Usefulness of gas chromatograph-mass spectrometer-computer system (GC-MS-CPU) not only for measurement of specific activities of14C-labelled compounds in a mixture but also for evaluation of14C-labelled compounds in terms of examining their purities and elucidating chemical structures of the impurities was proved. A sample of methyl 2- (p-chlorophenyl-14Cn) -3-methylbutylate (III) synthesized from p-chlorophenyl-14Cn-acetonitrile (VI) was analyzed by GC-MS-CPU, and it was found that the labelled compound was contaminated with a small amount of the corresponding m-isomer (IV) having a very high specific activity. Further examination suggested that the contaminating misomer (IV) originated from m-chlorophenyl-14Cn-acetonitrile (IX) which had already contaminated in the starting material (VI), and also that cyanomethylation of p-dichlorobenzene-14Cn (VIII) by benzene-type reaction resulted in producing a mixture of p- and m-chlorophenyl-14Cn-acetonitriles (VI, IX) .
In order to study the metabolic fate of alacepril, an anti-hypertensive agent, the14C-labeled compound of alacepril and its related compounds were synthesized. [Prolyl-U-14C] alacepril was synthesized in over-all yield of 32.7-38. 0% by the mixed anhydride condensation of L phenylalanine with [prolyl-U-14C] DU-1163, which had been prepared from L- [U-14C] proline and N (S 3-acetylthio-2-methylpropanoyloxy) succinimide. [Prolyl-U-14C] captopril and [prolyl-U-14C] DU-1227 were prepared in high yields by hydrolysis of [prolyl-U-14C] DU-1163 and [prolyl-U-14C] alacepril, respectively. [Prolyl-U-14C] captorilcysteine was synthesized by condensation of [prolyl-U-14C] captopril with cystine S-monoxide in 55.0% yield.
The purpose of this study is to evaluate the clinical efficacy of liver SPECT (single photon emission computed tomography) . Eleven hospitals which are in or near Tokyo are participating in this study. Planar liver images and SPECT images of 134 cases which were retrospectively confirmed for its final diagnosis were collected. At the first study, the planar images (PS) were read by 13 nuclear medicine physicians. The second, the image reading by the combination of the planar images and the SPECT images (PS+SPECT) were performed. The confidence level of diagnosis for SQL (space occupying lesion) obtained by the image reading of PS and PS+SPECT has been analyzed by using the SOL detection model. The SQL detectability of PS+SPECT was higher than that of PS only. However, these differences were not statistically significant.
A radiochemical displacement method for the determination of micro amounts of Hg (II) has been developed. 65Zn was displaced from the Zn-1- (2 pyridylazo-2-naphthol) complex at pH 5 in borate buffers by Hg (II) . 10-80 μg of mercury could be determined. Interference of various metal ions and methods for suppression have also been carried out.
Iodine-131 concentrations in thyroid glands of cows, oxen and swine carried in the Yokohama slauterhouse were measured. The γ-ray spectral analysis was done with a Ge (Li) detecter. It is considered that131I in thyroid glands of domestic animals resulted from Chinese open-air nuclear tests and radioactive materials used at medical facilities. It is presumed that131I from medical facilities was taken in swine thyroid glands from the leavings of meals of patients.