In Japan, the presence of tin in refreshing beverages is permitted at the concentration of not exceeding 150ppm. Fruit juices and fruits in lacquer-lined cans generally contain tin ranging from 10ppm to 50ppm. In these cases, a colorimetric method is preferable to a gravimetric method for the determination of tin content. Phenylfluorone is generally used as a reagent to determine tin colorimetrically, but, according to the conventional colorimetric method, tin is determined in the presence of this excessive reagent and the absorbance of the test solution shows usually 0.15-0.25 at about 510mμ. The authors have improved the sensitivity and precision of this method by making tin in the test solution react with phenylfluorone, extracting the excess of phenylfluorone with chloroform, and reducing the absorbance of blank solution below to 0.1.
Previous report (Aiso et al, 1962) dealt with macroscopic examination of rats fed 2- (2-furyl) -3- (5-nitro-2-furyl) acryl amide and nitrofurazone. In the present study we have observed their liver, kindney, heart, spleen and testis histologically. Degenerative changes, atrophy, hydropic degeneration, pyknosis, and fatty metamorphosis of the hepatic cells, were observed in all groups of the rats fed nitrofurazone, but the extend of disorders was mild in general, and the degree of changes was more intensive when the rate of chemical concentration in the diet was increased. Cirrhotic changes were not recognized. On th contrary, the tendency of hypertrophy of the hepatic cells was noted in the rats fed 2- (2-furyl) -3- (5-nitro-2-furyl) acryl amide, especially at the 0.02% and 0.2% level. Degenerative changes were markedly observed in only a group of rats fed the diet at the level of 0.2% for one year, and their growth was retarded. Cirrhotic changes were also not recognized. There was nothing of the neoplastic changes in hepatic cells of all the rats fed both derivatives. Remarkable toxic effect in the kidney, heart, spleen and testis was not observed in all groups fed both compounds.
The action of enzymes such as diastase, takadiastase, pancreatin, amylase of Bacillus subutilis, cellulase and saliva, on carboxymethylcellulose (CMC), carboxymethylstarch (CMS), and methylcellulose (MC), was studied concerning the production of reducing sugar and the change of the viscosity of each 1% aqueous solution. Cellulase produced some reducing sugar from CMC and reduced the viscosity of CMC aqueous solution, and takadiastase followed it. Pancreatin, amylase of B. subtilis and saliva produced little or no reducing sugar from CMC, but these enzymes produced reducing sugar from CMS and reduced the viscosity of CMS aqueous solution. MC was affected slightly by cellulose but other enzymes gave no influence on MC.