Ethylenediaminetetraacetic acid method

Nickel also is deterrnined by a volumetric method employing ethylenediaminetetraacetic acid as a titrant. Inductively coupled plasma (ICP) is preferred to determine very low nickel values (see Trace AND RESIDUE ANALYSIS). The classical gravimetric method employing dimethylglyoxime to precipitate nickel as a red complex is used as a precise analytical technique (122). A colorimetric method employing dimethylglyoxime also is available. The classical method of electro deposition is a commonly employed technique to separate nickel in the presence of other metals, notably copper (qv). It is also used to estabhsh caUbration criteria for the spectrophotometric methods. X-ray diffraction often is used to identify nickel in crystalline form. 

A method suitable for analysis of sulfur dioxide in ambient air and sensitive to 0.003—5 ppm involves aspirating a measured air sample through a solution of potassium or sodium tetrachloromercurate, with the resultant formation of a dichlorosulfitomercurate. Ethylenediaminetetraacetic acid (EDTA) disodium salt is added to this solution to complex heavy metals which can interfere by oxidation of the sulfur dioxide. The sample is also treated with 0.6 wt % sulfamic acid to destroy any nitrite anions. Then the sample is treated with formaldehyde and specially purified acid-bleached rosaniline containing phosphoric acid to control pH. This reacts with the dichlorosulfitomercurate to form an intensely colored rosaniline—methanesulfonic acid. The pH of the solution is adjusted to 1.6 0.1 with phosphoric acid, and the absorbance is read spectrophotometricaHy at 548 nm (273). 

Metal Content. Two common analytical methods for determining metal content are by titration and by atomic absorption spectrophotometry (aas). The titration method is a complexiometric procedure utilizing the disodium salts of ethylenediaminetetraacetic acid (EDTA). The solvent, indicator. 

Radium in hydrochloric acid solution may be separated effectively by ion exchange methods using cation exchange-resin columns. A weak HCl solution is passed through the column. The absorbed metals on the ion-exchange column are eluted with ethylenediaminetetraacetic acid (EDTA) at pH 6.25 or with ammonium citrate at pH 7.8. With either eluant, radium is eluted last, after removing barium and then lanthanum, calcium, magnesium, and other metals. 

Although the most sensitive line for cadmium in the arc or spark spectmm is at 228.8 nm, the line at 326.1 nm is more convenient to use for spectroscopic detection. The limit of detection at this wavelength amounts to 0.001% cadmium with ordinary techniques and 0.00001% using specialized methods. Determination in concentrations up to 10% is accomplished by solubilization of the sample followed by atomic absorption measurement. The range can be extended to still higher cadmium levels provided that a relative error of 0.5% is acceptable. Another quantitative analysis method is by titration at pH 10 with a standard solution of ethylenediaminetetraacetic acid (EDTA) and Eriochrome Black T indicator. Zinc interferes and therefore must first be removed. 

The TRU-Resin column served to preconcentrate the actinide of interest from urine or digested urine samples. Methods were developed for the analysis of Pu in urine, Am in urine, as well as U and Th in urine. After column washing, the actinides were eluted in a single step, using ethylenediaminetetraacetic acid for Am or Pu, and ammonium bioxalate for the U/Th determinations. Column reusability was quite limited if urine samples were not digested first. 

Official methods have been published for the determination of nitric-perchloric acid-soluble copper in soil [97] and ethylenediaminetetraacetic acid-soluble copper in soil [98]. The former method involves atomic absorption spectrometric evaluation of the acid digest and the second method involves extraction of the soil with an aqueous solution of ammonium EDTA and atomic absorption spectrometric evaluation of the extract. 

Parkash and Bansal reported the detection and determination of microgram quantities of ethylenediaminetetraacetic acid with molybdophosphoric acid by a spectrophotometric method [25]. For the detection of EDTA, 5 to 10 Amberlite IRA-400 resin beads (hydroxide form) were placed on a white spot-plate and blotted dry. One drop of sample solution was added, followed by one drop of 4% molybdophosphoric acid solution. A blue color develops if EDTA is present. For the determination, the sample solution (2 mL, containing 18.6 to 186 pg of EDTA) and 4% molybdophosphoric acid solution (3 mL) are mixed for 5 minutes and diluted to 10 mL with water or sodium acetate-acetic acid buffer solution of pH 2. The absorbance is measured at room temperature at 690 nm against a reagent blank. 

The method is normally performed as follows [32,39] an aqueous solution of suitable oxides or salts is mixed with an a-hydroxycarboxylic acid, such as citric acid, and EG is added to the solution. At heating, an esterification process runs in the system leading to the formation of a stable gel in which the metal ions remain fixed. In the modified Pechini process, ethylenediaminetetraacetic acid (EDTA) has been used to replace citric acid due to its stronger chelating power. 

Some methods for fast chromatographic separation and detection of PolyPs in food, biological samples or water have been proposed (Halliwell et al., 1996 Baluyot and Hartford, 1996 Svoboda and Schmidt, 1997 Bewsler et al., 2001). A single-column chromatographic system with indirect UV detection was elaborated, and the dependencies of PolyP retention on the concentrations of pyromellitic acid and ethylenediaminetetraacetic acid (EDTA) in the mobile phase and on the pH of the eluent were determined (Svoboda and Schmidt, 1997). A high performance liquid chromatography (HPLC) method has also been used for the separation of PolyPs (Lorenz and Schroder, 1999). 

Polymerization. Monomers. The cyclopropane type monomers are prepared either by addition of the dichlorocarbene or by the Simmons-Smith reaction on the corresponding olefins. Most of these compounds have been described. Spiropentane is prepared by the Applequist method (I, 2), by the reaction of zinc with C(CH2Br)4 in alcohol in the presence of ethylenediaminetetraacetic acid (EDTA). This hydrocarbon is purified until a single NMR signal is obtained at t = 9.28. 

Ethylenediaminetetraacetic acid (EDTA, formula 17.2) forms coloured complexes with cations which have chromophoric properties (e.g., Fe, Cr, Cu, Co, Ni). These complexes, which are not very intensely coloured, form the basis of several less sensitive spectrophotometric methods, such as that for chromium(III)... 

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