The electrophoresis of226Ra and it's decayed nuclides was carried out by using hydrochloric acid in the positive electrode cell and aqueous solution of potassium fluoride in the negative electrode cell. Experimental factors, i.e. concentrations of potassium fluoride and hydrochloric acid, intensity of electric field, duration for electrophoresis and pH value of the potassium fluoride solution etc. were examined. The sample solution was of 0.01 M hydrochloric acid with a tracer amount of226Ra and210Pb. Each of these nuclides was carrier free and was 4GBq/l (1μCi/ml) in concentration. For the sake of autoradiography, a potoengraving film (Fujilith Ortho Film, TAC=135) was made use of examining the locations of the separated radioactive bands obtained on the paper strip. Their 9 and r radioactivities were detected as the film darkening on developing the film. According to the positions thus detected, the strip filter paper was cut into pieces and the species of radionuclides were determined by the measurements of energies and half-lives on fi and r rays. The locations of the separated a-radionuclides were decided by etching the surface of it's film with 6 M aqueous solution of sodium hydroxide and the species of radio. nuclides were determined by the solid state a-track detection method. As the result, the optimum conditions for the separation are to use 0.01 M hydrochloric acid in the positive cell and 0.005 M potassium fluoride of pH 6.2 in the negative cell, intensity of the applied electric field being 1000 V/30 cm, and electrophoresis time being 20 minutes. The proposed method gave good results for focusing and separating the radium series nuclides. Bands of210Bi and210Po were found on the positive electrode side, while the bands of226Ra and210Pb (containing214Pb) were on the negative electrode side.
A convenient method for the determination of trace amounts of137Cs in agricultural and livestock products was studied by use of a low back-ground β-ray spectrometer. Simplification, rapidi fication and accuracy in the determination of trace amounts of137Cs in environmental samples were aimed at and designed. The β-ray spectra, which were measured by the low back-ground β-ray spectrometer on the counting sample after chemical separation (AMP-H2PtCl6method), were analyzed by means of the weighted least squares method using an automatic analyzer, and then radioactivities of40K, 87Rb and137Cs were determined. The results obtained by this method were in good agreement with the results obtained by conventional method using a low back-ground GM counter after chemical separation (AMP-Bio-Rex·40-H2PtCl6method) in the determination of137Cs, and then applicability for environmental samples was studied. The radioactivity of137Cs only could be determined by this method without using Bio-Rex·40 cation exchange resin to remove impurities such as40K and87Rb.
In order to improve goodness-of-fit in RIA standard analysis, programs for computing loglogistic and cubic log-logit were written in BASIC using personal computer P-6060 (Olivetti) . Iterative least square method of Taylor series was applied for non-linear estimation of logistic and log-logistic. Here“log-logistic” represents Y= (a-d) / (1+ (log (X) /c) b) +d As weights either 1, 1/var (Y) or 1/σ2 were used in logistic or log-logistic and either Y2 (1-Y) 2, Y2 (1-Y) 2/var (Y), or Y2 (1-Y) 2/σ2 were used in quadratic or cubic log-logit. The term var (Y) represents squares of pure error and σ2 represents estimated variance calculated using a following equation log (σ2+1) =log (A) +J log (y) . As indicators for goodness-of-fit, MSL/Se2, CMD% and WRV (see text) were used. Better regression was obtained in case of alpha fetoprotein by log-logistic than by logistic. Cortisol standard curve was much better fitted with cubic log-logit than quadratic log-logit. Predicted precision of AFP standard curve was below 5% in log-logistic in stead of 8% in logistic analysis. Predicted precision obtained using cubic log-logit was about five times lower than that with quadratic log-logit. Importance of selecting good models in RIA data processing was stressed in conjunction with intrinsic precision of radioimmunoassay system indicated by predicted precision.
The characteristics of the motion corrector system attached to LFOV γ-camera (Searle) was evaluated using a T-shaped plane source and point sources. The random movement without rotation of a T-shaped plane source was successfully corrected. However, rotating motion of the plane source was not corrected. When a point source placed on a rotating table, ring images were obtained. When motion corrector was used, the radius of ring images was increased with the increase of rotating speed and it was decreased with the increase of radioactivity of the source. Line images were obtained when point sources were placed on a shaker, which caused linear periodic motion of the sources. The use of the motion corrector reduced the length of line images.