Subject(s)
Hair/analysis , Mercury/analysis , Gamma Rays , Humans , Male , Neutron Activation Analysis , Spectrum AnalysisABSTRACT
Formation of the red complex between poly(vinyl acetate) and iodine in the presence of iodide is quantitatively independent of the method by which the polymer is prepared. In contrast, the amount of complex formed in the case of partly hydrolysed products of poly(vinyl acetate) depends strongly on the source of this polymer and may vary from sample to sample by as much as a factor of five, while the use of different hydrolysis methods gives rise to even greater differences in the amount of complex formed by the products. The determination of partly hydrolysed poly(vinyl acetate) through the red iodine complex is recommended only when the standard polymer sample and the unknown have been prepared in the same batch. Details of these systems are discussed.
Subject(s)
Erythrocyte Volume , Folic Acid/blood , Vitamin B 12/blood , Aged , Female , Humans , MaleABSTRACT
An accurate procedure for the determination of 1,2-diol groups in styrene glycol and poly-(vinyl alcohol) has been demonstrated. The diols are cloven with periodate and the excess of this is determined by means of standard arsenite solution.
ABSTRACT
A preliminary report of the use of methylphenidate and oxprenolo in 24 apathetic physically disabled elderly people is presented. The study was not psychometrically or statistically assessed but was judged by the ability to be discharged from hospital, achieved in 50% of cases, of patients who probably would require to remain in long-stay geriatric beds for the rest of their lives.
Subject(s)
Dementia/drug therapy , Drug Therapy, Combination , Methylphenidate/therapeutic use , Oxprenolol/therapeutic use , Aged , England , Female , Hospitalization , Humans , Long-Term Care , Male , Middle AgedABSTRACT
Polyvinyl acetate and iodine form a characteristic red complex in the presence of potassium iodide. Spectrophotometry of the complex at 510 nm in a methanol-water system at 20 degrees yields linear calibration curves over the range 25-100 mg of polyvinyl acetate per 1. of final solution. The limit of detection is 0.1 mg of polyvinyl acetate in 0.5 ml of initial sample. Replacement of acetate groups by inert groups reduces the sensitivity of the method, and other details of the system are discussed.
ABSTRACT
Polyvinyl alcohol (PVA), boric acid and tri-iodide form a characteristic blue complex. For a number of PVA samples, prescribed conditions were used to examine the precision of the formation and spectrophotometry of the complex. The precision of calibration curves was 1-2 % over the range 0-4 mg of PVA per 50 ml of final solution, over which Beer's law holds. Greater deviations can be caused by faulty preparation and aging of individual PVA solutions. The absorbance is independent of the content of residual acetate groups in the PVA for the range 0-15 %. The limit of detection is about 0.01 mg of PVA in 25 ml of sample. A pink colour in the system is due to association of iodine with acetate groups in the PVA. A blue or green colour is due to helical envelopment of iodine molecules by PVA chains stiffened by scattered cyclic groups. The mechanisms of these effects are discussed.
