Atomization-atomic Absorption Spectrometry Research Articles

Toxicological analysis of Pb and Cd by ET AAS in local anaesthetics for teething (teething gels) based on herbs available in Polish pharmacies

Studies related to the toxicological analyses of metallic impurities in pharmaceuticals (drugs) is an important issue but there is a lack of refereed literature around the safety of teething remedies from herbal origin related to toxic metals impurities. In this article, the levels of Pb and Cd were measured in samples of local anaesthetics for teething (gels) based on herbs. This article was motivated by the fact that Pb and Cd are relevant toxic metals that may cause an adverse effect in babies even at low levels. Additional justifications were (1) the insufficient control of metal impurities in teething gels, (2) the lack of sufficient validation steps and (3) the inadequate sensitivity of applied analytical techniques. The aim of this article was a qualitative and quantitative analysis of Pb and Cd in the most popular and available local anaesthetic for teething (teething gels) based on herbs (n = 5) available in Poland. Metals were determined by ET AAS (electrothermal atomization atomic absorption spectrometry), after digestion in a microwave unit using concentrated nitric acid. It was observed that all samples contained Pb and Cd. The levels of Pb and Cd as impurities (independently of the producer and declared composition) are similar. The concentrations of Pb and Cd, at ng/day levels, to which the user is exposed at daily doses meet the standards of the directive ICH Q3D.

Content and Bioaccessibility of Aluminium in Duplicate Diets from Southern Spain

Aluminium is found naturally in foods and beverages, but levels increase notably during processing, packaging, storage, and cooking, as a consequence of its presence in food additives and the wide use of aluminium utensils and vessels. Dietary intake of Al was estimated in 2 population groups in southern Spain (families and university students) in a duplicate diet sampling study. Diets were sampled for 7 consecutive days, and Al was determined in acid-mineralized samples with electrothermal atomization-atomic absorption spectrometry (ETA-AAS). Mean values for Al intake were 2.93 and 1.01 mg/d in families and students, respectively, ranging from 0.12 to 10.00 mg/d. Assuming an average adult weight of 60 kg, the mean dietary exposures to aluminium were 0.34 and 0.12 mg/kg body weight/week in these groups, which amounted to 17% and 6% of the 2 mg/kg body weight estimated as the tolerable weekly intake by the Joint FAO/WHO Expert Committee on Food Additives. Bioaccessibility of dietary Al tested with in vitro studies ranged from 0.30 to 17.26% (absorbable fraction). The highest aluminium intakes were observed in subjects consuming diets with a low adherence to the Mediterranean diet, which were associated to high consumption of processed and canned food. On the contrary, subjects consuming diets with a high adherence to the Mediterranean diet patterns showed the lowest Al intakes. The present findings are useful for giving both a reliable estimate of total aluminium dietary intake and tolerable intake levels according to usual dietary habits.

Speciation analysis of thallium using electrothermal AAS following on-line pre-concentration in a microcolumn filled with multiwalled carbon nanotubes

The enrichment ability of carbon nanotubes (CNTs) was investigated and a new method established for the determination of trace thallium species in environmental samples using electrothermal atomization-atomic absorption spectrometry (ETAAS). The CNTs were employed as sorbent substrate in a continuous flow system coupled to ETAAS. Parameters influencing the recoveries of thallium were optimized. Under optimal conditions, the detection limit and precision of the method were 0.009 µg L−1 and 3.9%, respectively. The method was applied to the determination of thallium in real environmental samples and the recoveries were in the range from 96 to 100%. This system was able to separate thallium (I) from the matrix, which allowed its selective determination. The total thallium content was then determined by reducing Tl(III) with hydroxylamine. All these experimental results indicated that this new procedure can be applied to the determination of trace thallium in drinking water samples.

Direct determination of impurities in arsenic by atomic spectrometry

The present paper describes development of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Electrothermal Atomization-Atomic Absorption Spectrometry (ETA-AAS) for the direct determination of fifteen common metallic and semi-conducting elements in high purity arsenic without prior separation of the major matrix. With a view to improving determination of Cd in arsenic matrix and for providing independent check on determination of few representative elements such as Cu, Cr, Mn and Ni by ICP-AES method, ETA-AAS technique also has been developed for direct determination of these elements in arsenic matrix. A number of synthetic samples have been prepared and analysed by both the techniques to validate the analytical procedures adopted here.

Impairment of cell and plasma redox state in subjects professionally exposed to chromium.

Chromium (Cr) is widely used in chemical, tannery, building, and metal industries. More recently, it has been demonstrated that Cr induces oxidative stress in mouse brain. Nevertheless very few data exist on in vivo oxidative damage in humans exposed to Cr. Changes in antioxidant parameters both in plasma (acid ascorbic redox state and total antioxidant capacity) and in red blood cells (glutathione (GSH) redox state) of 40 subjects (age 37.65 +/- 7.46; M/F 20/20) professionally exposed to Cr who were recruited from metal, chemistry, and building industries were evaluated. We also evaluated the levels of lipoperoxidation (thiobarbituric acid-reactive material, TBA-RM) and thiol levels in plasma to assess the extent of oxidative stress state. To evaluate Cr exposure rate, we measured urinary-chromium (U-Cr) by an electrothermic atomization-atomic absorption spectrometry (ETA-AAS) method. In this study, we found that Cr exposure induced a decrease both in GSH (P < 0.0005) and GSH/oxidized glutathione (GSSG) ratio (P < 0.0001) in red blood cells from workers with respect to control subjects. Furthermore, we also demonstrated a significant decrease of plasma acid ascorbic levels (45.7 +/- 14.9 vs. 53.5 +/- 16.5 micromol/L; P < 0.05) and in total plasma antioxidant capacity (1,126.3 +/- 212.2 vs. 1,266.9 +/- 207.8 micromol/L; P < 0.05) in subjects exposed to Cr. No difference was found with regard to TBA-RM and thiol levels. This study demonstrated that in humans, an oxidative stress occurs for Cr exposures as low as those considered safe. This oxidative stress appears to be able to affect intracellular and plasmatic antioxidant defense.

Comparing several atomic spectrometric methods to the super stars: special emphasis on laser induced breakdown spectrometry, LIBS, a future super star

The “super stars” of analytical atomic spectrometry are electrothermal atomization-atomic absorption spectrometry (ETA-AAS), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). Many other atomic spectrometric methods have been used to determine levels of elements present in solid, liquid and gaseous samples, but in most cases these other methods are inferior to the big three super star methods. The other atomic methods include glow discharge emission, absorption and mass spectrometric methods, laser excited fluorescence emission and ionization methods, and flame and microwave plasma emission and mass spectrometric methods. These “lesser” methods will be compared to the “super star” methods based on a number of figures of merit, including detection power, selectivity, multi-element capability, cost, applications, and “age” of the methods. The “age” of the method will be determined by a modification of the well-known Laitinen “Seven Ages of an Analytical Method” (H.A. Laitinen, Anal. Chem., 1973, 45, 2305). Calculations will show that certain methods are capable of single atom detection, including several atomic absorption methods, as well as laser atomic ionization and fluorescence methods. The comparison of methods will indicate why the “super stars” of atomic spectrometric methods will continue to retain their status and what must be done for the lesser atomic methods to approach “super star” status. Certainly most of the lesser atomic spectrometric methods will have a limited place in the analytical arena. Because of the wide current interest and research activity, special emphasis will be placed on the technique of laser induced breakdown spectrometry (LIBS). Its current status and future developments will therefore be reviewed.

Estimation of chromium bioavailability from the diet by an in vitro method

An in vitro method was used to study the dialysable fraction of chromium (Cr) from the diet which simulates human gastric and intestinal digestion. The percentage of dialysed Cr was used to assess the bioavailability. The duplicate diet approach was used to obtain ten different sets of samples each representative of the normal diet consumed in southern Spain. In each case triplicate analysis of Cr was carried out by electrothermal atomization-atomic absorption spectrometry in acid-mineralized samples. The Cr dietary intake ranged from 16 to 117 μg/day, and the dialysable Cr fraction ranged from 0.4% to 1.6%. The Cr absorption was higher for low levels of daily dietary mu intake of Cr (lt; 40 μg) than for levels of 40–80 μg; for mu high levels (> 80 μg) there was an increase in the dialysable fraction. The energy and nutrient intake of these diets was also evaluated.

Determination of butyltin compounds by high-performance liquid chromatography-hydride generation-electrothermal atomization atomic absorption spectrometry

An ultrasensitive method for the determination of butyltin compounds has been developed coupling liquid chromatography with electrothermal atomization atomic absorption spectrometry by means of a hydride generation-in situ trapping system. The eluent coming out from the HPLC column was mixed in a tee piece assembly with hydrochloric acid and sodium tetrahydroborate; the reacting solution was carried through the mixing coil to the gas–liquid separator and the generated hydrides were stripped from the solution, introduced into the graphite atomizer through the quartz tube and collected on a Pd-treated platform. The quartz tube was then removed from the injection hole of the graphite tube and the atomic absorbance measured. For each considered tin species (inorganic tin, monobutyltin, dibutyltin, tributyltin) hydride generation conditions were studied in a multivariate way by a suitable experimental design. The resulting analytical performance of the HG-in situ trapping-ETAAS set-up was adequate for the determination of organotin species in environmental samples and therefore it was used as a metal-specific detector for HPLC analysis of this class of compounds. Detection limits of 0.84, 1.66 and 20.4 ng were obtained for mono-, di- and tributyltin, respectively. The system has been used for the determination of butyltin species in certified reference materials of marine samples such as mussel tissues and sediments.

Aluminum Content in Foods and Beverages Consumed in the Spanish Diet

A reliable and rapid method for determining aluminum content in foods and beverages was developed using electrothermal atomization-atomic absorption spectrometry (ETA-AAS) using previous optimization of the time-temperature program for the graphite furnace. The samples were subjected to acid mineralization with HNO 3 and V 2 O 5 . The technique used slurries for assay in samples of dairy products. The detection limit was 4.0 pg. The mean recovery obtained ranged from 98.5% to 99.0%. The variation coefficient ranged from 3.2% to 5.2%. The results obtained ranged from 1.362 to 6.610 μg/g in seafood, 0.171 to 29.688 μg/g in vegetables, 19.560 to 70.100 μg/g in olive oil, 0.424 to 6.430 μg/g in dairy products and 25.600 to 58.057 μg/g in stimulant drinks and infusions. This study contributes new data on the Al content of a variety of foods and beverages in Spain and such data are important for composition tables. The higher presence corresponded to seafood, vegetables and dairy products. Their contribution to Al dietary intake were estimated.

Antimony in drinking water, red blood cells, and serum: development of analytical methodology using transversely heated graphite furnace atomization-atomic absorption spectrometry.

An atomic absorption spectrometric (AAS) method has been developed for determining microg/L levels of Sb in samples of water and blood. The AAS method is based on the concept of stabilized temperature platform furnace atomization (STPF) realized through the use of a transversely heated graphite atomizer (THGA) furnace, longitudinal Zeeman-effect background correction, and matrix modification with palladium nitrate-magnesium nitrate-nitric acid. The method of standard additions is not mandatory. The detection limit (3 standard deviations of the blank) is 2.6 microg Sb/L for the water, red blood cells (RBCs), and serum samples. Data are presented on the degree of accuracy and precision. The THGA-AAS method is simple, fast, and contamination-free because the entire operation from sampling to AAS measurement is carried out in the same tube. The method has been applied to the determination of Sb in some leachate tap water samples derived from a static copper plumbing system containing Sn/Sb solders, and in small samples (0.5 ml) of RBCs and serum derived from rats given Sb-supplemented drinking water.

Reference values of urinary chromium in Italy.

The paper describes the results of a polycentric study for the assessment of reference values of urinary chromium (U-Cr) in the Italian population. A total of 890 subjects (58.3% males and 41.7% females) were selected on the basis of standardized criteria in eight different areas of Italy. Urinary chromium was determined on morning spot samples collected using standardized procedures. The U-Cr was determined independently by three laboratories using an Electrothermic atomization-Atomic Absorption Spectrometry (ETA-AAS) method with a detection limit of 0.05 microgram/l, adopting-for the statistical analysis-the median value of the results of the three laboratories. The between-laboratories within-subjects standard deviation was 0.049 microgram/l. Due to the high proportion (approx, 28%) of undetectable chromium levels, the geometric mean (GM) and geometric standard deviation (GSD) were estimated using a procedure of linear interpolation. The analysis of the effects of some variables (sex, age, center, residence, smoking and drinking habits) on the U-Cr values, was also performed, by multiple regression analysis after logarithmic transformation, using GM and SD. The reference value of U-Cr was of 0.08 microgram/l as an estimated GM, whereas the expected distribution ranged from not detectable (nd) (95% CI = nd-0.06) to 0.24 microgram/l (95th percentile; 95% CI = 0.20-0.31). Among the variables studied, only geographical area and sex significantly influenced the U-Cr levels. In subjects selected in the provinces of Bari and Venice values of U-Cr were significantly lower than those determined in subjects residing in other areas. From our investigation the reference values for U-Cr were lower than those obtained in previous investigations. In addition it confirms a further reduction in U-Cr levels following the previous decline reported in the 1970s and 1980s. In over 20 years U-Cr values in the general population dropped from values greater than 1 microgram/l to values between 0.5 and 0.2 microgram/l. The reasons of this progressive decline cannot be attributed in our opinion to a reduced intake of the metal, but mainly to the improvement in analytical instrumentation and methods. A further decrease may be ascribed to a more accurate definition of the reference groups and to a better control of pre-analytical factors. Considering that the reference values for U-Cr are much lower than those determined some decades ago, toxicological studies in order to verify the significance of biological limit values currently suggested for chromium seem to be necessary.

Cadmium levels in wine, beer and other alcoholic beverages: possible sources of contamination

An accurate and precise method is described for the direct determination of Cd in wine, beer and other alcoholic beverages by electrothermal atomization-atomic absorption spectrometry (ETA-AAS). The graphite furnace program was optimized and samples were pretreated with nitric acid and pentoxide vanadium in a digestion block at 120°C for 90 min. The results obtained were validated against microwave acid sample digestion. The analytical detection limit was 0.5 pg. The proposed method was applied to determine Cd in 134 samples of 10 different alcoholic beverages. The mean values ranged from 0.10 to 15.38 μg/l in wine, from not detectable to 0.80 μg/l in beer, and from not detectable to 11.52 μg/l in other alcoholic beverages such as cider, brandy, rum, whisky, gin, anisette, liquor and spirits. The wide variability of the results obtained emphasizes the multiplicity of factors than can influence the presence of Cd in these products. Because alcoholic beverages are widely consumed, they contribute a large fraction of cadmium intake, and therefore, strict control of this element is advisable.

Trace Metal Assay of Uranium Silicide Fuel

A comprehensive trace metal assay of uranium silicide, a fuel for nuclear research reactors that employs low-enrichment uranium, is carried out by atomic spectrometry. Of the list of specification elements, 21 metallic elements are determined by a direct current (dc) arc carrier distillation technique; the rare earths yttrium and zirconium are chemically separated from the major matrix followed by a dc arc/inductively coupled argon plasma (ICP) excitation technique in atomic emission spectrometry (AES); silver is determined by electrothermal atomization-atomic absorption spectrometry (ETA-AAS) without prior chemical separation of the major matrix. Gamma radioactive tracers are used to check the recovery of rare earths during the chemical separation procedure. The detection limits for trace metallics vary in the 0.1- to 40-ppm range. The precision of the determinations as evaluated from the analysis of the synthetic sample with intermediate range analyte concentration is better than 25% relative standard deviation (RSD) for most of the elements employing dc arc-AES, while that for silver determination by ETS-AAS is 10% RSD. The precision of the determinations for four crucially important rare earths by ICP-AES is better than 3% RSD.

Determination of Nickel in Biological Samples by Electrothermal Atomization-Atomic Absorption Spectrometry Involving a Prior Extraction with 1,5-Bis (Di-2-Pyridylmethylene) Thiocarbono-Hydrazide

Abstract The use of 1,5-bis(di-2-pyridylmethylene) thiocarbono-hydrazide as a reagent for the extraction of Ni(II), Co(II), Zn(II), Fe(II), Cd(II) and Cu(II) into methyl isobutyl ketone has been studied, and a method for the determination of nickel at ultra-trace (ng/ml) level has been developed, by using electrothermal-atomization (graphite furnace) atomic absorption spectrometry involving a prior extraction with the cited extracting reagent. The chief advantage of the proposed method lies in its maximum allowed aqueous-to-organic phase volume ratio of 15. It has been successfully applied to the determination of nickel substrates in various biological samples.

Flow-injection thermospray sample deposition for electrothermal atomization-atomic absorption spectrometry

A flow-injection system has been used successfully for thermospray sample deposition in electrothermal atomization-atomic absorption spectrometry (ETA-AAS). Under optimized conditions, i.e. for a sample flow-rate of 0.7 ml min , a thermospray vaporizer temperature of 300°C and a deposition temperature of the graphite furnace of 120°C, the sensitivity is equal to conventional ETA-AAS. At deposition temperatures higher than 120°C the sensitivity is slightly reduced, whereas above 170°C the sensitivity decreases rapidly. Tubes of graphite, pyrolytically coated graphite, totally pyrolytic graphite and glassy carbon behave similarly with respect to the temperature dependence of the thermospray sample deposition efficiency. Under the conditions stated a 10μl sample can be transferred in a few seconds, but much larger volumes (up to 500 μl in 2 mins) can also be introduced with a corresponding gain in sensitivity. The flow-injection thermospray deposition system can thus be used to cover a wide concentration range in ETA-AAS. With the thermospray vaporizer, sodium chloride concentrations up to 2% have been introduced into the furnace without clogging the fused silica capillary. Preliminary results indicate that thermospray deposition on a L'vov platform is feasible.

Glow Discharge Sputter Atomization for Atomic Absorption Analysis of Nonconducting Powder Samples

A methodology has been developed for the analysis of nonconducting (oxide) powder samples by glow discharge atomization-atomic absorption spectrometry (GDA-AAS). The mixing of an oxide powder with a copper host matrix (1:9) allows pressing of a disk sample for glow discharge sputtering. Sample-to-sample precisions are on the order of 3–4% for iron in a geological specimen. The ability to generate analytical working curves is demonstrated for the analysis of iron by mixing Fe (III) and Al (III) oxides in the copper matrix material. The possible utility of the methodology is illustrated by the analysis of iron in an NBS geological reference material. The ability to perform analyses of these sample types suggests its applicability to such matrices as ceramics, glasses, and refractory-based catalysts.

Computer aided signal analysis in electrothermal atomization-atomic absorption spectrometry—accuracy and precision: peak height vs peak area

A systematic approach to the question of the height or area calculation in electrothermal atomization-atomic absorption spectrometry (ETA-AAS) is given. Points studied are the real time sampling, power spectrum, temperature and the chemical composition of the sample. It turned out that generally the height gives somewhat more precise results for the furnace studied, the Varian CRA 90, but the difference with the area measurements was not dramatic. A far better approach is the measurement of the height multiplied by the peak time. Precision here can be as good as 1–2 % RSD on a concentration level of 0.3 μg 1 , while a characteristic mass of 0.041 μg is obtained. This shows how good ETA-AAS can be. However, with chemical more complex elements as lead, the mentioned precision will only be reached after sample destruction or matrix modification.

Furnace design in electrothermal atomization-atomic absorption spectrometry

The heating characteristics and analytical performance of conventional, longitudinally heated tubes and transverse heated ETA-AAS tubes are discussed, including the influence of the tube material on the different furnace designs. From the present study it can be concluded that the best furnace material is pyrolytically coated electrographite. Analytical results obtained with the presently available totally pyrolytic graphite tubes are at best similar to pyrolytically coated tubes, whereas glassy carbon tubes cannot successfully be used at temperatures higher than 2500°C. Transverse heated tubes of totally pyrolytic graphite and transverse heated integrated contact tubes are promising because of their spatially more homogeneous temperature distribution.

Kidney and liver levels of some major, minor and trace elements in two Ontario communities

The contents of Ag, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Se, Sr, Th, Ti and Zn in 143 autopsied liver and kidney specimens from two Ontario communities (Kingston and Ottawa) were determined using the techniques of inductively-coupled plasma-atomic emission spectrometry, and electrothermal atomization-atomic absorption spectrometry coupled with hydride evolution (As, Se), reduction-aeration (Hg), or solvent extraction (Pb). The majority of samples came from individuals older than 50 y. In general, the data for the various elements were independent of age or sex but showed some dependence on location for elements such as Cu, Fe, K, Mg, Mn, Na, P, Se and Zn. Despite these differences the elemental values of the liver and kidney samples from both the communities were within the normal range.

A pyrometric feedback system covering the entire temperature program for electrothermal atomization-atomic absorption spectrometry

A new pyrometric temperature feedback control system 1 1 Patent pending. for ETA-AAS is introduced which controls the entire temperature range needed for analysis. The system consists of a single infrared sensitive detector and independent feedback control circuitry for the three separate heating stages of a Varian CRA 63 or CRA 90 power supply to which it was added. The temperature region covered by the system encompassed from 300 to 3300 K. The precision of the temperature control amounts to ±20 K at 330 K., ±5 K at 700 K and ±2 K at 2300 K. In order to test the performance of the system, lead in blood and cadmium in urine were determined. Substantial improvements as compared to the conventional system were obtained with respect to optimization of the temperature program, precision and sensitivity.