Electrothermal Atomic Absorption Spectrometric Determination Research Articles

Effects of ageing of pyrolytically coated tubes on the determination of refractory elements by electrothermal atomisation atomic absorption spectrometry

The quality of the pyrolytic coating of graphite tubes is shown to be of prime importance in the electrothermal atomisation atomic absorption spectrometric determination of refractory elements in complex matrices. For molybdenum in a plant matrix the shortcomings due to progressive degradation of the coating can be circumvented by signal integration. The problems encountered with chromium in several matrices are related to the irreproducible quality of the coating between different sets of tubes supplied by the same manufacturer. For the determination of barium in sea water, pyrolysis at 1800 °C efficiently eliminates background absorption. With an increase in tube porosity, due to degradation of the coating, there is a drastic increase in the background signal that can be corrected only with a Zeeman device.

X-ray photoelectron spectroscopic study of the mechanism of palladium matrix modification in the electrothermal atomic absorption spectrometric determination of lead and bismuth

The mechanism of palladium matrix modification is studied for the determination of lead and bismuth by graphite-furnace atomic absorption spectrometry. The binding energies of the charring products for lead and bismuth in the presence or absence of palladium obtained at the initial stage of atomization were measured. The binding energies indicated the formation of PbPd and BiPd bonds, thus explaining the increase in appearance temperatures of lead and bismuth in the presence of palladium.

The electrothermal atomic absorption spectrometric determination of lead, manganese, vanadium and molybdenum in sea water with ascorbic acid to reduce matrix effects

The effect of ascorbic acid on the response of several metals in sea water obtained by graphite-furnace atomic absorption spectrometry was evaluated from the variation of peak time and the sensitivity. Matrix interferences from sea water in the determination of lead, manganese, vanadium and molybdenum were suppressed by addition of 10% (w/v) ascorbic acid solution to the sample in the furnace. Matrix effects on the determination of cobalt and copper could not be removed in this way. A direct method for the determination of lead, manganese, vanadium and molybdenum in sea water is proposed.

Electrothermal atomic absorption spectrometric determination of aluminum in serum with a new technique for protein precipitation.

We have studied the electrothermal atomic absorption measurement of aluminum in serum samples by direct analysis with standard additions and the use of a matrix modifier. We have also measured aluminum by analysis of the supernate after pretreatment of serum with concentrated nitric acid to precipitate proteins, and have compared the results obtained by these two techniques. Both appear to eliminate interferences arising from the serum matrix. We quantified the aluminum by utilizing a stabilized temperature (L'vov) platform. Within-run precision (CV) for the standard-additions method was 16.6% (means = 6.5 micrograms/L) and 6.0% (means = 86.8 micrograms/L) and for the protein precipitation method was 10.1% (means = 10.9 micrograms/L) and 4.2% (means = 88.5 micrograms/L). Linearity of the standard curve extended from 0 to 120 micrograms/L for the standard-additions method and from 0 to 100 micrograms/L for the protein precipitation method. Samples from 38 patients were analyzed by both techniques, and linear regression analysis yielded the equation y (protein precipitation) = 1.02 X (standard additions) + 2.04.

Electrothermal atomic absorption spectrometric determination of traces of chromium, nickel, iron and beryllium in aluminum and its alloys without preliminary separation

Graphite-furnace a.a.s, is used for the determination of > 0.0007% Cr, > 0.01% Ni, > 0.007% Fe and > 0.0002% Be in aluminum and its alloys. The samples are dissolved in hydrochloric acid and processed directly after addition of a slight molar excess of diammonium-EDTA over aluminum.

Electrothermal Atomic Absorption Spectrometric Determination of Selenium in Foods and Diets

The validity of 2 electrothermal atomic absorption spectrometric methods for determination of selenium in foods and diets was tested. By using 0.5% Ni(II) as a matrix modifier to prevent selenium losses during the ashing step, it was shown that selenium can be determined in samples containing greater than or equal to 1 microgram Se/g dry wt without organic extraction. The mean recovery tested, using NBS Bovine Liver, was 98%; recovery of added inorganic selenium in Bovine Liver matrix was 100%. In addition, this method gave values closest to the median value of all participating laboratories using hydride generation AAS or the spectrofluorometric method in a collaborative study on high selenium wheat, flour, and toast samples. For samples with concentrations less than 1 microgram Se/g dry wt, separation of selenium from interfering Fe and P ions by organic extraction was necessary. Using inorganic 75Se in meat and human milk matrixes, an ammonium pyrrolidine dithiocarbamate-methyl isobutyl ketone-extraction system with added Cu(II) as a matrix modifier yielded the best extraction recoveries, 97 and 98%, respectively. Accuracy and precision of the method were tested using several official and unofficial biological standard materials. The mean accuracy was within 4% of the certified or best values of the standard materials and the day-to-day variation was 9%. The Se/Fe or Se/P interference limits proved to be low enough not to affect selenium determinations in practically all foods or diets. The practical detection limit of the method was 3 ng Se/g dry wt for 1.0 g dry wt samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrothermal atomic absorption spectrometric determination of ng g -1 levels of cadmium in bone after dithizone extractions

After removal of lipid and acid digestion of bone samples, cadmium is separated from the matrix by two extractions with dithizone in carbon tetrachloride. The first extraction at pH 3–3.5 removes cadmium from the matrix; the second extraction, at pH 8.5 in the presence of 2-hydroxyethylethylenediaminetriacetic acid, is needed to prevent suppression of the cadmium signal by zinc. Cadmium is finally measured in the back-extract into 0.24 M hydrochloric acid. Less than 10 ng g -1 cadmium in fresh bone can be determined within a relative standard deviation of 10%.

Electrothermal atomic absorption spectrometric determination of trace lead, copper and manganese in aluminum and its alloys without preliminary separation

Graphite-furnace atomic absorption spectrometry is used for the determination of >0.001% of lead, copper and manganese in aluminum and its alloys. The samples are dissolved in hydrochloric acid and analyzed directly after addition of a slight excess of (NH 4) 2 EDTA over aluminum. Sample and standard solutions must contain equal amounts of EDTA.

Electrothermal atomic absorption spectrometric determination of selenium in blood serum and seminal fluid after protein precipitation with trichloroacetic acid

The determination of selenium in body fluids by electrothermal atomic absorption spectrometry (e.a.a.s.) suffers from severe spectral interferences from phosphate which results in overcompensation when a continuum-source background corrector is used. The separation of selenium from phosphate by protein precipitation with trichloroacetic acid allows the determination of selenium in blood serum and seminal fluid by e.a.a.s. after thermal stabilization with silver, nickel or copper. The selenium concentration in seminal fluid from healthy, fertile Norwegian donors ranged from 0.09 to 1.30 μmol l -1 with a group average of 0.44 μmol l -1 ( n = 15).

Ion-exchange resin beads as solid standards for the electrothermal atomic absorption spectrometric determination of metals in hair

Summary The addition of known masses of copper or aluminium to individual beads of ion-exchange resin provides a stable matrix of known metal content for use in calibrating the carbon-furnace atomic absorption spectrometric determination of trace metals in individual hair segments. Relative standard deviations of 8–11% are obtained for 0.5–1.5 ng of copper and aluminium. The results support the suggestion that aqueous solutions are suitable for calibrating the determination of certain trace elements in hair by this method.

Atomic absorption spectrometric determination of the total content and distribution of copper and gold in synovial fluid from patients with rheumatoid arthritis

Summary Rapid, simple and sensitive methods are described for electrothermal atomic absorption spectrometric determination of copper and gold in synovial fluid. The procedures were used to determine the two metals in 13 samples of synovial fluid from patients with rheumatoid arthritis; in one of these samples the distribution of the two metals among the proteins was established by gel filtration.

Thermal stabilization of inorganic and organically- bound tellurium for electrothermal atomic absorption spectrometry

The thermal stabilization of inorganic tellurium(IV) and organically-bound tellurium for electrothermal atomic absorption spectrometric determination of the element was studied with the use of the isotope tellurium-127m. Of the 19 metals and potassium iodide tested, 15 metals had a stabilizing effect on inorganic tellurium; among the 9 metals tested with organically-bound tellurium, only 3 exhibited an effect. The most effective metals for stabilizing inorganic tellurium were cadmium, copper, palladium, platinum and zinc, while the best agents for stabilization of organically-bound tellurium were silver, palladium and platinum; in the presence of palladium and platinum, tellurium in both forms could be heated in the graphite tube to 1050°C without losses. Attempts were made to determine tellurium in human whole blood and garlic, but the concentrations were found to be below the detection limits of 3 ng ml -1 and 140 ng g -1, respectively.

Electrothermal atomic absorption spectrometric determination of cobalt in steel after chloroform extraction of its 1-nitroso-2-naphthol complex

Direct determination of μg g -1 levels of cobalt in steels and corrosion products by electrothermal atomic absorption is difficult because of suppression of the cobalt signal by mineral acids and other metals. Extraction or cobalt with 1-nitroso-2-naphthol into chloroform in the presence of citrate overcomes this problem. Samples (0.4–10 mg) may be dissolved in a variety of acids, and a detection limit of 0.005 μg g -1 in the chloroform extract is obtained.