| Summary: | Santowhite, a commercial antioxidant used in the manufacture of polypropylene, contaminates 12-ml polyallomer tubes to the extent of 0.2–0.3 mg/tube. It is distributed through the plastic and appears as a microscopic dust on the tubes' surfaces. In the preparation of polysomes from rat liver by standard methods, approximately 15% of the antioxidant in previously water-washed tubes was removed by suspension of the polysome pellet with stirring in 1–2 ml of Tris buffer, pH 7.8. The polyallomer impurity has been shown to be identical with Santowhite, which is 4,4′-butylidene-bis(6-tert-butyl-m-cresol), by UV, mass, and NMR spectra. It is not uniformly removed from polyallomer tubes by common detergents but is removed by washing with acetone, to which the plastic is resistant.
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