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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↗

PubMed1989

Determination of molybdenum in plasma using graphite furnace atomic absorption spectrometry.

A sensitive method is described for the determination of Mo in plasma or serum by graphite furnace atomic absorption spectrometry. The method involves extraction of the metal as the 8-hydroxyquinoline complex and is free of the interference effects that prevent the direct analysis of plasma for Mo. Recoveries of internal standards were excellent and results from the analysis of a National Institute of Standards and Technology Standard Reference Material were in good agreement with certified values. The sensitivity of the method, based on the analysis of 1 ml of plasma, is ca. 3 ng ml-1.

Animals↗

PubMed1990

Evaluation of biological sample mineralisation methods for the determination of fluorine by graphite furnace molecular absorption spectrometry.

Various mineralisation methods were evaluated as means of treating different liquid and solid biological samples for the determination of fluorine by the formation of aluminium monofluoride in an electrothermal graphite furnace and molecular absorption spectrometry (AIF-MAS). Simple sample dilution and the use of 0.01 M Al3+ + 0.01 M Sr2+ solution as a matrix modifier are sufficient to determine the fluorine content in most liquid samples, although some require the addition of 0.3 M ammonium nitrate to the matrix modifier solution in order to diminish background absorbance. In solid samples, treatment methods routinely used with fluoride ion-selective electrodes such as microdiffusion, furnace ashing - microdiffusion and oxygen flask combustion, were tested for compatibility with AIF-MAS. The results were compared with those obtained with a fluoride ion-selective electrode. The proposed mineralisation methods were checked for applicability to different plants, foodstuffs and other biological materials. Some of the methods gave an over-all precision of better than 10%, which is often acceptable, and all methods gave recoveries above 80%. Differences between labile + ionic fluoride and total fluorine can be established by sample treatment.

Evaluation Studies as Topic↗

PubMed1990

Determination of trace amount of cobalt in feed grains and forages by solvent extraction and graphite furnace atomic absorption spectrometry.

A method is described for the determination of trace amounts of cobalt in feed grains and forages with a detection limit of 1 ng g-1. Samples are ashed in a muffle furnace and complexed with 2-nitroso-1-naphthol. Following solvent extraction, cobalt is determined using graphite furnace atomic absorption spectrometry. The assay can be carried out in a normal analytical laboratory without the need for special "clean" rooms. Reagents have been selected to keep reagent blank values at low levels, and heptan-2-one is used as extracting solvent to avoid problems with evaporation. The assay has been used for diagnostic purposes and to formulate special low cobalt diets for sheep for experimental purposes.

Animal Feed↗

PubMedDate not supplied

Determination of cadmium and lead in foods by graphite furnace atomic absorption spectrometry with Zeeman background correction: test with certified reference materials.

Two methods for the determination of cadmium and lead based on graphite furnace atomic absorption spectrometry (GFAAS) with Zeeman background correction are described. The main difference between the methods is the method of sample destruction, bomb digestion versus dry ashing. The precision and accuracy of the methods has been tested by analysing 16 different reference materials, with cadmium concentrations varying from 2.9 micrograms/kg to 2.7 mg/kg and lead concentrations from 44 micrograms/kg to 13.5 mg/kg. The methods produced results which differ, with a few exceptions, less than 10% from the certified contents, with relative standard deviations of around 5%. The methods are not difficult to carry out, are not very laborious and without modifications are applicable to a large variety of products. The sample solutions obtained can also be used for the determination of other elements, e.g. Al, Cr, Cu, Hg, Mn, Ni and Zn. The detection limits, for test portions of 1 and 5 g (wet products) are 0.5-1 microgram/kg for cadmium and 5-20 micrograms/kg for lead.

Animals↗

PubMed1986

Determination of ultra trace amounts of cobalt in fish by graphite furnace Zeeman effect atomic absorption spectrometry.

A method is described for determining stable cobalt concentrations in fish flesh and bone using polarized Zeeman effect graphite furnace atomic absorption spectrometry (ZAAS). Cobalt analysis on freshwater fish flesh samples (10 g dry weight) required predigestion and wet-ashing at 70-80 degrees C. Cobalt is chelated with ammonium pyrrolidine dithiocarbamate (APDC) extracted with methyl isobutyl ketone (MIBK) and analysed by ZAAS. The mean cobalt content calculated from the standard additions method using three replicate fish flesh samples was 4.23 +/- 1.0 microgram Co. Kg-1 (dry weight). Analyses were also carried out on flesh and bone samples from similar sized fish, of the same species, taken from three area lakes.

Animals↗

PubMed1991

Graphitized carbon black in quartz tubes for the sampling of indoor air nicotine and analysis by microwave thermal desorption-capillary gas chromatography.

Nicotine in a smoky indoor air environment can be determined using graphitized carbon black as a solid sorbent in quartz tubes. The temperature stability, high purity, and heat absorption characteristics of the sorbent, as well as the permeability of the quartz tubes to microwaves, enable the thermal desorption by means of microwaves after active sampling. Permeation and dynamic dilution procedures for the generation of nicotine in the vapor phase at low and high concentrations are used to evaluate the performances of the sampler. Tube preparation is described and the microwave desorption temperature is measured. Breakthrough volume is determined to allow sampling at 0.1-1 L/min for definite periods of time. The procedure is tested for the determination of gas and paticulate phase nicotine in sidestream smoke produced in an experimental chamber.

Air Pollutants↗

PubMedDate not supplied

Determination of tin in biological materials by atomic-absorption spectrometry with a graphite furnace.

The determination of tin in the blood, liver, kidney, and spleen by atomic-absorption measurement using a graphite furnace was investigated. The presence of 20 micrograms/mL Fe(III) reduced absorbance of 0.2 microgram/mL Sn to 50%. To remove the interference of Fe(III), it was reduced to Fe(II) by 10% ascorbic acid, and Sn(IV) was extracted by methylisobutylketone (MIBK) without a chelating agent. This technique can be applied when 100 micrograms/mL Fe coexists with 0.2 microgram/mL Sn. Four methods for determination of tin in the blood were examined: (a) standard addition, (b) low-temperature ashing/MIBK extraction, (c) wet ashing/MIBK extraction, and (d) direct determination. The results of (a), (b), and (c) showed a high correlation (r greater than 0.86, n = 12), while the values obtained by (d) were scattered widely and showed little correlation with those determined by the other three methods. In methods (b) and (c), the detection limit was 10 ng/mL (0.2 ng Sn) without expansion mode, 2 ng/mL (0.04 ng Sn) with X 5 expansion mode, the recovery more than 90%, and the coefficient of variation 6.6% (n = 8). Method (c) was recommended for large sample sizes, and was also suitable for determination of tin in liver, kidney, and spleen, using 0.5%, instead of 10%, ascorbic acid.

Animals↗

PubMed1983

Microanalysis of platinum in biological media by graphite furnace atomic absorption spectroscopy.

An accurate method for the analysis of platinum in biological matrix is described. The method requires minimal sample handling and pretreatment prior to injection into the graphite furnace. It is reproducible, with average recovery of 97.7% platinum in biological matrix. The data presented also demonstrate that Fe in particular (also NaCl and HNO3) significantly depresses the atomic absorption signal of platinum. Standard addition calibration curves are therefore essential for determination of platinum in biological samples.

Humans↗

PubMed1991

Determination of dietary cadmium-induced metallothioneins in rabbit kidneys and cadmium in metallothioneins by anion-exchange high-performance liquid chromatography coupled with graphite furnace atomic absorption spectrometry.

A rapid method is described for the determination of dietary cadmium-induced metallothioneins (MTs) in rabbit kidneys by anion-exchange high-performance liquid chromatography. Rabbit kidney MT-I and MT-II were eluted at ca. 15.0 and 18.8 min, respectively, from a DEAE-5PW anion-exchange column with a Tris-HCl buffer (0.01-0.25 M, pH 8.6) and detected by ultraviolet absorbance at 254 nm. A standard calibration curve was constructed using purified standard MT isoforms, which demonstrated an excellent linear correlation between UV absorbance peak heights and the amounts of MT isoforms. Feeding a dose of cadmium for some days resulted in an increase in MT concentrations in rabbit kidneys, but not in the livers. The cadmium concentrations in MT-I and MT-II elutions were determined by graphite furnace atomic absorption spectrometry. MT-I and MT-II showed some differences associated with the oral intake of cadmium. Dietary cadmium also caused zinc to accumulate in kidneys to some extent. The effects of dietary oleic acid on the synthesis of MTs were also studied. Based on the method of standard additions, the recovery of MTs exceeded 93% and replicated injection of samples yielded a relative standard deviation of 2.4% at an MT level of 280 micrograms/g.

Animals↗

PubMed1991

Determination of Cd, Cr, Cu, Pb and Zn in human semen by graphite furnace atomic absorption spectrometry after microwave sample dissolution.

Human semen samples were analyzed by graphite furnace atomic absorption spectrometry, using L'vov platforms and the method of standard additions, to determine their Cd, Cr, Cu, Pb and Zn content. The samples were analyzed directly and after conventional and microwave wet acid dissolution. Matrix modification, using magnesium and palladium nitrates and ammonium biphosphate solutions, was evaluated for the analysis of the microwave-digested samples. The best results were obtained for Cr, Cu and Zn using Pd(NO3)2, and a mixture of Mg(NO3)2 and Pd(NO3)2 solutions. The direct analysis of water-diluted semen produced inaccurate results with unacceptably high standard deviations. The results obtained for the microwave-dissolved samples showed relative standard deviation values within the range 0.63-8.4%. The analysis of spiked semen solutions showed recoveries of the added analytes ranging from 96 to 104%. The accuracy of the measurements was checked against the NIST 1,577a, bovine liver, standard reference material. Sample dissolution time was drastically reduced from 3-4 hours, using the conventional method, to approximately 8 minutes using the microwave-assisted wet acid digestion procedure.

Cadmium↗