Iodine Contamination

The concentrations of chlorine, bromine, and iodine of meteorites measured by Goles et al. (1967) raised the suspicion that non-Antarctic meteorites in museums had been contaminated by being handled with bare hands by collectors and because they had been stored for years in display cases through which air could circulate freely. Therefore, Dreibus and Wanke (1983) and Dreibus et al. (1986) measured the concentrations of halogens in Antarctic meteorites in order to document the contamination of non-Antarctic meteorites. The results in Table 18.7 danonstrated that Antarctic meteorites actually have unexpectedly higher concentrations of fluorine, chlorine, and iodine than similar meteorites of non-Antarctic origin. Even Antarctic martian meteorites have higher iodine concentrations than non-Antarctic meteorites from Mars. 

The apparent enrichment of Antarctic meteorites in iodine and, to a lesser extent, in chlorine is expressed in Table 18.7 by the Antarctic/non-Antarctic ratios of all four elements. The iodine ratios range from 25 in shergottites, to 46 in eucrites, and to 120 in howardites. Even Antarctic carbonaceous chondrites and ordinary chondrites (H) are enriched in iodine by factors of 24 and 2.5, respectively (not shown). These results demonstrate that the Antarctic meteorites are not pure and pristine as expected, but have been extensively contaminated by iodine and, to a lesser extent, by fluorine and chlorine. 

These insights indicate that the presence of excess iodine, chlorine, fluorine and, to a lesser extent, bromine, on the surfaces of Antarctic stony meteorites is attributable to the deposition of aerosol particles (Cl, F, Br) and of methyl iodide from the atmosphere. In other words, the excess halogens on the surfaces of Antarctic meteorites are atmospheric contaminants rather than weathering products. Accordingly, the amount of excess iodine on a meteorite lying on an Antarctic ice field increases primarily as a function of time and is less dependent on the climatic conditions on the ice field and on its distance from the coast. 

Langenauer and Krahenbiihl (1993) subsequently analyzed sequentially-removed surface layers of ordinary chondrites from four different locations along the Transantarctic Mountains in order to relate the extent of their contamination to their location on the ice fields of the Allan HiUs, the Elephant Moraine, the Lewis Cliff ice tongue, and the Thiel Mountains. Their analytical data confirmed that the concentrations of iodine and of all other halogens decrease with depth below the surfaces of ordinary chondrites. The depth profile of iodine in ALHA 77258 (H6 terrestrial age (270 70) x 10 years Score and Lindstrom 1990 Nishiizumi et al. 1989) in Fig. 18.20 shows that the iodine concentration 

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Hydrogen iodide (anhydrous) [10034-85-2] M 127.9, b -35.5°. After removal of free iodine from aqueous HI, the solution is frozen, then covered with P2O5 and allowed to melt under vacuum. The gas evolved is dried by passage through P2O5 on glass wool. It can be freed from iodine contamination by repeated fractional distillation at low temperatures. Fumes in moist air. HARMFUL VAPOURS. 

Historically, the rhodium catalyzed carbonylation of methanol to acetic acid required large quantities of methyl iodide co-catalyst (1) and the related hydrocarboxylation of olefins required the presence of an alkyl iodide or hydrogen iodide (2). Unfortunately, the alkyl halides pose several significant difficulties since they are highly toxic, lead to iodine contamination of the final product, are highly corrosive, and are expensive to purchase and handle. Attempts to eliminate alkyl halides or their precursors have proven futile to date (1). 

Phthalocyanines are organic semiconductors that strongly absorb visible light, and have been extensively investigated for use in photovoltaic (11), and photoelectrochemical cells (12.). The results however were somewhat inconsistent, and this was probably due to the presence of impurities which were not always clearly identified. Commercially available phthalocyanine was analyzed in order to determine the trace elements present, as well as the effect of heat treatment on the iodine contamination. The X-ray spectra, for an accumulated charge of 15 (1C, from untreated and from H2PC purified for... 

High, Si steel fabrication issues Coated materials (Pt) cost issue Ceramics promising, but have fabrication and joining issues Dry wall boiler design with ceramics may be option Data needed with iodine contamination Incoloy 800HT may address intergranular corrosion C—SiC composites should be examined... 

Mercury manometers should be isolated during this procedure. Iodine (1.3100 g, 5.16 mmole) is resublimed into a 10-mL ampule which is attached to the vacuum system and thoroughly evacuated. (Occasional cooling with a bath at -78° and the use of the glass wool above the ampule will minimize iodine contamination.) The ampule is cooled to -196° and dimethylgermane (about 6.0 mmole) is condensed into it. The reactants are isolated from the vacuum system... 

Gruters A, I Allemand D, Heidemann PH, Schurnbrand P. Incidence of iodine contamination in neonatal transient hyperthyrotropinemia. Eur J Pediatr 1983 140(4) 299-300. 

One of the biggest problems with FBI procedures whether automated or otherwise, has been iodine contamination, both in the patient and the operator, as well as in the environment in which the test is carried out. There are several reviews (A4, Cl, H6) that adequately list the interferences (including iodine in various forms) with FBI procedure. One of the most comprehensive reviews of the artifactual and physiological factors affecting serum FBI in recent years is the publication by Acland (A4). In a recent study on FBI (F2), iodine contamination was found in 17.5% of euthyroid patients, many of whom had clinically feasible FBI levels. As alternative techniques are now available, it is clear that FBI is an unsatisfactory screening procedme for determining thyroid function. 

The problem with iodine contamination had been recognized many years ago and led to the development in 1951 by Man et ah (M5) of the serum butanol-extractable iodine (BEI) assay. The principle of this assay is that the serum proteins are precipitated in acidified butan-l-ol and the iodinated compounds are extracted into the alcoholic phase. A very concentrated alkali wash is then used, which removes inorganic iodide and iodotyrosine, if present. The rest of the assay is similar to the FBI technique. Although it was found that the BEI correlates better with clinical status than did the FBI, it was also acknowledged that it did not remove interferences due to organic iodides, such as iodine-containing contrast media (M4), although another study found that the BEI was less susceptible than was FBI to interferences from... 

The Ts resin uptake and related procedures are theoretically unaffected by iodine contamination of the specimen or the glassware, as the final measurement is a radioactivity count. This is confirmed in practice with one minor exception, in which the contrast medium, Oragrafin, was found to increase T3 resin uptake and a resin sponge technique (BIO). 

I-Iabeled iodine contaminating the labeled T3 would be a problem with this method. Absolute FT3 is obtained by simple calculation. The alternative and preferred technique is to dialyze unlabeled T3 from the serum and carry out an RIA on the dialyzate. 

P2. Pannall, P. R., Minnaar, P. C., and Neser, A. T., Iodine contamination of the serum protein-bound iodine incidence and clinical significance. J. Clin. Pathol. 27, 319-322 (1974). 

P8. Pileggi, V. J., Norman, D. L., Orville, J. G., and Henry, R. J., Determination of iodine compounds in serum. I. Serum thyroxine in the presence of some iodine contaminants. J. Clin. Endocrinol. Metab. 21, 1272-1279 (1961). 

Fig. 18.20 The concentrations of iodine and of other halogens (F, Cl, Br) decrease with depth below the surface of the ordinary H6 chondrite ALHA 77258. The pattern is attributable to the deposition of CH I molecules from the atmosphere to the surface of this meteorite followed by diffusion of the iodine to a depth of about 6.5 mm below the surface. The amount of iodine contamination of the surface of a meteorite increases with increasing exposure time, whereas the contamination with F, Cl, and Br decreases with distance from the coast (Data from Langenauer and Krahenbuhl 1993)...

Loss of positive iodine contamination control and potential, slow spread to other Zone 1 SCBs, Zone 2A, Zone 2, MER and the HCF stack... 

Positive iodine contamination control maintained due to increased charcoal filter iodine removal efficiency... 

Sohd iodine, contaminated with salt, was heated until the iodine vaporized. The violet vapor of iodine was then cooled to yield the pure sohd. Sohd iodine and zinc metal powder were mixed and ignited to give a white powder. Identify each physical change and each chemical change. 

I contamination, however. In experiments where results would be greatly affected by slight iodine contamination of the xenon fraction, this point should be checked more closely. Detailed Procedures 4 and 5 contain examples of other effective means of iodine removal. 

Note 1, The double salt, ammonium ceric sulphate, should not be used for preparing the ceric sulphate reagent. It has been found that with this salt, the addition of chloride ion to the arsenious acid reagent appears to be necessary to obtain the full response, and this procedure can introduce a risk of iodine contamination. 

With the exception of iodine-containing ones, no drug is known to be the cause of hyperthyroidism, The mechanisms by which some drugs, others than iodine-containing ones, provoke hypothyroidism are relatively well documented (36) In this section, we will briefly discuss dysthyroidism as a result of iodine contamination, stressing the role of XRF measurements in its detection. ... 

Habermann J., Leisner B., Witte A., Pickardt C.R., Scriba P.C. 1982. Iodine contamination as a cause of hyperthyroidism or lack of TSH response to TRH stimulation (Results based on a screening investigation) J.Endocrinol.Invest. 5 153-156. 

As stated above, XRF neasurements are useful in the follow-up of patients with hyperthyroidism that follows iodine contaminations, at least in some hands (ll)(Chapter IX). 

Minor practical advantages of XRF can be commented upon. Because the method is dependant upon the presence of stable iodine, scans of the thyroid can be obtained in cases of iodine contamination and as it is independant of thyroid... 

Dr. Braverman told us that iodine-induced thyrotoxicosis could be diagnosed by measuring urinary iodine excretion levels. I would like to comment on this point. If the iodine contamination is of recent onset, urinary iodine will of course be elevated. However, several studies have indicated that after coronary arteriography for instance, iodine in urine will be elevated up to two weeks later. After that period it will rapidly come down to normal excretion levels. My other comment concerns the lowering of thjn-oidal radioactive iodine uptake in patients contaminated with iodine. In some patients with iodine-induced thyrotoxicosis, the radioactive iodine uptake remains elevated. Therefore, a high uptake does not exclude the diagnosis of iodine-induced thyrotoxicosis. 

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