Direct Graphite Furnace Atomic Absorption Research Articles

Determination of arsenic in edible oils by direct graphite furnace atomic absorption spectrometry

A direct analytical method of arsenic content in edible oil with graphite furnace atomic absorption spectrophotometer was studied. Edible oil was diluted with n-heptane followed by the determination of arsenic with Zeeman graphite furnace atomic absorption spectrophotometer and transverse heated graphite atomizer (THGA). The arsenic organic AAS standard solution was used as calibration standard, and bis (benzonitrile) dichloro palladium solution was used as a matrix modifier. The results showed that the optimal ashing and atomizing temperatures were 1200°C and 2300°C, respectively. The detection limit was estimated to be 0.010 ppm, and the percentages of recovery for the spike of 0.05, 0.10 and 0.20 ppm arsenic to salad oil, fish oil, palm oil, and lard were 91.2-94.3%, 94.7-95.6%, 94.2-96.7% and 93.3-94.1%, respectively. With the use of this method, thirty edible oils were analyzed and the arsenic contents were found to be below the detection limits.

Determination of copper in edible oils by direct graphite furnace atomic absorption spectrometry

A simple method for determination of copper in edible oils was developed, using a polarized Zeeman graphite furnace atomic absorption spectrophotometer and a pyro graphite tube. Edible oils were diluted with 2% lecithin-cyclohexane and analyzed directly by the standard addition method. The optimal ashing and atomizing temperatures were 900°C and 2700°C, respectively. A standard solution diluted with 2% lecithin-cyclohexane was superior to salad oil or cyclohexane. Results were best measured when the concentration of lecithin in cyclohexane was higher than 2%. The detection limit of this method was 2.0 ng/mL. The respective range of recovery of copper was 85.5-90.0% and 86.0-93.0% in salad oil and lard which were fortified with 10, 20 and 40 ng Cu/mL respectively using the standard addition method.

Determination of Lead in Lipstick by Direct Solid Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry: Comparison of Two Digestion Methods

A new analytical procedure for the determination of lead in lipstick has been developed using direct solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (SS HR CS GFAAS). The performance of this method has been compared to acid digestion methods for sample preparation, with or without hydrofluoric acid (HF) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Good reliability was obtained for all three methods; the results obtained for certified reference materials with concentrations between 1 and 20 ppm were in agreement with the certified values. However, for materials with complex matrices, such as pearl or Ca-Na borosilicate, only ICP-MS with HF sample digestion or AAS with direct solid sampling allowed complete recovery of lead. To avoid the use of hazardous acids, the development of SS HR CS GFAAS is an interesting alternative. With the AAS method, a characteristic mass of 13.2 pg of lead was obtained, and the limit of detection was 0.005 µg/g. The performance of the method was evaluated by determining lead in lipstick. The use of the solid sampling technique constitutes a good alternative for accurate and rapid determination of lead content in lipstick and cosmetic raw materials, with a suitable limit of detection and a reduced risk of contamination or of analyte loss. Another alternative would be to use ICP-MS determination in conjunction with microwave-assisted acid digestion without the use of HF, which implies accepting a quantification of “nearly total” lead, closer to a “bio-extractible” fraction.

Crosslinked Carboxymethyl Starch Based Solid Phase Extraction Combined with Direct Slurry Sampling Graphite Furnace Atomic Absorption Spectrometry for the Determination of Trace Lead in Water Samples

A new method of solid phase extraction (SPE), using crosslinked carboxymethyl starch as adsorbent, combined with direct slurry sampling graphite furnace atomic absorption spectrometry (ss-GFAAS) has been developed for the high sensitive determination of lead in water samples. The SPE adsorbent loaded with the analyte was made in to slurry with the assistance of Triton X-100. The slurry was directly injected into the graphite furnace for the determination of lead. Variables such as the pH, sample volume, and amount of Crosslinked Carboxymethyl Starch (CCMS) were investigated. The detection limit (3σ) was 0.082 μg L-1 and the RSD was 4.9% (n = 11, c = 1.0 mg L-1) for Pb(II). The enrichment factor was 100 at a sample volume of 100 mL. The proposed method has been applied to the determination of lead in environmental water reference materials and two water samples with satisfied results.

The determination of cadmium in oils and fats by direct graphite furnace atomic absorption spectrometry. Results of collaborative studies and the standardized method

Abstract A description is given of the development by collaborative study of a standardised method for the determination of cadmium in crude and refined oils and fats by graphite furnace atomic absorption spectrometry. The procedure is rapid and sensitive allowing determination at levels of 1 to 10 μg/kg.

Graphite Furnace Atomic Absorption Spectrometry Determination and On-line Preconcentration of Palladium

Abstract Palladium was determined in pharmaceuticals by direct graphite furnace atomic absorption spectrometry (GFAAS) method. The detection limit was 0.1 μg/g in 5% solution; the recovery of 0.5–2.0 μg/g Pd spike was close to 100%. The flow injection GFAAS method was worked out using oxime and iminodiacetic acid ethyl cellulose (IDAEC) microcolumns for preconcentration of Pd in aqueous and 50% methanol solutions. The optimal pH range for preconcentration was 2–5. At 20-fold enrichment the detection limits for Pd were 0.39 μg/liter for oxime cellulose and 0.42 μg/liter for IDAEC.

Direct analysis of solid samples by graphite furnace atomic absorption spectrometry with a transversely heated graphite atomizer and D 2 -background correction system (SS GF-AAS)

An instrumental design for the analysis of heavy metals in solid samples (certified reference materials, river sediments, cements) by direct graphite furnace atomic absorption spectroscopy (SSGF-AAS) is presented and outlined. A high performance atomic absorption spectrometer with a D2-background corrector and a transversely heated graphite atomizer was modified. Solid sampling was achieved by a mechanical module combined with an ultra microbalance. Cadmium, lead and chromium in different samples (sample weights between 20–400 μg) have been determined in the μg/g- to ng/g-range with the graphite-platform technique. Different ways of calibration and inhomogeneity problems are discussed. The precision of SSGF-AAS is equal to the precision of the conventional AAS-technique with chemical digestion (microwave digestion system, Zeeman-AAS). It is shown that SSGF-AAS is a reasonable alternative to the conventional technique for selected analytical problems.

On-line coupling of ion chromatography and atomic spectrometry and use of direct graphite furnace atomic absorption spectrometry as new tools for ultra trace determinations in refractory metals

On-line coupling of inductively coupled plasma (ICP) techniques such as ICP-AES and ICP-MS with ion chromatography (IC) offers unique features for ultra-trace analysis. An on-line preconcentration procedure based on cation exchange enables sub-ng/g analysis in complex matrices like molybdenum and tungsten. The best dissolution reagent for these matrices is hydrogen peroxide, which can be cleaned to ultra high purity with the same metal free chromatography equipment used for the preconcentration. Preconcentration is possible for elements that show cationic reactions within acidic peroxide containing solutions. In this study 28 elements detrimental for microelectronics applications are observed. A comparison of the combinations IC-ICP-AES and IC-ICP-MS with glow discharge mass spectrometry (GDMS) for the analysis of today's purest tungsten samples shows the analytical power and accuracy of the coupled devices. Graphite furnace atomic absorption spectrometry (GFAAS) as an extremely sensitive analytical technique is applied with and without the same sample pretreatment as used for the on-line coupling. Direct GFAAS measurements of alkali metals are complementary to IC-ICP techniques. The data evaluated with these wet chemical techniques are compared to the usual manufacturers characterisation technique GDMS. With respect to the low concentrations present in these high purity materials (ng/g level in the solid) the discrepancies between all methods are acceptable. The sensitivity of IC-ICP-MS is in most cases far superior to IC-ICP-AES and for some elements also to GDMS. Furthermore the specific advantages of on-line coupling such as the elimination of isobaric interferences in ICP-MS or spectral interferences in ICP-AES are shown for ICP-AES and ICP-MS determinations.

Direct Graphite Furnace–Atomic Absorption Method for Determination of Lead in Edible Oils and Fats: Summary of Collaborative Study

The IUPAC Commission on Oils, Fats, and Derivatives undertook development of a method and collaborative study for the determination of lead in oils and fats by direct graphite furnace-atomic absorption spectrophotometric method. Various types of graphite furnaces were used with or without platform. Twenty-three collaborators from 12 countries participated in the study. The materials tested were edible oils (soybean oil) and fats (cocoa butter) containing lead at 3 concentration levels (low, medium, and high). Each level was represented by 2 batches provided in duplicate (blind coded), so that each collaborator received a total of 24 test samples. Collaborators were instructed to analyze each in duplicate and report both results. Twenty collaborators returned the results of the study. After data from laboratories that did not follow the instructions were excluded, only 16 sets of data were evaluated statistically. The method for determination of lead in oils and fats by direct graphite furnace-atomic absorption spectrophotometry has been adopted first action by AOAC INTERNATIONAL as an IUPAC-AOCS-AOAC method.

Determination of Aluminum in Wines by Direct Graphite Furnace Atomic Absorption Spectrometry

Abstract A simple method for direct routine determination of aluminum in wine by graphite furnace atomic absorption spectrometry is described. This procedure allows good sensitivity by inclusion of a cool-down step before atomization. The detection limit obtained with a single-beam apparatus was 1.5 μg/L. Recoveries of aluminum in red, white, and fortified wines ranged from 91.7 to 109.5%. Aluminum was determined in 98 red table wines from the south of France. The mean aluminum content was 0.763 mg/L (range, 0.25–2.55 mg/L). In addition, the ability of the wine to dissolve the aluminum in the crown cap was shown.

Direct graphite furnace atomic absorption spectrometric determination of metals in sea water: application of palladium modifiers and a fractal approach to their analytical support

Sea water, like other high-salinity matrices, causes severe interferences in the direct determination of metals by graphite furnace atomic absorption spectrometry (GFAAS), even when Zeeman-effect background corrections is applied. A method for eliminating these interferences by the application of mixed modifier system of ammonium oxalate and tetraamminepalladium(II) chloride is presented. In particular these modifiers optimize the direct GFAAS determination of lead and manganese. For cadmium, however, only ammonium oxalate should be used as a modifier. The geometry of the microdistribution of palladium on the palladium-conditioned graphite platform was investigated in order to elucidate possible stabilizing effects of palladium on the analytes which were observed with the different modifiers. Fractal characteristics of the palladium elemental distribution were ascertained by a scanning electron microscope-energy-dispersive x-ray spectrometer image box-counting analysis. The fractal dimension [ D B(0) = 1.77 ± 0.04 and 1.81 ± 0.04] and electron microscopic investigations indicated differences in the structure of palladium deposits on the platform. These variations in the palladium geometry affect the analytes to a certain extent.

Determining Beryllium in Drinking Water by Graphite Furnace Atomic Absorption Spectroscopy

A direct graphite furnace atomic absorption spectroscopy method for the analysis of beryllium in drinking water has been derived from a method for determining beryllium in urine. Ammonium phosphomolybdate and ascorbic acid were employed as matrix modifiers. The matrix modifiers successfully eliminated common chemical interferences in water samples analyzed for beryllium content, as well as interferences encountered during jar testing of beryllium removal by alum coagulation. The method proved to be a simple, accurate, and precise alternative to the method of standard additions. Method detection limit was 0.03 μg/L, with a linear calibration range of 0–6 μg/L.

Determination of cadmium in orthophosphoric acid by graphite furnace atomic absorption spectrometry

Cadmium has been determined in analytical-reagent grade orthophosphoric acids by direct graphite furnace atomic absorption spectrometry with Zeeman background correction. The detection limit was 3.0 pg cadmium, corresponding to 1.0 μg/l of cadmium in the concentrated acid. Most of the acids analyzed contained 2–5 μg/l of cadmium. The method was checked using electrochemical preconcentration of cadmium, followed by flame atomic absorption spectrometry.

Determination of phosphorus in oils and fats by direct graphite furnace atomic absorption spectrometry: results of a collaborative study acid the standardized method

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Determination of lead in oils and fats by direct graphite furnace atomic absorption spectrometry: results of a collaborative study and the standardized method

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Determination of Copper, Iron, and Nickel in Oils and Fats by Direct Graphite Furnace Atomic Absorption Spectrometry: Summary of Collaborative Study

A collaborative study of a method for the determination of copper, iron, and nickel in edible oils and fats by direct graphite furnace atomic absorption spectrometry was recently conducted by the International Union of Pure and Applied Chemistry. The quantitation limits of the method are 5 micrograms/kg for copper and 10 micrograms/kg for iron and nickel. The method has been adopted official first action as an IUPAC-AOAC method.

Determination of copper, iron and nickel in oils and fats by direct graphite furnace atomic absorption spectrometry: results of a collaborative study and the standardised method

Abstract

Direct analysis of solids by graphite furnace atomic absorption spectrometry using a second surface atomizer

The direct graphite furnace atomic absorption spectrometric analysis of solids using the second surface atomizer has been investigated. The atomizer features a gas-cooled Ta insert within the graphite furnace onto which the analyte can be condensed, after which atomization is performed by raising the furnace to a higher temperature and shutting off the coolant gas. The analyses were conducted on standard reference material fly ash, river sediment, and citrus leaves, in addition to filter paper samples. All analyses were conducted without sample pretreatment or use of matrix modifiers. Quantitation was done by using simple aqueous standards. By use of peak heights, the recoveries varied from 81% to 127%, although several determinations were within the certified concentration range. The procedures typically gave low background absorbances and peak shapes that were relatively independent of the original sample matrix.

A pyrolysis—mass spectrometry study of the role of organic releasing agents in graphite furnace atomic absorption spectroscopic analysis of seawater

Commercial filament-type pyrolysis apparatus (CDS 100–382) directly interfaced to a Finnigan 4000 mass spectrometer (INCOS data system) was used to investigate processes relevant to the direct graphite furnace atomic absorption spectroscopic determination of trace metals in seawater with the aid of organic “releasing agents”. The temperature of the pyrolyzer filament was programmed so the pyrolysis—mass spectrometry experiments would be analogous to the GFAAS operation. Rapid mass spectrometer scans ( < 0.5 s) allowed temporal resolution of pyrolysis reactions. Chemical ionization (Ar, He, i-butane; positive, negative) and electron impact ionization were used. Systems studied included those relevant to the direct determination of Zn and Cd in seawater, using citric acid and EDTA as releasing agents. Analytical sensitivities for determinations of trace metals in seawater by pyrolysis—mass spectrometry were assessed with the aid of GFAAS.

Organic matrix modifiers for direct graphite furnace atomic absorption determination of cadmium in sea water

Organic matrix modifiers for direct graphite furnace atomic absorption determination of cadmium in sea water