The Use of K42-tagged Erythrocytes in Blood Volume Determinations
5y/ml) is added with 10 ml KH2P04-NaOH buffer solution ( p H 7) and 5 ml CNBr solution, and heated in a water bath at 70'-80' C for 8 min, cooled in icecold water, and 5 ml 15% NaOH solution added. Calculation. Let a = content of nicotinamide in the sample for determination; b = content of nicotinamide in the sample of intermediate standard; c = amount of nicotinamide added to the sample for determination; f = dilution factor; and r =recovery (%) of the added nicotinamide throughout the
... oughout the operation. Then KH-4B is a carboxylic-type cation exchange resin prepared from phenoxyacetic acid and formaldehyde, and has a total capacity of 5.84 mEq/g dry resin. The same types of cation exchange resins, Amberlite IRC-50 (Rohm & Haas Co.) (4) and Wofatit C (I. G. Farbenindustrie Akt.-Ges.) ( 5 ) may be suitable for use in place of KH-4B. Amberlite IRA-400 is a strong-base-type anion exchange resin, and has a total capacity of 2.5 mEq/g dry resin. Since the chemical characteristics of Amberlite IRA-400 are analogous to those of sodium hydroxide, carbonate-free reagents and distilled water must be used for the treatment. Cationic impurities in an extract solution are adsorbed by the filtration through KH-4B-Na (sodium salt-type of KH-4B) at p H 5, but nicotinamide is not adsorbed by such an operation followed by the rinse with hot distilled water. Anionic impurities in an extract solution are adsorbed by filtration through Amberlite IRA-400-OH (hydroxide-type of Amberlite IRA-400) at p H 5, but nicotinamide is not adsorbed by such an operation followed by the rinse with distilled water. Nicotinamide contents of the pupae and eggs of various types of silkworm B. mori were determined by the method described above, and the analytical results shown in Table 1were obtained.