. The atrazine was then rinsed off the imprint and measured. The use of the imprints greatly improved the analysis. This is the first report of the use of molecular imprints for this purpose. It should be a very valuable technique for simplifying extraction and measurement of residue levels in foods and environmental samples.
Molecular imprinting technology has many potential applications in residue analysis. This technique involves the synthesis of polymers in the presence of an imprint molecule. After extracting the imprint molecule, the polymer can then be used as a specific binding matrix for the imprint molecule or structurally-related compounds. We have investigated the use of molecularly-imprinted polymers as solid phase matrices for the extraction and cleanup of biological sample extracts. An anti-atrazine polymer was used to clean up organic extracts of beef liver. These and unpurified extracts were analyzed by both reversed-phase HPLC and ELISA. The use of molecularly-imprinted solid phase extraction (MISPE) improved the accuracy and precision of both methods, and lowered the limit of detection for the HPLC method (0.005 ppm). Atrazine recovery as determined by HPLC from beef liver homogenates spiked to levels from 0.02 to 0.5 ppm averaged 80.0% following MISPE and 51.5% for the unpurified extracts. Atrazine recovery as determined by ELISA averaged 85.2% following MISPE and 67.5% for the unpurified extracts. Crude tissue sample extracts greatly interfered with both the HPLC and ELISA methods. However, the use of MISPE allowed for the rapid analysis of complex biological matrices using either method at the tolerance level of 0.02 ppm in meat products. The application of molecular imprinting technology for solid phase extraction is a new approach for the analysis of highly lipophilic low molecular weight contaminants.