Joe Zibley-Analytical Problem:I-131 in Japanese Milk Supply
The recent disaster at the Fukushima Daiichhi nuclear power plant released many radionuclides into surrounding area. One of the main concerns after the evacuation of the area was radiation contamination of the area's food supply. Milk from Japan has shown higher levels of radioactive I-131 than is allowed by law. The FDA has even banned food products from Japan including milk. How can I-131 be detected in milk and the radiation levels quantified in as quick and accurate manner as possible? This is an important problem to solve because radiation levels for the public should always be kept as low as possible. More specifically I-131 can cause thyroid cancer especially in infants and young children. The central hypothesis is that I-131 in milk will have higher radiation levels closer to the nuclear plant. The analyte is I-131 in milk and the matrix is the milk and any contaminates in it.
Wakeford, Richard. And now, Fukushima. Journal of Radiological Protection [Online] 2011, 31, 167-176 http://iopscience.iop.org/0952-4746/31/2/E02/ (accessed Sept. 20, 2011)
Lubick, Naomi. Little Radioactive Material From Fukushima Reached Europe. Chemical and Engineering News [Online] 2011 http://pubs.acs.org/isubscribe/journals/cen/89/i34/html/8934scene.html (accessed Sept. 20, 2011)
UV Vis Absorption Spectrum
5b. I-131 won't absorb in UV-Vis spectrum but Iodide will react with starch, specifically amylose, to give a blue amylose-iodide complex. This method has been used but it seems that it is normally used to find the concentration of amylose as opposed to iodide. The iodide has a complex equilibrium with I(2) and I(3)- based on its concentration in the solvent. Ideally the equilibrium would be pushed all the way to 100% I(3)- because that is the species that forms a complex with amylose. This will not be a easy and straightforward way to find I concentration but it should work. Also I do not think this method will differentiate between I-131 and any other isotope so it would only really confirm the presence of Iodide in milk sample
1. dissolve amylose in 90% dimethyl sulfoxide and 10%water
2. isolate I-131 from milk samples
3. add I-131 and dilute to 10% dimthyl sulfoxide and blue amylose-iodide complex forms
maximum wavelength: 600nm with dimethyl sulfoxide
molar absorptivity: varies based on solvent concentration but mean value is 26,119(L/mol*cm)
Question 3 was originally searched for using CHEM 4101 library page. There weren't any promising papers and I wasn't expecting to find uv-vis info regarding I-131 so I modified search to looking for starch-iodide uv-vis information.
Knutson, C.A. A Simplified Colorimetric Procedure for Determination of Amylose in Maize Starch. Cereal Chemistry. 1985, 63, 89-92.
Similar Analytical Problems
a.Justin Michael- Boron in Groundwater
He is concerned with figuring out how to best remove boron from the environment using different sorbents to reach standard limits for drinking water. The analyte is boron, matrix is groundwater samples so likely very complex. Relevant because both are concerned with quantifying an element that is potentially harmful to people.
Osman Janshed- Detecting Prions
He is concerned with detection of prions in food before people eat them. The analyte is prions in a matrix of meat. It might be a little stretch to say they are similar but we discussed that we may have similar matrix with them both being food products.
b. Boron could have a similar study as I will need to do a study of I-131 concentrations based on distance. Boron may find this useful to see how groundwater treated in one place effects groundwater in nearby areas. Also for me studies might be useful to collect data on how cows are housed(inside/outside), food storage(inside/outside), milk processing(I-131 in large milk collection tanks, etc...). negative control for myself could be done in similar parts of Japan that have not been affected by Fukushima, any historical data of this sort for Japan.
c. My studies will probably not be similar to Osman's because our similarity is with the matrix. The studies listed above besides by distance will be unique to only my analytical problem.
Blog 6 Chemical Structures
I have not been able to find a definitive form of I-131 in milk but I know I2 is a stable and common form of Iodine. In studies quantifying iodine concentrations in milk they do not specifically say what from it is in. As far as detecting I-131 with a geiger meter the form of I-131 is irrelevant since no sample prep is needed for this type of detection.
Perkin Elmer sells radiochemicals including I-131. The catalog number for the most active sample is NEZ035A025MC which is 25mCi of NaI-131 in NaOH. The price isn't listed on the website.
Dahl, L;Opsahl, J; Meltzer, H; Julshamm, K. Iodine concentration in Norwegian milk and dairy products. British Journal of Nutrition 2003 90, 679-685