Creatine kinase isoenzyme MB: discrepancy between immuno-inhibition and electrophoretic measurement in lyophilized proficiency samples.

Then theircontentswere assayedfor vitamins E and A. Our results all agreed, within theerror of the methods, showing that neither Venojet nor Vacutainer Tube stoppers of the types available in South Africa contain dyes or antioxidants interfering with the assay of vitamin E, in agreement with the work of Sinclair and Slattery (1), or with the assay of vitamin A. Althoughthese results indicate that theparticular products we examined are suitable for use in the collection of blood forfluorometryofvitaminsA and E,we think that anyone undertaking fluorometric investigations would be well advised to test any rubber that comes into contact with their samples or, where practicable, to replace rubber with plastic, glass, or polystyrene.