Iodination methods

Determinations of iodate without pre-oxidation in Pacific seawater by the previous method gave a mean result of 583 ig/l with a standard deviation of 0.23 xg/l. For samples containing between 40 and 60 xg/l, standard deviations of 0.19 xg/l (iodate method with pre-oxidation), 0.12 xg/l (iodate method without pre-oxidation), and 0.43 ig/l (total iodine method) were obtained. 

An alternative iodination method is provided by treatment of the telluride with methyl iodide and sodinm iodide in DMF. ... 

The preparation of alkyl iodides by the phosphorus and iodine method is described in an earlier volume of Organic Syntheses,5... 

For chlorination of the humics at neutral pH, a solution of 11-13 g/L of chlorine at pH 7.5 was used. This solution was prepared by bubbling chlorine gas into a solution of 5.6 g of NaOH in 500 mL of water. Bubbling was continued until the solution was within the pH range 7.5 0.1. For chlorination of the humics at high pH, a solution of 17-20 g/L of chlorine at pH 11.8 was used. This solution was prepared by bubbling chlorine gas into a solution of 11.3 g of NaOH in 500 mL of water. Bubbling was continued until the solution was within the pH range 11.8 0.2. The concentration of chlorine was determined by the starch-iodine method. 

The synthetic methods which are illustrated in this section are (a) the formation of symmetrical 1,4-diketones from 1,3- (or / -)keto esters (Expt 5.104), and (b) a Michael addition reaction involving nitroalkanes and a, /f-unsaturated ketones (Expt 5.105). The synthesis of symmetrical 1,4-diketones from the sodio derivatives of /f-keto esters, or their mono-alkyl derivatives, by treatment with iodine [Method (a)], may be formulated in the following general manner. 

Starch was determined colorimetrically by Whistler s iodine method using amylose from corn starch (G.R. TCI Chemical Co.) as a standard (10). 

The I2-starch reaction is the basis of a spectrophotometric assay at 640 nm with amylose standards. A similar Congo red method is less precise than the iodine method, but it has the advantage of insensitivity to the DP, molecular size, and shape. The Congo red assay can therefore be supple-... 

Reaction mixture Titration method Radioactive iodine method Optical densty at 470 mp ... 

Procedure Setup the chlorine generating apparatus as illustrated in Preparation 2 Iodine, method 3. Note your chlorine generator does not have to be as fancy as the apparatus illustrated, but your system should be similar in design. You can use latex tubing, PVC pipes and other plastic devices as well, steel pipes can be used, but other metals should be avoided due to corrosion. Also, observe the chlorine generator utilizing an electrochemical method. The electrochemical method is sufficient to produce laboratory quantities of gas (see the illustration). 

Other synthetic routes reported involve the interactions of trifluoro-phosphine metallates and iodine (method E), displacement of carbon monoxide, alkenes, etc. by PF3 from the corresponding halide complexes (method F), addition of PF3 to dinuclear halogeno-bridged PF3 complexes at low temperatures (method G), and treatment of a metal hydrido- PF3 complex with iodoform (method H). 

Position of the sampie vessei. Although the position of the sample container with respect to the transducer is not a characteristic variable of US application, it determines the amount of energy that is received by the sample. This variable, exclusive of ultrasonic baths, should be optimized in both DUSAL and CUSAL methods. When only one sample is leached, the precision is not affected provided the sample vessel is always in the same position — cavitational effects can be maximal or not in this situation, however. If several samples are simultaneously treated, then the precision is probably affected because the irradiation profile is not uniform throughout the bath. One example is the DUSAL of cadmium and lead from foods, where the iodine method was used to locate the best position for cavitational effects [5]. This requires the use of mapping techniques. 

Mixed dihalides such as iodochlorides have been prepared by treating a dichlotide or bromochlorlde with one equivalent of sodium Iodide (50-90%). Mixtures of dichloride, lodochloride, and diiodide may result. 1,2-Dihalides yield only the olefin and iodine (method 22). 

Interaction of hydrogen iodide and diazoketones forms methyl ketones with the liberation of nitrogen and iodine (method 228). If the diazoketone is treated with bromine, then a dibromomethyl ketone, RCOCHBtj, is formed, ... 

Free radicals react most efficiently with other free radicals, and the chemicals that have relatively stable free radicals, such as 2,2-diphenyl-1-pricylhydrazyl (DPPH), could be used, in principle, to quantitatively estimate the amount of free radicals (DPPH method). The peroxide formed on the surface that derived from free radical could be quantitatively analyzed by the determination of iodine liberated from KI solution, which could be used to calculate the amount of the original free radical from that peroxide was derived (iodine method). 

Antigens, haptens, and antibodies radiolabeled with or are commonly used as tracers in immunoassay. These nuclides can be introduced directly into functional groups normally present in proteins and other macromolecules or into suitable derivatives that can be synthesized by a variety of chemical procedures. The most widely used iodination methods have been direct chemical or enzymic substitution of hydrogen in tyrosine or related groups using chloramine-T or lactoperoxidase, respectively. These methods are described in separate chapters in this volume. 

In the present report, the use of radioiodinated diazotized iodosulfa-nilic acid and a lactoperoxidase-catalyzed iodination method for the labeling and examination of plasma membrane proteins and lipids in cells under humoral immune attack is described. 

The glucose oxidase-lactoperoxidase (GO-LPO) iodination method of Tower et al. was used to produce [ I]hPRL. After purification on a column of Sephadex G-lOO, the major peaks of iodinated material were screened for use in RIA by the talc-resin-TCA test (Fig. I). Peak III material obtained from the Sephadex G-lOO gel filtration purification was the... 

Talc-Resin-Trichloroacetic Acid (TCA) Test Results for -I-Labeled Hormones Prepared by the Glucose Oxidase-Lactoperoxidase (GO-LPO) Iodination Method ... 

Labeled Hormone. Two-milliliter fractions of the peak III material prepared by the GO-LPO iodination method (Fig. 1) should be stored at... 

Fig. 4. Elution pattern of I-labeled rat prolactin, [ I]rPRL (AFP 1-2), prepared by the glucose oxidase-lactoperoxidase iodination method and purified as described in Fig. 1 for human PRL. Before this material was labeled, it had been diluted in phosphate buffer to 100 /xg/ml, aliquoted into separate reaction vials, and stored at -20° for 1 month. During storage, the unlabeled hormone apparently converted to aggregate, as the talc-resin-(TCA) test indicated that no usable monomeric hormone remained available for iodination (cf. Fig. 3) (Tower et al. ).

Reliable, sensitive RIAs can be obtained regularly with the GO-LPO iodination method. A brief outline of the procedure follows. 

Hydroiodic acid, containing hypophosphorous acid, can be used to reduce sulfates quantitatively to hydrogen sulfide, which then can be distilled and determined by the iodine method. ... 

Analytical control followed the Standard Methods recommendations [ 4 ]. Metal ion concentrations were determined by a Perkin-Elmer Model 4000 Atomic Absorption Spectrophotometer with zinz lamp 303-6081, lead lamp 303-6039, and copper lamp 303-6024. Determination of dissolved sulfide was done by titrimetric iodine methods. Phenol determination was performed by distillation/ex-traction method. Total cyanide and ammonia nitrogen were detrmined by the respective distillation/titrimetric methods. 

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