Leaching Plastic Labware

Additives used to manufacture disposable plastic labware commonly used in life sciences laboratories can leach and interfere with biological assays, according to a report in Science (2008, 322, 917). A team led by pharmacology assistant professor Andrew Holt of the University of Alberta found that contaminants that end up in water and dimethyl sulfoxide (DMSO) used to rinse plastic tubes and pipette tips interfered with enzyme assays of human monoamine oxidase and with ligand-binding assays of rat γ-aminobutyric acid type A receptors. In most cases, the contaminants inhibited enzyme activity or ligand binding, but unidentified contaminants from wells in polystyrene or acrylic microtiter plates actually activated the enzyme. Using mass spectrometry, the researchers identified the biocide di(2-hydroxyethyl)methyldodecylammonium (DiHEMDA) and the plastic "slip agent" 9-octadecenamide (also known as oleamide) after rinsing plastic tubes with water or methanol. The authors suggest that these types of bioactive contaminants from plastic labware may be a common source of error in biological assays.