Copper atomic absorption

For copper, atomic absorption was far more sensitive, with an accuracy of 1—2 % compared to an accuracy of 20 % obtained by optical emission. 

Copper. In the presence of sulfur dioxide, copper-protein cloudiness may develop in white wines. Only small amounts of copper (about 0.3 to 0.5 mg/liter) cause cloudiness. Widespread use of stainless steel in modern wineries has reduced copper pickup, but many wineries routinely test their wines for copper. Atomic absorption spectrophotometry is the method of choice (51) although reducing sugars and ethanol interfere, and correction tables must be used (107). To reduce this interference, chelating and extracting with ketone is recommended (108). Lacking this equipment colorimetric procedures can be used, especially with di-ethyldithiocarbamate (3, 4, 6, 9,10, 22,109). Neutron activation analysis has been used for determining copper in musts (110). 

The sensitivity of an atomic absorption line is often described by its characteristic concentration, which is the concentration of analyte giving an absorbance of 0.00436 (corresponding to a percent transmittance of 99%). Eor example. Table 10.11 shows a list of wavelengths and characteristic concentrations for copper. 

Description of Method. Copper and zinc are isolated by digesting tissue samples after extracting any fatty tissue. The concentration of copper and zinc in the supernatant are determined by atomic absorption using an air-acetylene flame. 

M HNO3. The concentration of Cu and Zn in the diluted supernatant is determined by atomic absorption spectroscopy using an air-acetylene flame and external standards. Copper is analyzed at a wavelength of 324.8 nm with a slit width of 0.5 nm, and zinc is analyzed at 213.9 nm with a slit width of 1.0 nm. Background correction is used for zinc. Results are reported as micrograms of Cu or Zn per gram of FFDT. 

Rocha, E. R. P. Nobrega, J. A. Effects of Solution Physical Properties on Copper and Chromium Signals in Plame Atomic Absorption Spectrometry, /. Chem. Educ. 1996, 73, 982-984. 

Analysis of Trace or Minor Components. Minor or trace components may have a significant impact on quaHty of fats and oils (94). Metals, for example, can cataly2e the oxidative degradation of unsaturated oils which results in off-flavors, odors, and polymeri2ation. A large number of techniques such as wet chemical analysis, atomic absorption, atomic emission, and polarography are available for analysis of metals. Heavy metals, iron, copper, nickel, and chromium are elements that have received the most attention. Phosphoms may also be detectable and is a measure of phosphoHpids and phosphoms-containing acids or salts. 

Tests for elements such as arsenic, lead, and copper are specified in the relevant standards. The methods specified are usually of the colorimetric or atomic absorption types. 

BeryUium aUoys ate usuaUy analyzed by optical emission or atomic absorption spectrophotometry. Low voltage spark emission spectrometry is used for the analysis of most copper-beryUium aUoys. Spectral interferences, other inter-element effects, metaUurgical effects, and sample inhomogeneity can degrade accuracy and precision and must be considered when constmcting a method (17). 

Metal Extraction. As with other carboxyhc acids, neodecanoic acid can be used in the solvent extraction of metal ions from aqueous solutions. Recent appHcations include the extraction of zinc from river water for deterrnination by atomic absorption spectrophotometry (105), the coextraction of metals such as nickel, cobalt, and copper with iron (106), and the recovery of copper from ammoniacal leaching solutions (107). 

Colorimetric procedures are often used to determine copper in trace amounts. Extraction of copper using diethyldithiocarbamate can be quite selective (60,62), but the method using dithhone is preferred because of its greater sensitivity and selectivity (50—52). Atomic absorption spectroscopy, atomic emission spectroscopy, x-ray fluorescence, and polargraphy are specific and sensitive methods for the deterrnination of trace level copper. 

Theory. Conventional anion and cation exchange resins appear to be of limited use for concentrating trace metals from saline solutions such as sea water. The introduction of chelating resins, particularly those based on iminodiacetic acid, makes it possible to concentrate trace metals from brine solutions and separate them from the major components of the solution. Thus the elements cadmium, copper, cobalt, nickel and zinc are selectively retained by the resin Chelex-100 and can be recovered subsequently for determination by atomic absorption spectrophotometry.45 To enhance the sensitivity of the AAS procedure the eluate is evaporated to dryness and the residue dissolved in 90 per cent aqueous acetone. The use of the chelating resin offers the advantage over concentration by solvent extraction that, in principle, there is no limit to the volume of sample which can be used. 

In the illustrative experiment described here, copper(II) ions in a brine solution are concentrated from 0.1 to about 3.3 ppm prior to determination by atomic absorption spectrophotometry. 

Procedure. Allow the whole of the sample solution (1 L) to flow through the resin column at a rate not exceeding 5 mL min . Wash the column with 250 mL of de-ionised water and reject the washings. Elute the copper(II) ions with 30 mL of 2M nitric acid, place the eluate in a small conical flask (lOOmL, preferably silica) and evaporate carefully to dryness on a hotplate (use a low temperature setting). Dissolve the residue in 1 mL of 0.1 M nitric acid introduced by pipette and then add 9 mL of acetone. Determine copper in the resulting solution using an atomic absorption spectrophotometer which has been calibrated using the standard copper(II) solutions. 

Evenson, M. A. and Anderson, C. T., Jr. Ultramlcro Analysis for Copper, Cadmium and Zinc In Human Liver Tissue by Use of Atomic Absorption Spectrophotometry and the Heated Graphite Tube Atomizer". Clin. Chem. (1975), 2, 537-543. 

J. "Determination of Copper In Serum With a Graphite Rod Atomizer for Atomic Absorption Spectrophotometry". Anal. Chlm. Acta (1971), 263-269. 

Hohnadel, D. C., Sunderman, F. W., Jr., Nechay, M. W., and McNeely, M. D. "Atomic Absorption Spectrometry of Nickel, Copper, Zinc, and Lead In Sweat from Healthy Subjects during Sauna Bathing". Clin. Chem. (1973), 19, 1288-1292. 

McIntyre, N. S., Cook M. G., and Boase, D. G. "Flameless Atomic Absorption Determination of Cobalt, Nickel, and Copper - A Comparison of Tantalum and Molybdenum Evaporation Surfaces". Anal. Chem. (1974), 46, 1983-1987. 

Stevens, B. J. "Biological Applications of the Carbon Rod Atomizer In Atomic Absorption Spectroscopy. 2. Determination of Copper In Small Samples of Tissue". Clin. Chem. (1972), 18, 1379-1384. 

Analysis of Corexit 9527. Corexit 9527 in natural waters can be analyzed. The method is based on the formation of a Z>w(ethylenediamine) copper(II) complex, extraction of the complex into methylisobutylketone, and atomic absorption spectroscopy [1564]. The method is suitable for a concentration range of 2 to 100 mg/liter, with a precision as low as 5% relative to standard deviation for samples in the middle- to high range. Only a small sample volume (10 ml) is required. The sensitivity may be substantially increased for trace analysis by increasing the sample volume. 

Pauwels j, De Angelis L, Peeteemans F, Ingelerecht C (1990) Determination of traces of silver in copper by direct Zeeman graphite furnace atomic absorption spectrometry. Fresenius J Anal Chem 337 290-293. 

Next, reductive amination (step 4 in scheme 1) was exchanged with copper catalyzed palladium coupling (step 2 in scheme 1). Atomic absorption analysis for palladium in RWJ-26240 samples prepared by scheme 2 indicated that the level of palladium was reduced to an acceptable level. This improvement may be due to the two reduction steps subsequent to the use of palladium in scheme 2.177 The final major modification to the reaction scheme was the substitution of NaBH4 for NaBH3CN. The yield of product (60%) was determined by HPLC (Method 2). Reductive alkylation with formalin/NaBH4 afforded a pharmaceutically acceptable drug substance. 

Silver acetylide is a more powerful detonator than the copper derivative, but both will initiate explosive acetylene-containing gas mixtures [1]. It decomposes violently when heated to 120-140°C [2], Formation of a deposit of this explosive material was observed when silver-containing solutions were aspirated into an acetylene-fuelled atomic absorption spectrometer. Precautions to prevent formation are discussed [3], The effect of ageing for 16 months on the explosive properties of silver and copper acetylides has been studied. Both retain their hazardous properties for many months, and the former is the more effective in initiating acetylene explosions [4],... 

Ho M.D., Evans G.J. Operational speciation of cadmium, copper, lead and zinc in the NIST standard reference materials 2710 and 2711 (Montana soil) by the BCR sequential extraction procedure and flame atomic absorption spectrometry. Anal Commun 1997 34 353-364. 

Mercury was determined after suitable digestion by the cold vapour atomic absorption method [40]. Lead was determined after digestion by a stable isotope dilution technique [41-43]. Copper, lead, cadmium, nickel, and cobalt were determined by differential pulse polarography following concentration by Chelex 100 ion-exchange resin [44,45], and also by the Freon TF extraction technique [46]. Manganese was determined by flameless atomic absorption spectrometry (FAA). 

The following analytical techniques seem to be adequate for the concentrations under consideration copper and nickel by Freon extraction and FAA cold vapour atomic absorption spectrometry, cobalt by Chelex extraction and differential pulse polarography, mercury by cold vapour atomic absorption absorptiometry, lead by isotope dilution plus clean room manipulation and mass spectrometry. These techniques may be used to detect changes in the above elements for storage tests Cu at 8 nmol/kg, Ni at 5 nmol/kg, Co at 0.5 nmol/kg, Hg at 0.1 nmol/kg, and Pb at 0.7 nmol/kg. 

Other methods reported for the determination of beryllium include UV-visible spectrophotometry [80,81,83], gas chromatography (GC) [82], flame atomic absorption spectrometry (AAS) [84-88] and graphite furnace (GF) AAS [89-96]. The ligand acetylacetone (acac) reacts with beryllium to form a beryllium-acac complex, and has been extensively used as an extracting reagent of beryllium. Indeed, the solvent extraction of beryllium as the acety-lacetonate complex in the presence of EDTA has been used as a pretreatment method prior to atomic absorption spectrometry [85-87]. Less than 1 p,g of beryllium can be separated from milligram levels of iron, aluminium, chromium, zinc, copper, manganese, silver, selenium, and uranium by this method. See also Sect. 5.74.9. 

To determine down to 2.4 xmol/l of copper in seawater, Nishoika et al. [282] complexed the copper with di-ethyl-dithio carbamate, precipitated with ferric hydroxide, filtered off and dissolved the precipitate with nitric acid, and determined copper by electrothermal atomic absorption spectrometry. 

A Cis column loaded with sodium diethyldithiocarbamate has been used to extract copper and cadmium from seawater. Detection limits for analysis by graphite furnace atomic absorption spectrometry were 0.024 pg/1 and 0.004 xg/l, respectively [283]. 

---