Copper gravimetric analysis

Copper is determined by AA or ICP spectrophotometry of copper(II) hydroxide nitric acid extract. Heating the solid hydroxide dehydrates to CuO. The moles of water loss may be measured by gravimetric analysis. The black CuO residue may be identified by x-ray analysis and physical tests. 

The copper content in cupric compounds is usually determined by gravimetric analysis. In the conventional method, Cu is usually reduced to Cu by the addition of sulfurous acid, ammonium hydrogen sulfite, ascorbic acid, or ferrous sulfate. It is then precipitated as cuprous thiocyanate by the addition of ammonium thiocyanate and estimated gravimetrically. 

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. 

Analytical methods employed in soil chemistry include the standard quantitative methods for the analysis of gases, solutions, and solids, including colorimetric, titrimetric, gravimetric, and instrumental methods. The flame emission spectrophotometric method is widely employed for potassium, sodium, calcium, and magnesium barium, copper and other elements are determined in cation exchange studies. Occasionally arc and spark spectrographic methods are employed. 

Copper and lead in brasses and bronzes. Nitric acid treatment of brass leads to chemical separation of tin as SnOi XH2O after filtration and an ignition procedure, the tin can be gravimetrically determined. Thereafter, the analysis is based upon cathodic deposition of Cu and anodic deposition of PbOi. If copper alone is to be determined, deposition from a pH 4 tartrate medium with hydrazine as the anodic depolarizer gives separation from most common metals. If lead is also to be determined, one uses a concentrated nitric acid medium, from which PbOi is deposited... 

Aqueous solutions of copper(n) salts give a green to blue colour or precipitate in the presence of water-soluble amines . In organic solvents, and preferably in the absence of water, aliphatic amines form a complex with excess of copper(ii) chloride. Although the structure of this complex is unknown, it has composition 2CuCl2. amine, becoming therefore useful for quantitative analysis Amino acids yield complexes with the same salts, which are stabilised by a chelate structure 19. After isolation of the complex, it can be analysed for its copper content gravimetrically or colourimetrically " . 

Method 1. Polymerization of Bis(thiooxamides) with Metal Salts Dithiooxamide, or rubeanic acid as it is commonly referred to in the literature, has been widely used for the quantitative analysis of metals. In particular, copper, nickel, and cobalt form complexes that can be analyzed gravimetrically... 

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