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PubMed1991

Graphite furnace atomic absorption spectrometric determination of blood lead with palladium modification.

In this work we present a graphite furnace atomic absorption spectrometric method for blood lead using palladium as a chemical modifier. Whole blood was diluted 10- fold with a 0.1% v/v triton X-100 solution; 10 microL of this solution and 10 microL of the palladium-based modifier (2 mg Pd/L, 2% w/v citric acid and 0.01 M nitric acid) were injected onto the L'vov platform by using the alternate volume mode. The following furnace operating parameters were used: (a) drying steps, 120 degrees C for 10s and 250 degrees C for 30s; (b) pyrolysis steps, 800 degrees C for 45s (with oxygen) and 1100 degrees C for 25s; (c) atomization, 1600 degrees C for 3s; (d) clean out, 2700 degrees C for 4s. Accuracy was tested by using (i) a NIST standard (SRM-909) and the Behring Control Blood for Metal 1 (OSSD 21) with lead concentrations of 23.7 +/- 2.1 micrograms/L (found: 21.2 +/- 0.7 micrograms/L) and 413 +/- 51 micrograms/L (found: 407 +/- 6 micrograms/L), respectively; (ii) recovery studies (ca. 100 +/- 1%), and (iii) a reported method (mean relative error: 5.1%). Approximate standard deviations of 0.3 (within-run) and 0.7 (between-runs) micrograms Pb/L were found in the precision study. The detection limit (3 sigma) and the characteristic mass (for a 10- microL injection volume) were 0.1 micrograms Pb/L and 15 pg/0.0044 A.s, respectively. The proposed method was used to establish the lead levels of patients with renal insufficiency; a mean concentration (+/- SD) of 59 +/- 39 micrograms Pb/L (range: 12- 160 micrograms Pb/L) was found. The method was interference-free, reliable and reproducible.

Graphite↗

PubMed1975

Ultramicro analysis for copper, cadmium, and zinc in human liver tissue by use of atomic absorption spectrophotometry and the heated graphite tube atomizer.

We describe a method of analysis for copper, cadmium, and zinc in a 15-mg (wet weight) sample of human liver by atomic absorption spectrophotometry. The sample is digested with nitric acid (1.0 mol/liter), evaporated, and dilute HNO3 (10 mmol/liter) added. The reconstituted acid mixture is injected into the graphite tube atomizer for analysis of Cu and Cd and aspirated into the air--acetylene flame for measurement of Zn. The absorbance for each metal is suppressed with increasing pH. NaNO3, KNO3, KCl, and NaCl (e.g.) quench the Cd absorbance in acid solutions that contain no protein, but not in the presence of protein. Metal ions added to the predigestion human liver sample at 10 percent and 100 percent of the intrinsic metal concentrations were, respectively, 93 percent and 90 percent accounted for analytically in the case of Cu, 98 percent and 102 percent for Zn, and 101 percent and 93 percent for Cd. Analysis of a National Bureau of Standards' Bovine Liver Standard Reference Material yielded results corresponding to 99 percent (Cu), 112 percent (Zn), and 91 percent (Cd) of the mean expected concentrations of these metals. The between-run coefficient of variation for the bovine liver material was 6 percent for Cu, 9 percent for Zn, and 10 percent for Cd. For 16 histologically normal samples of human liver, the mean values were: Cu, 26; Zn, 293; and Cd, 6.0 nanograms of metal per milligram dry weight, in agreement with values published previously. The method can be easily and reliably applied to small samples of liver obtained by closed-needle biopsy.

Animals↗

PubMed1975

Determination of serum copper by atomic absorption, with use of the graphite cuvette.

We have established and evaluated a flameless graphite cuvette method for copper in serum. This atomic absorption method provides substantial improvement in sensitivity, adequate accuracy, and acceptable precision, and little sample preparation is required before the analysis. Standard addition studies and measurements of National Bureau of Standards materials indicated that the proposed method is accurate, but that sample pH must be kept between 2 and 3 for high accuracy. Cations and anions that frequently are present in protein-containing samples do not interfere significantly. Sample cross contamination in the syringe must be carefully avoided. Finally, when results for more than 100 patients' sera by this method were compared to those obtained by flame atomic absorption for the same samples, no substantial bias or inaccuracies could be attributed to this new micro-scale method for serum copper. Hence, this method is ideally suited for use on pediatric patients.

Copper↗

PubMed1988

Aluminum determination in whole blood, dialysis solution, and tap water samples from Maracaibo dialysis units (Venezuela) by graphite furnace atomic absorption spectrometry.

Patients with chronic renal failure (CRF) on periodical hemodialysis may accumulate aluminum in tissues and show typical disorders such as dialysis encephalopathy, osteodystrophy, and microcytic anemia. Aluminum contamination of the water used to prepare the dialysis solution (dialysate) is one of the metal sources that may affect people under hemodialysis, especially in units in which untreated water is used. Graphite furnace atomic absorption spectrometric methods for aluminum determination in whole blood, dialysis solution, and tap water samples from CRF patients were developed, based upon the use of the same furnace temperature program. Samples were diluted 4-fold with 0.6% triton X-100 (whole blood) or with 0.01 mol/L nitric acid (dialysis solution and tap water) and analyzed by aqueous standard (blood and tap water) or matrix-matching standard (dialysis solution) calibration curves. The characteristic masses were 33.8, 11.3, and 19.5 pg Al/0.0044 A.s for whole blood, dialysate, and tap water, respectively. In the diluted solutions, the detection limits (2 sigma) for the described methods were 0.5 microgram/L Al (whole blood), 0.4 microgram/L Al (dialysate), and 0.4 microgram/L Al (tap water). The methods were applied to samples from several CRF patients under hemodialysis at Maracaibo University hospital. The data revealed extremely high aluminum levels, which corresponded to the symptoms of dialysis encephalopathy and/or osteodystrophy showed by some of them. The proposed methods are reliable and reproducible.

Aluminum↗

PubMed1977

[Determination of antimony from environmental air in the working area using flameless atomic absorption with a graphite furnace].

Particulates of antimony present in area of plants producing a catalyst containing iron an antimony have been determined. The environmental aereosol, filtered through micropore filters, is analyzed in the form of stabilized aqueous suspension by atomic adsorption flameless graphite furnace. The limit of air revealability permitted by the method is 0.2 mcg/m3. With the above mentioned revealability limit it is possible to perform very rapid drawings of environmental air, so that noxiouslity of even very short-time processing can be controlled.

Air Pollutants↗

PubMed1991

Chromium, lead and cadmium in Danish milk products and cheese determined by Zeeman graphite furnace atomic absorption spectrometry after direct injection or pressurized ashing.

A method for the direct determination of chromium in homogeneous samples of milk and milk products is described. Minimum sample handling and prevention of contamination was given priority. After injection of the sample into the graphite furnace, the sample was ashed in a stream of oxygen at 650 degrees C and then further ashed at 1,100 degrees C with argon as the purge gas. Zeeman background correction was used in the atomisation step at 2,300 degrees C. The detection limit was 0.7 ng/g. Direct detection of chromium in milk, using only argon as purge gas, was inferior. Non-homogeneous and solid samples, e.g. yoghurt with fruit jam and cheese, were ashed under pressure with nitric acid before analysis. The same analytical principle as used for chromium was also used for the analysis of lead and cadmium in the samples. Analytical quality control was performed for both methods and the results are reported. The results for lead, cadmium and chromium in Danish milk and milk products were in the parts per billion or parts per trillion range and compare well with literature data. The intake of lead, cadmium and chromium from milk and milk products is less than 4% of the total Danish dietary intake of these elements. It is concluded that the contribution from milk and milk products to the total intake of lead and cadmium is toxicologically insignificant and that milk and milk products are only a minor source of the essential element chromium.

Animals↗

PubMed1992

Serum nickel levels of diabetic patients and healthy controls by AAS with a graphite furnace.

In this study, serum nickel levels of diabetic patients and healthy controls were determined by AAS with a graphite furnace. The serum nickel concentrations were found to be 1.15 +/- 1.89 micrograms/L in healthy controls and 0.82 +/- 0.74 microgram/L in diabetics. There was, however, no statistically significant difference between the two groups (p = 0.13). The relationship of nickel levels to diabetes type and duration, diabetic complications and treatment, sex, age, and heredity was investigated. However, again no significant differences were found, nor was there any correlation between serum nickel levels and blood sugar, HBa1c, fructosamine, sialic acid levels, and age.

Adult↗

PubMedDate not supplied

Physiological chromium determination in serum by Zeeman graphite furnace atomic absorption spectrometry. A serious challenge.

Several authors have already underlined chromium implication in glucose and lipids metabolism of humans. In this field, physiological chromium determination in serum could be helpful, but the discrepancies reported in numerous papers are confusing. Here we report some results obtained by Zeeman correction Graphite Furnace Atomic Absorption Spectrometry. This technique includes a dilution of serum with 12.5 mM ultrapure nitric acid and 0.25% Triton X-100 (final concentrations). Some main features can be outlined: (1) the contamination constitutes a serious drawback and (2) the sensitivity of the technique is critical (characteristic mass found: 1.76 pg/0.0044 A.s). Our results obtained from 27 healthy subjects (2.01 +/- 0.77 nmol/L) agree with most recent studies and indicate that serum chromium level does not seem to be sex-related.

Chromium↗

PubMed1989

Determination of lead in blood by graphite furnace atomic absorption spectrometry--a critique.

Graphite furnace atomic absorption spectrometry (GFAAS) is increasingly becoming the method of choice for the determination of Pb in blood. The major GFAAS methods that have been published to date include: (i) direct introduction of the sample into the furnace; (ii) dilution with water, Triton X-100 or acid; (iii) deproteinization with nitric acid; (iv) matrix modification; and (v) solvent extraction. This review focuses on the difficulties associated with each of these methods, and highlights recent attempts to overcome matrix interferences and improve the accuracy and precision of Pb determination in blood using modern furnace technology, especially the stabilized temperature platform furnace.

Humans↗

PubMed1989

Graphite-furnace atomic absorption spectrometric determination of lead, cadmium, cobalt and nickel in infant formulas and evaporated milks after nitric-perchloric acid digestion and coprecipitation with ammonium pyrrolidine dithiocarbamate.

A graphite-furnace atomic absorption method, developed for lead and cadmium, was modified to enable simultaneous determination of lead, cadmium, cobalt and nickel in infant formulas and evaporated milks. The method was assessed on the basis of analytical quality assurance results during routine analysis of samples. Detection limits (ng g-1 based on 10 g sample size for ready-to-use formulas) were 0.04-0.21 for lead, 0.004-0.015 for cadmium, 0.04-0.2 for cobalt and 0.06-0.26 for nickel. Within-series repeatability and day-to-day reproducibility (among series) coefficients of variation (CVs) were, respectively, 11.7 and 16% for lead, 2.5 and 7.5% for cadmium, 7.2 and 18.8%for cobalt, and 8.1 and 8.6% for nickel at respective concentrations of 1.89, 0.40, 1.25 and 11.8 ng g-1.

Animals↗

PubMed1989

Determination of nickel in urine with graphite furnace AAS using Zeeman correction.

We have developed a rapid and direct method for determining urine nickel. The urine specimen is diluted (1 + 1) with 2.0% v/v nitric acid and 0.001% v/v Triton X-100 and absorbance measurements are made with Zeeman-effect graphite furnace atomic absorption. The method is sensitive enough to be used to evaluate "normal" subjects for baseline studies or to evaluate environmental or other nonoccupational exposure to nickel. The characteristic mass (pg/0.0044A.s) is 26 pg, which is comparable to that obtained for aqueous solutions. The observed absorbance is linear up to about 100 micrograms l-1, after which the calibration curve departs from linearity. Procedures are described to rigorously exclude nickel contamination. We evaluated precision and accuracy with a U.S. National Bureau of Standards urine reference material. SRM 2670, with an informational nickel value of 70 micrograms l-1, and with a multielement water reference material, SRM 1643b, with a certified nickel value of 49 ng g-1. Within- and among-run standard deviations for SRM 2670 were calculated to be 9.0 and 2.45 micrograms l-1, respectively, and 2.1 and 1.1 micrograms l-1 for SRM 1643b. The detection limit, calculated as 3 SD of a "low" concentration urine, is about 1.1 micrograms l-1. The proposed method was applied to the determination of nickel in urine of 258 workers in a magnet manufacturing plant, and the data obtained support the usefulness of urine nickel for biological monitoring.

Environmental Exposure↗

PubMed1988

A high-performance liquid chromatographic assay for reduced and oxidised glutathione in embryonic, neonatal, and adult tissues using a porous graphite electrochemical detector.

A high-performance liquid chromatographic (HPLC) assay employing a porous graphite electrochemical (EC) detector is described for the simultaneous quantification of reduced glutathione (GSH) and oxidised glutathione (GSSG) in embryonic, neonatal, and adult tissues. Samples were prepared by homogenization in 5% trichloracetic acid, centrifugation, filtration of the supernatant, and injection into the HPLC. Separation was achieved isocratically within 16 min on a 15 cm reversed-phase C18 analytical column with a particle size of 5 micron using an inexpensive mobile phase containing 2-propanol and water (2.8:100) with camphorsulfonic acid and phosphoric acid. The respective limits of detection for GSH and GSSG were 1.5 and 3 ng with a 6 microliter sample using a 3:1 signal to noise ratio. In addition to routine samples, the assay was sufficiently sensitive to detect picomole quantities of GSH and GSSG in small samples, such as a single mouse embryo, gestational day 9, weighing approximately 1 mg. The advantages and disadvantages of the method are compared with other assays for GSH and GSSG published in the literature.

Animals↗

PubMed1990

Determination of lithium in rat brain regions and synaptosomes by graphite furnace atomic absorption spectrophotometry.

A graphite furnace atomic absorption spectrophotometric method for the analysis of very low concentrations of lithium in brain tissue and subcellular fractions is described. The method has a picogram sensitivity and shows a precision value of 10.1% expressed as the per cent variation coefficient for the tissue analysis of the metal. Lithium concentration in eight regions of the rat brain and regional synaptosomal lithium contents were analyzed with the method described. Results from these determinations show that lithium is heterogeneously distributed among rat brain regions 24 hr after a single s.c. lithium administration; hypothalamus, corpus striatum and midbrain were the regions with the highest lithium accumulation. Lithium is homogeneously concentrated in the synaptosomes obtained from rat brain regions. The method proposed may be considered adequate for trace lithium analysis in pharmacological studies of the metal.

Animals↗

PubMed1985

An amperometric glucose sensor made by modification of a graphite electrode surface with immobilized glucose oxidase and adsorbed mediator.

A membrane-free glucose sensor was made by covalent immobilization of glucose oxidase on graphite followed by adsorption of N-methyl-phenazinium ion (PMS+). The mediator was found to be necessary for the electron transfer between the enzyme and the electrode. beta-D-glucose was determined amperometrically at an applied potential of +50 mV vs SCE. The current was independent of the rotational speed which indicates a kinetically controlled response. The response was strictly linear from the detection limit, 0.5, to 150 microM and usable up to about 2 mM beta-D-glucose. The immobilized enzyme was stable over several months but the mediator had to be renewed daily.

Electrodes↗

PubMed1992

Improved high-performance liquid chromatographic procedure for the determination of lasalocid in chicken tissues and egg using polymeric and porous graphitic carbon columns.

A high-performance liquid chromatographic (HPLC) method for the determination of the ionophore coccidiostat lasalocid in poultry muscle and eggs was developed. The drug was extracted from tissue with acetonitrile. The extract was partitioned between saturated salt and carbon tetrachloride and the organic layer evaporated to dryness. Clean-up was by solid-phase extraction on a silica column. HPLC analysis was carried out on either a polymeric PLRP-S or a porous graphitic carbon Hypercarb column with a basic mobile phase and fluorescence detection with excitation at 310 nm and emission at 420-430 nm. Average recoveries from poultry muscle at the 0.002, 0.010 and 0.050 mg kg-1 levels were 65.7, 72.0 and 77.9%, respectively. Average recoveries from egg at the 0.010 and 0.100 mg kg-1 levels were 76.2 and 76.4%, respectively.

Animals↗

PubMed1989

Continuum source atomic absorption spectrometry in a graphite furnace with photodiode array detection.

A graphite furnace continuum source atomic absorption spectrometer using a photodiode array detector is described that provides high-resolution wavelength versus absorbance spectra over a 2.5-nm range for a single atomization step. The multiwavelength detection power allows the simultaneous determination of several elements, reduces problems caused by spectral interferences, and automatically corrects for nonzero background absorbance. Each spectrum is acquired in 0.33 s, and several successive spectra can be obtained during a single run. Three-dimensional wavelength-absorbance-furnace temperature spectra can be obtained by using ramped heating steps to provide a rough separation of elements in a mixture. Limits of detection calculated for 19 elements range from 0.1 pg for magnesium to 700 pg for arsenic. The sampling precision was found to be better than 10% relative standard deviation in all cases, with the precision for a single atomization being greatly increased when multiple absorption lines for a single element are observed in the spectrum. The error found for the measurement of the iron concentration in an NBS standard bronze was 8.5%, with the calculated concentration agreeing with the certified concentration within 95% confidence limits.

Metals↗

PubMed1989

Direct determination of iron in urine and serum using graphite furnace atomic absorption spectrometry.

A simple, rapid and low-cost method for the routine determination of iron in urine and serum using graphite furnace atomic absorption spectrometry is described which may provide an alternative to the more widespread automated spectrophotometric methods. The urine and serum samples were simply diluted with water prior to analysis. Matrix modification was found to be redundant. The standard additions technique or the use of matrix matched standards (addition calibration) was found to be unnecessary and, therefore, the calibration was performed using aqueous standards. For serum analysis the degree of dilution could be reduced by using the less sensitive 302.0-nm resonance line, yielding more precise determinations, and for urine analysis, interferences were eliminated by means of a L'vov platform. The interferences that exist in the presence of nitric acid are also discussed. Finally, the presence of background absorption was investigated by means of Zeeman effect atomic absorption.

Humans↗

PubMed1989

Direct determination of cadmium in urine using graphite furnace atomic absorption spectrometry with Zeeman-effect background correction.

A procedure is described for the direct determination of cadmium in human urine using graphite furnace atomic absorption spectrometry with Zeeman-effect background correction. Except for a straightforward 1 + 1 V/V dilution of samples with 1.5% nitric acid, no matrix modifier or sample pre-treatment was necessary, thus reducing the risk of contamination. The concentration of cadmium in urine was evaluated directly from a calibration graph prepared using a metal-spiked human urine pool. In this way the time-consuming method of standard additions was avoided, permitting an increased sample throughput (120-150 samples per day; 90 s per analysis) with minimal attention of the analyst. In routine use, the precision (both within day and day to day) and limit of detection were of the order of less than 10% and 0.05 micrograms l-1 of Cd, respectively. The method is suitable for the biological monitoring of cadmium in the general population or in occupationally exposed persons.

Cadmium↗