The biosynthesis and metabolism of polyols. 2. The metabolism of 14C-labelled d-glucose, d-glucuronic acid and d-glucitol (sorbitol) by plum leaves

0 5 mg.) obtained by evaporating portions (usually 5- lOO,ul.) to dryness on nickel planchets.Radioactivity was determined either in a counter with a thin end-window Geiger tube, or in a windowless flowcounter (Type SC-16G; Tracerlab, Waltham, Mass., U.S.A.).In both cases the apparatus was calibrated for counting Ba14C03 disks by determining the count rate of 'infinitely thick' Ba14CO3 disks prepared from compounds of known specific activity, and for counting thin films with weighed portions (2-12 ,ul.) of an aqueous solution contain- ing known amounts of D-[6-14C]glucose (specific activity, 42 ,uc/mg.).The performance of the counters was frequently checked with a disk of poly([14C]methyl methacrylate) as a standard reference source.