Copper determination precision

The method of isotopic labelling is employed to determine the presence of traces of copper with precision. An ICP/MS installation was employed. The results of the experiment rely upon the ratio of the intensities of the peaks corresponding to the masses 63 and 65 of the two isotopes 63Cu and 65Cu of elemental copper. The experiment is described below. First, an injection of a small quantity of the unknown solution was injected. The intensities of 63Cu and 65Cu are 82 908 and 37 092 respectively (arbitrary units). 

Fig. 20. a Active site of E. coli amine oxidase. The polypeptide backbone is shown as a continuous coil, colored white for subunit A and grey for subunit B. Conserved residues are shown in all-atom representation, and the copper is shown as a green van der Waals dot surface. The position of TPQ in crystal form I is illustrated in green, coordinated to the copper. The precise location and orientation of the TPQ ring are not completely determined at the resolution of the current studies of crystal form II, and its general location is indicated by a yellow phenyl ring, close to the putative catalytic base Asp 383 (red). In crystal form II, TPQ is not a copper ligand, and the copper coordination is completed by two water molecules, shown in yellow (with permission from [28])... 

Flow injection with FAAS was studied for the determination of copper, zinc, and iron in parotid saliva of normal subjects by Burguera et al. (1986). The sample was injected as a discrete slug into a carrier stream of double distilled and deionized water, and standards were prepared in solutions containing physiological concentrations of sodium, potassium and albumin. Sample size for copper determination was 50 nL, dispersion tube length 60 cm and the carrier flow rate 1.5 mUmin. At a mean copper concentration of around 70 fiQlL the within batch precision was 2.2% (RSD) and the day to day precision 3.9% (RSD). 

Its formation may be used for the quantitative analysis of the product. Indeed, a means to quantitatively determine it is to proceed through a polarimetric measurement. It is recommended to carry it out in an alkaline solution of copper(II) sulfate. There is an enhancement of the rotation and, hence, an enhancement of the determination precision by forming the copper complex. Of course, the rotation is compared to a reference in order to interpret the result. 

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. 

It should be observed that every element except the powder system in the recovery system is chosen for favorable shock properties which can be confidently simulated numerically. The precise sample assembly procedures assure that the conditions calculated in the numerical simulations are actually achieved in the experiments. The influence of various powder compacts in influencing the shock pressure and mean-bulk temperature must be determined in computer experiments in which various material descriptions are used. Fortunately, the large porosity (densities from 35% to 75% of solid density) leads to a great simplification in that the various porous samples respond in the same manner due to the radial loading introduced from the porous inclusion in the copper capsule. 

Accuracy. Precision and Conditions for Thermal and Fast NAA for Al. Cl Mn Determination of Pellet Weight and of the Copper/Oxygen Ratio to... 

Because of- the similarity in the backscattering properties of platinum and iridium, we were not able to distinguish between neighboring platinum and iridium atoms in the analysis of the EXAFS associated with either component of platinum-iridium alloys or clusters. In this respect, the situation is very different from that for systems like ruthenium-copper, osmium-copper, or rhodium-copper. Therefore, we concentrated on the determination of interatomic distances. To obtain accurate values of interatomic distances, it is necessary to have precise information on phase shifts. For the platinum-iridium system, there is no problem in this regard, since the phase shifts of platinum and iridium are not very different. Hence the uncertainty in the phase shift of a platinum-iridium atom pair is very small. 

Marechal CN, Telouk P, Alberede F (1999) Precise analysis of copper and zinc isotopic compositiorrs by plasma-source mass spectrometry. Chem Geol 156 251-273 Martin P, Hancock GJ, Paulka S, Akber RA (1995) Determination of Ac-227 by alpha-particle spectrometry. Appl Radiat Isot 46 1065-1070... 

The results obtained by various calibrations in the determination of nickel and copper are shown in Tables 1.2 and 1.3. Table 1.4 gives the differences between sampling devices for copper, as determined by each participant, when these are significant at the 95% and 90% levels of confidence. Only the results of participants that had acceptable analytical performance, as measured by precision and agreement with contemporary consensus values for deep North Atlantic waters (Table 1.5), were used for drawing conclusions. 

Spencer and Brewer [144] have reviewed methods for the determination of nitrite in seawater. Workers at WRc, UK [ 145] have described an automated procedure for the determination of oxidised nitrogen and nitrite in estuarine waters. The procedure determines nitrite by reaction with N-1 naphthyl-ethylene diamine hydrochloride under acidic conditions to form an azo dye which is measured spectrophotometrically. The reliability and precision of the procedure were tested and found to be satisfactory for routine analyses, provided that standards are prepared using water of an appropriate salinity. Samples taken at the mouth of an estuary require standards prepared in synthetic seawater, while samples taken at the tidal limit of the estuary require standards prepared using deionised water. At sampling points between these two extremes there will be an error of up to 10% unless the salinity of the standards is adjusted accordingly. In a modification of the method, nitrate is reduced to nitrite in a micro cadmium/copper reduction column and total nitrite estimated. The nitrate content is then obtained by difference. 

Boyle and Edmond [679] determined copper, nickel, and cadmium in 100 ml of seawater by coprecipitation with cobalt pyrrolidine dithiocarba-mate and graphite atomiser atomic absorption spectrometry. Concentration ranges likely to be encountered and estimated analytical precisions (lcr) are l-6nmol/kg ( 0.1) for copper, 3-12nmol/kg ( 0.3) for nickel, and 0.0-1.1 nmol/kg ( 0.1) for cadmium. 

Ammonium pyrrolidine dithiocarbamate (APDC) chelate coprecipitation coupled with flameless atomic absorption provides a simple and precise method for the determination of nanomol kg 1 levels of copper, nickel, and cadmium in seawater. With practice, the method is not overly time-consuming. It is reasonable to expect to complete sample concentration in less than 20 min, digestion in about 4 h, and sample preparation in another hour. Atomic absorption time should average about 5 min per element. Excellent results have been obtained on the distribution of nickel and cadmium in the ocean by this technique. 

Bruland et al. [122] have shown that seawater samples collected by a variety of clean sampling techniques yielded consistent results for copper, cadmium, zinc, and nickel, which implies that representative uncontaminated samples were obtained. A dithiocarbamate extraction method coupled with atomic absorption spectrometry and flameless graphite furnace electrothermal atomisation is described which is essentially 100% quantitative for each of the four metals studied, has lower blanks and detection Emits, and yields better precision than previously published techniques. A more precise and accurate determination of these metals in seawater at their natural ng/1 concentration levels is therefore possible. Samples analysed by this procedure and by concentration on Chelex 100 showed similar results for cadmium and zinc. Both copper and nickel appeared to be inefficiently removed from seawater by Chelex 100. Comparison of the organic extraction results with other pertinent investigations showed excellent agreement. 

Yamamoto et al. [33] applied this technique to the determination of arsenic (III), arsenic (V), antimony (III), and antimony (V) in Hiroshima Bay Water. These workers used a HGA-A spectrometric method with hydrogen-nitrogen flame using sodium borohydride solution as a reductant. For the determination of arsenic (III) and antimony (III) most of the elements, other than silver (I), copper (II), tin (II), selenium (IV), and tellurium (IV), do not interfere in at least 30 000-fold excess with respect to arsenic (III) or antimony (III). This method was applied to the determination of these species in sea water and it was found that a sample size of only 100 ml is enough to determine them with a precision of 1.5-2.5%. Analytical results for surface sea water of Hiroshima Bay were 0.72 xg/l, 0.27 xg/l, and 0.22 xg/l, for arsenic (total), arsenic (III), and antimony (total), respectively, but antimony (III) was not detected. The effect of acidification on storage was also examined. 

An evaluation of the obtained data indicated that the mean values found for iron, copper, and zinc are within the values presented in literature. The main assets of the presented method lie in its simplicity and the practicality of determining analytes from samples of various origins. Suitability of the developed IC method was supported by validation results as shown in Table 1. Generally, very good results of precision (RSD below 5%) and recoveries (above 90%) were evaluated. 

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