View Report Details

Measurement of 129I in fruit

Project Code: R01011

30/06/2004

Westlakes Scientific Consulting
McDonald, P

Attempts were made to measure the ¹²⁹I-content of samples containing iodide solution and AgI powder using AMS. Sample preparation was conducted at Central Science Laboratories (CSL) and ¹²⁹I analysis was conducted at Xceleron Ltd using Accelerator Mass Spectrometry. Attempts at analysis however, were unsuccessful. The ¹²⁹I/¹²⁷I ratio in the standards provided, ranged from 10^-6 to 10^-12. Difficulties were encountered in detecting the more abundantly present stable ¹²⁷I. Hence the prospect of detecting the much lower levels of ¹²⁹I could not be considered until problems in detecting ¹²⁷I could be resolved. Such problems have not been overcome.

The information produced by CSL indicated that there was approximately 1.5 μg of ¹²⁷I in 100 mg of carrier material such as NaCl. The injector magnet was set up to examine ¹²⁷I from the cathode containing AgI powder and then, without any adjustment, the ¹²⁷I output from a range of cathodes was checked. None of the cathodes with CSL-produced material gave a beam current of more than 45 nA (typical beam current should be of the order of 1 μA). Therefore, samples prepared using the method of acid-base digestion did not contain sufficient ¹²⁷I to be analytically useful.

The method used in isolating iodine in the standard solution was UKAS accredited. However, the first step in the analytical process, of extracting iodine efficiently from the
standard/sample, could not be performed satisfactorily for AMS analysis, despite three attempts being made. Therefore the chemistry of iodine extraction from standards/samples
needs to be better understood.

From the experience gained in producing this report, it is recommended that the two-phase approach, as described in Section 2, be adopted for any future work on the analysis of ¹²⁹I in fruit using AMS.

Main File

Some of the files on this site may be in a format that your computer can't read. However, you can download Readers and Viewers for the following document types below: