Considering increasing importance of analyzing seawater for129I, we developed a practical method for determination of129I in seawater using accelerator mass spectrometry by pre-treatment with solvent extraction. In this method, total inorganic iodine in 1 liter of seawater is extracted by hexane after iodate ions were reduced to iodide ions by ascorbic acid and iodide ions were oxidized by sodium nitrite. Recovery of total iodine was determined by ion chromatography. Accuracy and precision were examined by analyzing seawater samples of known concentrations and seawater added with the diluted NIST SRM 3230 Level I solutions. Repeatability of AMS measurement was checked using the seawater sample and AgI prepared from AgNO3and KI. As a result of analyzing seawater samples of known concentrations, accuracy and precision were found to be quite satisfactory. Overall repeatability of the analysis by the present method including pre-treatment was approximately 10% (R.S.D.) . It was concluded that129I concentration levels from 106to 107 atoms L-1or over in seawater can be determined by this method with sufficient accuracy and precision.
Perillae Herba, Sennae Folium, Cinnamomi Cortex, Phellodendri Cortex, Ginseng Radix, Glycyrrhizae Radix, Paeoniae Radix, and Zingiberis Rhizoma were irradiated with electron beam (5 MeV) and organic radicals were detected by ESR measurement, before and after irradiation (10 kGy) . A single line spectrum was detected at around g=2.005 in non-irradiated crude drugs, and radical concentrations were high in the leaf varieties of crude drugs. After irradiation, the signal intensity around g=2.005 increased, and a new subsignal was detected as a 3 mT shoulder of this signal. Broad, asymmetrically divided signals were also detected in irradiated root varieties of crude drugs. The free radical localized on the organic components of irradiated crude drugs tended to decrease with the water content. After irradiation, signal intensity reduced and reached a steady state after about 1 to 2 months. However, specificity of the ESR signal shape appearing after irradiation continued to be detectable for 6 months in leaf varieties and for a year in bark and root varieties of crude drugs. Consequently, it was concluded that ESR could be applied as an initial screening procedure to detect irradiated crude drugs.