Zeeman Graphite Furnace Atomic Absorption Spectrometry Research Articles

Transformation of tributyltin in zebrafish eleutheroembryos (Danio rerio).

Organotin compounds are highly versatile group of organometallic chemicals used in industrial and agricultural applications. Their endocrine-disrupting effects are well known and their extensive uses as biocide materials, e.g., in antifouling paints, for many years have led to serious environmental problems. So far, attention has mainly been given to tributyltin pollution in water, sediments, and marine organisms because of its highly toxic effects and high accumulation levels at very low concentrations. In this study, we will focus on the conversion of tributyltin after it is absorbed by zebrafish eleutheroembryos, presented here as an alternative model to adult fish for describing bioconcentration. A simplified analytical extraction procedure based on the use of an assisted ultrasonic probe and derivatization by ethylation, followed by gas chromatography with a flame photometric detector (GC-FPD) is proposed. This classical methodology for organotin determination has been validated by inductively coupled plasma mass spectrometry (ICP-MS) and Zeeman graphite furnace atomic absorption spectrometry (ZGF-AAS) in terms of total tin content. The speciation analysis results show that zebrafish eleutheroembryos absorb high amounts of tributyltin and convert it into monobutyltin and likely in inorganic tin.

Aluminum determination in biological fluids and dialysis concentrates via chelation with 8-hydroxyquinoline and solvent extraction/fluorimetry

We describe a simple, rapid, and sensitive fluorescence method for measurement of aluminum (Al) in human biological fluids, in dialysis solutions, and in tap water, which uses 8-hydroxyquinoline for ion chelation. The fluorescence intensity of the toluene-extracted metal chelate (excitation wavelength, 380 nm; emission wavelength, 504 nm) remains unchanged for over 48 h at room temperature. Fluorescence intensity is a linear function of the concentration of Al in the 2–1000 μg/L range with detection limits of 0.7–2 μg/L. A large excess of other ions normally found in biological fluids does not interfere in Al determination. The method developed was successfully used in assaying Al in serum and urine of reference subjects, in serum samples from patients undergoing long-term dialysis, and in dialysis solutions. Al concentrations, measured by this fluorimetric procedure, were compared with those obtained by Zeeman graphite-furnace atomic absorption spectrometry. A correlation coefficient of 0.98 was obtained. The proposed method could be used for routine analysis in clinical laboratories for accurate determination of aluminum in aqueous or biological fluids.

Evaluation of a tunable bandpass reaction cell for an inductively coupled plasma mass spectrometer for the determination of chromium and vanadium in serum and urine

A Dynamic Reaction Cell™ inductively coupled argon plasma mass spectrometer (DRC-ICP-MS) was evaluated for the determination of chromium and vanadium in serum and urine. Reaction cell conditions were evaluated for the elimination of ArC + and ClOH + interferences on chromium at mass 52 and OCl + on vanadium at mass 51. A diluent containing only 1% nitric acid and internal standards (Y and Ga) was used to prepare serum and urine for analysis. Instrument response calibration was achieved by using aqueous acidic standards spiked into pooled sera or urine matrices. The slopes of the calibration curves prepared in urine and serum matrices were nearly identical. On average, chromium detection limits are 2.5 times lower using the DRC than Zeeman graphite furnace atomic absorption spectrometry (ZGFAAS). Vanadium detection limits are approximately 50 times lower. Average detection limits achieved with DRC-ICP-MS are 0.075 μg Cr/l and 0.028 μg V/l. Average results for the analysis of National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1598 Bovine Serum (attained over 22 days) are: 0.14 μg Cr/l and 0.068 μg V/l. The reference concentrations for vanadium and chromium in NIST SRM 1598 are (0.06) μg V/l and 0.14±0.08 μg Cr/l, respectively. Results for chromium and vanadium determinations on ICP-MS survey samples from the Toxocologie du Quebec are equivalent to those reported by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for the same survey samples.

The determination of selenium in serum and urine by inductively coupled plasma mass spectrometry: comparison with Zeeman graphite furnace atomic absorption spectrometry

An inductively Coupled Plasma Mass Spectrometric (ICPMS) method for the determination of selenium in both serum and urine is described. 78Se is used analytically in spite of 38Ar40Ar isobaric interference at mass 78. Initially 82Se was monitored but, limited isotope abundance and therefore limited detection capability for urine selenium precluded continued use. An ethanol–Triton X-100-nitric acid diluent was used to dilute serum and urine and enhance selenium ionization so that both serum and urine can be analyzed with the same calibration curve. Results derived by the ICPMS method were compared with Zeeman Graphite Furnace Atomic Absorption Spectrometry (ZGFAAS) using nickel as the matrix modifier. Detection limits for ZGFAAS and ICPMS using mass 78 are 2.9 and 0.25 μg/l, respectively. ICPMS and ZGFAAS instrument responses were recorded for additions of inorganic selenium, trimethylselenonium iodide, seleno-dl-methionine, and seleno-dl-cystine to urine and serum. ICPMS slopes for all compounds added to urine and serum were found to be nearly identical. ZGFAAS response for each compound was more variable than ICPMS. ZGFAAS response for trimethylselenonium iodide was approximately 3-fold lower than for the other compounds. ZGFAAS regression slopes and correlation coefficients were 0.72 and 0.8139 for reference urine samples. ICPMS regression slope and correlation coefficient vs. the reference target values were 0.95 and 0.9700 for the same urines. Regressions slopes and correlation coefficients for reference sera were 1.01 and 0.9912 for ICPMS and 1.12 and 0.9648 for ZGFAAS. We conclude that ICPMS produced more accurate results than ZGFAAS for selenium in serum and urine.

Fluorometric determination of serum and urinary aluminium with 8-quinolinol by kinetic-differentiation-mode micellar chromatography

A new fluorometric method has been developed for the determination of aluminium with 8-quinolinol by kinetic-differentiation-mode micellar chromatography. The proposed method enabled the determination of aluminium down to 1 μg/l in human serum and urine without preliminary deproteinization. The most remarkable point of this method is that only aluminium ion selectively responds among metal ions. The complex formation of aluminium in serum with 8-quinolinol was completed within a few minutes at room temperature. The serum matrix and aluminium chelate were separated on a reversed-phase column with an eluent containing acetonitrile, sodium dodecylsulfate, and Triton X-100, and aluminium chelate was detected at Ex 370 nm, Em 504 nm. The values obtained by this method were in good agreement with those of Zeeman graphite-furnace atomic absorption spectrometry. The proposed method will provide a simple and rapid technique for the determination aluminium in medical fields.

Newton Method of Successive Approximations for the Linearization of the Calibration Curves of Chromium, Copper, Lead, Manganese, Silver, and Thallium in Zeeman Graphite Furnace Atomic Absorption Spectrometry

A new approach for the linearization of calibration curves in graphite furnace atomic absorption spectrometry (GFAAS) with Zeeman background correction was tested experimentally in an intermediate concentration region before rollover. The computational procedure employed the Newton method of successive approximations and was based on the theoretical model of L'vov et al. The calculations were based on three measured parameters: the rollover absorbance, Ar; the sensitivity ratio at the rollover point, R′; and the original background-corrected peak absorbances Az. This computational procedure generated corrected normalized integrated absorbance values A0,n with the slope identical to the slope of the original linear part of the calibration curve. The new computational procedure was employed for the linearization of calibration curves of chromium, copper, lead, manganese, silver, and thallium in Zeeman GFAAS under stabilized temperature platform furnace (STPF) conditions. Overall, the new computational procedure was able to extend the linear range of the calibration curves by a factor of 2–3 for the tested elements.

Newton approximation method for linearization of calibration curves in Zeeman graphite furnace atomic absorption spectrometry

An algorithm previously developed by L'vov et al. [ Spectrochim. Acta 47B, 889 (1992), and Spectrochim. Acta 47B, 1187 (1992)] was extended to allow for improved linearization of the upper end of the calibration curves of Zeeman graphite furnace atomic absorption spectrometry (GFAAS). The theoretical model of L'vov et al. described the effect of stray light on the calibration curves, and was based on three parameters: the rollover absorbance, A r, the limiting absorbance, A lim, and the Zeeman sensitivity ratio, R. Their theoretical treatment did not have an exact mathematical solution; rather, they used a simplifying assumption that the Zeeman sensitivity ratio had unity value and this made it possible to linearize the calibration curves. An extension of the algorithms of L'vov et al. is described here, which used Newton's method of successive approximations to approach a solution to the theoretical expression of L'vov et al., while still allowing the sensitivity ratio at the rollover point, R', to be taken into account along with the rollover absorbance. Both the extended algorithm and the algorithm of L'vov et al. were used for the linearization of the calibration curves of copper, silver, manganese, bismuth and thallium in Zeeman GFAAS. The characteristic mass values [cf. Microchem. J. 48, 278 (1993)] obtained from the linearized parts of the calibration curves of both models were compared to test the validity of each algorithm. The experimental and theoretical values of the characteristic masses of both models nearly coincided (±7%) for elements with R ⩾ 0.6. However, for copper ( R ⩽ 0.5) the differences between the theoretical and experimental characteristic masses values were 2% and 25% for the extended algorithm and that of L'vov et al., respectively. Overall, these results indicated the general validity of the L'vov et al. linearization algorithm and assumptions, but the case of copper demonstrated some limitations of the L'vov algorithm that could be mitigated by the extension described here.

Blood Lead Determination by Zeeman Graphite-Furnace Atomic Absorption Spectrometry

s Third International Congress of Therapeutic Drug Monitoring and Clinical Toxicology: PDF Only

Extension of the dynamic range in Zeeman graphite furnace atomic absorption spectrometry

In order to extend the dynamic range of Zeeman graphite furnace atomic absorption spectrometry (GFAAS), we propose a method to restore the dip formed in the region of the absorption pulse maximum and resulting from the roll-over of the calibration curve. A previously proposed model (B. V. L'vov et al., Spectrochim. Acta 47B, 1187 (1992)) for the ascending part of the Zeeman calibration curve and one developed on the same basis for the descending part of the curve has made it possible to linearize the calibration graph over the entire range of absorption variation in terms of two parameters: roll-over absorbance, A r, and Zeeman sensitivity ratio, R. The use of the dip extends the dynamic range, on average, by an order of magnitude compared to a range restricted by the roll-over point. This makes the full dynamic range of Zeeman GFAAS 3–4 orders of magnitude higher than the characteristic mass, m 0. The method has been tested on three elements (Be, Bi and Cd) having different Á r and R parameters. The measurement error in the determination of analyte mass for large signals in the dip region does not exceed that for signals of average magnitude. The correction of spectral interference in the dip region is approximately equivalent to the continuum background correction with a single light source.

Improved sample preparation for accurate determination of low concentrations of lead in whole blood by graphite furnace analysis

The effect of low concentrations of lead on pre- and post-natal growth and development is a current concern. We describe a simple method of sample preparation for direct determination of lead in whole blood by Zeeman graphite-furnace atomic absorption spectrometry. This procedure improves analytical precision and accuracy of lead determinations at low concentrations as compared with published furnace data. At blood lead concentrations of 0.25, 1.98, and 3.76 mumol/L, within-run CVs were 3.2%, 1.8%, and 1.4% respectively; between-run CVs were 7.3%, 2.9%, and 2.2%. Accuracy, as demonstrated by analytical recovery, ranged from 99% to 102%. Our reproducibility/accuracy score in the 1989 Quebec interlaboratory comparison program was 96% compared with the target, second best of 66 participating laboratories.

Direct determination of atmospheric lead by Zeeman solid sampling graphite furnace atomic absorption spectrometry (GFAAS)

Atmospheric lead was collected by membrane filters using two low volume air samplers at Julich, Stolberg, and Wetzlar, Federal Republic of Germany. Sampling times varied from 2 to 8 h. After sampling, each filter was subsampled in two cross-sections using a clean stainless steel punch (diameter 5 mm). The lead content of each subsample disc was determined directly by Zeeman GFAAS, calibrated with aqueous standard solutions and supported by solid reference materials. The distribution of lead between the subsamples was generally homogeneous, with standard deviations ranging from 11 to 37%, but typically <15% for samples with 8 h sampling time. The analysis of each filter usually took about 30 min. The differences in air quality between the three sampling locations, as measured by the lead concentrations, are discussed. In general, Stolberg appears to have the highest lead concentrations. The mass particle-size distribution of lead in the aerosol samples collected by membrane filters using a cascade impactor at Stolberg was also investigated with the same analytical technique. Using graphite platform boats as direct samplers, it is possible for the dry deposition flux of lead to be estimated. This provides a quick means of assessing the levels of lead pollution in the atmospheric environment. With lead concentrations measured in parallel, the dry deposition velocities of lead can be estimated under various meteorological conditions. Application of similar sampling and analytical techniques to other atmospheric trace metals may be possible.

Determination of traces of silver in copper by direct Zeeman graphite furnace atomic absorption spectrometry

A method was developed to determine traces of silver in copper by direct Zeeman graphite furnace atomic absorption spectrometry (ZAAS) on solid samples. The system is calibrated using quantitatively doped copper, whose blank silver content is determined using an iterative process. The method has been applied to the analysis of several candidate reference materials. Relative standard deviations of 2 to 5% are obtained in the range 1 to 12 μg·g−1. Furthermore, it was also applied to assess the homogeneity of a neutron dosimetry candidate reference material.

Determination of silver in biological samples using graphite furnace atomic absorption spectrometry based on Zeeman effect background correction and matrix modification

A method for the determination of silver in human body fluids and biological material is described. The silver in an acid digest of biological samples and diluted body fluids is quantified using Zeeman graphite furnace atomic absorption spectrometry (ZGFAAS). The effects of NH4H2PO4 as matrix modifier and standard addition are discussed. Atomization from the graphite tube wall and from the pyrolytical tube with platform is also discussed and the peak height and the peak area are compared. The best results were achieved by using matrix modification, stabilized temperature platform furnace, integrated absorbance and standard addition technique. The calibration was linear up to 15 micrograms X L-1; the between-run precision was 5.9% at 40 micrograms X kg-1 of silver.

Determination of silver in sea water by coprecipitation with cobalt pyrrolidinedithiocarbamate and Zeeman graphite-furnace atomic absorption spectrometry

A preconcentration technique is described for silver, which allows the precise and accurate determination of silver in sea water at nanogram per liter levels. Silver is co-precipitated with cobalt(II) pyrrolidinedithiocarbamate from 200-ml samples. The precipitate is dissolved in concentrated nitric acid and silver is quantified by Zeeman graphite-furnace atomic absorption spectrometry, with acid phosphate matrix modification. The detection limit is 0.1 ng l −. The method is simple and rapid, and also allows the simultaneous extraction of lead, copper, cadmium, and nickel.