Trace metal analyses in honey samples from selected countries. A potential use in bio-monitoring

Honey is a sweet product made by bees using nectar from flowers. Concentrations of Ca, K, Mg, Fe, Zn, Mn, Cu, Pb and Cd were determined in 13 honey samples from the selected regions around the world. Levels of Ca, Mg, Cu, Fe, Zn and Mn were measured using flame atomic absorption spectrometry (FAAS). Potassium concentration was determined via flame photometry. Concentrations of Cd and Pb were determined using the electrothermal technique (ETAAS). It was estimated that the examined samples of honey from Greece, Turkey, Spain, Poland, Mexico, Argentina and Italy were of good quality in terms of metal concentrations (compliant with the norms referring to food products – WHO, Fifty-third Report of the joint FAO/WHO Expert Committee on Food Additives; Technical Report Series 776, Geneva), although the analysed samples were not free of heavy metals. The concentrations of the elements in the honey samples ranged from 2.38 to 9.31 μg · g^?1 for Zn, from 3.86 to 35.10 μg · g^?1 for Fe, from 0.19 to 21.64 μg · g^?1 for Mn, from 49.53 to 1006.90 μg · g^?1 for Ca, from 388.25 to 4761.50 μg · g^?1 for K and from 0.20 to 1.53 μg · g^?1 for Cu and regarding heavy metals from 0.11 to 2.78 μg · g^?1 for Pb and from 0.02 to 0.44 μg · g^?1 for Cd. According to these results it was found that the concentrations of heavy metals in the honey samples (except for alfalfa honey and eucalyptus honey from Italy) were under the acceptable limits for foods set out by the FAO/WHO. It was confirmed that the application of chemometric tools supports the extraction of significant information from analytical data, even though the availability of samples is not fully sufficient (this problem is often encountered in environmental analyses).     

Molybdenum(VI) Oxide-Modified Silica Gel as a Novel Sorbent for the Simultaneous Solid-Phase Extraction of Eight Metals with Determination by Flame Atomic Absorption Spectrometry

A silica-based inorganic sorbent was synthesized by the thermal decomposition of ammonium heptamolybdate on silica and applied for the preconcentration and simultaneous determination of Cd, Co, Cr, Cu, Fe, Mn, Ni, and Pb in river water samples using a column system with flame atomic absorption spectrometry. Attenuated total reflection-Fourier transformation infrared spectroscopy, scanning electron microscopy, and electron dispersive spectroscopy were used for sorbent characterization. The effects of pH, sample volume, eluent type, eluent concentration, eluent volume, sample flow rate, and matrix ions (Al, Bi, Ca, Mg, and Zn) on the recovery of the metals in model solutions were investigated. The adsorption capacities (µmol g^?1) of SiO₂-MoO₃ were 88.96 (Cd), 169.69 (Co), 153.85 (Cr), 188.88 (Cu), 179.05 (Fe), 163.81 (Mn), 136.31 (Ni), and 38.61 (Pb). The detection limits of the method were 9.09, 10.82, 10.77, 49.57, 31.64, 6.40, 8.86, 19.15?µg L^?1 for Cd, Co, Cr, Cu, Fe, Mn, Ni, and Pb, respectively, with a preconcentration factor of 25. The developed method was used for the determination of the target metals in real samples and the recoveries for spiked samples were found to be from 91.2% to 102.9%.     

Direct multielement determination of trace elements in boron carbide powders by direct current arc atomic emission spectrometry using a CCD spectrometer

The use of direct current arc atomic emission spectrometry (DC-arc-AES) with a CCD spectrometer for the direct determination of the trace impurities Al, Ca, Cr, Cu, Fe, Mg, Mn, Na, Ni, Si, Ti, and Zr in three well characterized boron carbide powders is described. The detection limits obtained by the procedure were found to be between 0.2 (Mg) and 25 (Na) ??g?g^?1 for the above elements. Three boron carbide powder samples with trace element concentrations between 0.9 (Cu) and 934 (Si) ??g?g^?1 for Al, Ca, Cr, Cu, Fe, Mg, Mn, Na, Ni, Si, Ti, and Zr ?? including the standard reference material ERM?-ED102 ?? were analyzed by DC-arc-AES. The relative standard deviations for 9 measurements when using 5.0?±?0.3?mg of the respective samples were found to vary from 6.2 to 27% for Al and Cu, respectively. The trace elements Al, Ca, Cr, Cu, Fe, Mn, Ni, Si, Ti and Zr could be determined in the standard reference material and their concentrations determined by DC-arc AES were found to be between 89 and 116% of the accepted values. Fe and Ti were determined by DC-arc AES in the three boron carbide samples as well as in Al₂O₃, BN, SiC, coal fly ash, graphite and obsidian rock. The correlation coefficients of the plots of the net intensities versus the accepted values over the concentration ranges from 18 to 1750 and from 6 to 8000???g?g^?1 are 0.999 and 0.990 for Fe and Ti, respectively.

Assessment of metal contamination in an urban drainage system (using water and tilapia, Oreochromis spp.) in view of human health effect. A case study of some selected communities in Cape Coast township in Ghana

This research work aimed at studying the metal content of water and tilapia fish sample, Oreochromis spp., from a wastewater-fed pond around the University of Cape Coast community using instrumental neutron activation analysis. The metals studied were Al, As, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, V and Zn. In the water samples the order of elemental concentrations at sampling point 1, in ??g/g, was K (75.96?±?0.92), Na (18.52?±?0.35), Al (6.00?±?0.89), Mn (3.28?±?0.44), As (3.08?±?0.40), Mg (1.56?±?0.17), Ca (0.70?±?0.08), Cu (0.54?±?0.08) and V (0.04?±?0.01). Co, Cr, Fe and Zn were below detection limits of INAA. The order of elemental concentrations in the water at point 2 was as follows: Na (4.99?±?0.14), K (4.82?±?0.89), Mn (4.40?±?0.53), Mg (2.92?±?0.37), Al (1.98?±?0.21), As (0.69?±?0.10), Ca (0.24?±?0.07) and V (0.23?±?0.06) with Co, Cr, Cu, Fe and Zn falling below the detection limit of INAA. The concentrations recorded for Al, As, Cu and Mn in the water samples were all above WHO permissible limits. The mean levels of heavy metals in the soft tissue of tilapia was of the order: K?>?Mg?>?Fe?>?Ca?>?Na?>?Al?>?Mn?>?Zn?>?V?>?Cu?>?Cr?>?Co. Arsenic was below detection limit. The transfer factor values calculated for the metals Al, Ca, K, Mg, Mn, Na and V were all greater than one indicating movement of metals from the water column to the tilapia species. The hazard index (HI) calculated for Al, Fe, Mn and V suggested possible occurrence of adverse health effects (HI?>?1) where as the HI value obtained for Cr, Cu and Zn (i.e., HI?<?1) suggested unlikely adverse effects occurring.     

Determination of zinc in marine/lacustrine sediments by graphite furnace atomic absorption spectrometry using Pd/Mg chemical modifier and slurry sampling

Effectiveness of Pd/Mg chemical modifier for the accurate direct determination of zinc in marine/lacustrine sediments by graphite furnace atomic absorption spectrometry (GF-AAS) using slurry samples was evaluated. A calibration curve prepared by aqueous zinc standard solution with addition of Pd/Mg chemical modifier is used to determine the zinc concentration in the sediment. The accuracy of the proposed method was confirmed using Certified Reference Materials, NMIJ CRM 7303-a (lacustrine sediment) from National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Japan, and MESS-3 (marine sediment) and PACS-2 (marine sediment) from National Research Council, Canada. The analytical results obtained by employing Pd/Mg modifier are in good agreement with the certified values of all the reference sediment materials. Although for NRC MESS-3 an accurate determination of zinc is achieved even without the chemical modifier, the use of Pd/Mg chemical modifier is recommended as it leads to establishment of a reliable and accurate direct analytical method. One quantitative analysis takes less than 15 minutes after we obtain dried sediment samples, which is several tens of times faster than conventional analytical methods using acid digested sample solutions. The detection limits are 0.13?µg?g^?1 (213.9?nm) and 16?µg?g^?1 (307.6?nm), respectively, in sediment samples, when 40?mg of dried powdered samples are suspended in 20?mL of 0.1?mol?L^?1 nitric acid and a 10?µl portion of the slurry sample is measured. The precision of the proposed method is 8–15% (RSD).     

A new approach for determination of crustal and trace elements in airborne particulate matter

An ICP-OES procedure was developed for fast and accurate determination of various crustal (Al, Ca, Fe, Mg, Si) and trace elements (Ba, Cu, Mn, Na, K, Sr, Ti, Zn) in airborne particulate matter. The method is based on a preliminary treatment of the aerosol samples with a mixture of nitric acid and hydrogen peroxide at elevated temperature leading to a mineralization of the organic sampling substrate, dissolution of soluble material and homogeneous suspension of the remaining non-soluble fraction. After dilution the derived slurry solutions were measured using ICP-OES. The reproducibility of analysis given as the relative standard deviation (% RSD) varied between 3.2 and 6.8% for bulk constituents such as Al, Ca, Fe, Mg and Si whereas values ranging from 3.5 to 9.1% were obtained for trace metals present with distinctly lower abundance in PM10 (e.g. Ba, Cu, Mn, Sr, Zn). The limits of detection (LOD) calculated as three times the standard deviation (3σ) of the signal derived from filter blank samples ranged from approximately 1?ng?m^?3 (Sr) to 71?ng?m^?3(Ca). The developed procedure was evaluated by comparing the obtained results with the findings derived for the same set of aerosol samples analyzed using a microwave procedure for sample dissolution with subsequent ICP-OES analysis. Finally the developed procedure was applied for the analysis of crustal and trace elements in PM10 samples collected at an urban site (Getreidemarkt, Vienna) and a rural site (Hartberg, Styria), in Austria. The concentrations of the investigated crustal elements varied between some hundred ng?m^?3 and few µg?m^?3 with highest concentrations for Fe and Si, distinctly reduced concentrations ranging from some ng?m^?3 (Sr) to more than hundred ng?m^?3 (K) were found for trace elements. Observed PM10 concentrations were found to be in accordance to literature findings from urban sites in central Europe.     

Investigation of electrochemical hydride generation coupled to microwave plasma torch optical emission spectrometry for the determination of arsenic: analytical figures of merit,interference studies and applications to environmentally relevant samples

A continuous flow thin layer electrolysis cell with a Pt cathode in combination with a microwave plasma torch operated with Ar as working gas was used for the optical emission spectrometric determination of As with the hydride technique. Under the optimised conditions the limit of detection (3σ) in the case of the As(I) 228.81 nm emission line was 81 ng mL^?1. Especially the influence of the transition metals Cu(II), Fe(III) and Ni(II), of the hydride forming elements Sb(III), Se(IV) and Sn(II) and of Na on the determination of As was studied. Cu(II) was found to be the strongest interferent, as in the presence of 100 µg mL^?1 of Cu(II) the signal for 3 µg mL^?1 of As was reduced to 4% of the signal without interferent. Sn(II) and Sb(III) were found to yield an increase of the signal for As. L-cysteine and KI/ascorbic acid (1 : 1) at a concentration of 2% were found effective to reduce the interferences of Cu(II), Fe(III) and Ni(II). For a solution containing 3 µg mL^?1 of As and 100 µg mL^?1 of Ni(II) it was shown that in the presence of L-cysteine or KI/ascorbic acid the signal for As was 99% and 94% of the one without interferent, whereas it was only 43% without masking reagents. The procedure could be used for the determination of As in a digested coal fly ash standard reference material (NIST SRM 1633a®) with a certified value of 145 ± 15 µg g^?1 for As. A concentration of 131 ± 15 µg g^?1 was found. Additionally, As could be determined in two process water samples from a copper refinery. It was found that the amount of As determined with ECHG-MPT-OES agrees well with the values determined by FAAS and ICP-OES at the 0.02 and 1.6 g L^?1 level, respectively.     

Fast sequential multi-element determination of Ca,Mg, K,Cu, Fe,Mn and Zn for foliar diagnosis using high-resolution continuum source flame atomic absorption spectrometry: Feasibility of secondary lines,side pixel registration and least-squares background correction

The fast sequential multi-element determination of Ca, Mg, K, Cu, Fe, Mn and Zn in plant tissues by high-resolution continuum source flame atomic absorption spectrometry is proposed. For this, the main lines for Cu (324.754 nm), Fe (248.327 nm), Mn (279.482 nm) and Zn (213.857 nm) were selected, and the secondary lines for Ca (239.856 nm), Mg (202.582 nm) and K (404.414 nm) were evaluated. The side pixel registration approach was studied to reduce sensitivity and extend the linear working range for Mg by measuring at wings (202.576 nm; 202.577 nm; 202.578 nm; 202.580 nm; 202.585 nm; 202.586 nm; 202.587 nm; 202.588 nm) of the secondary line. The interference caused by NO bands on Zn at 213.857 nm was removed using the least-squares background correction. Using the main lines for Cu, Fe, Mn and Zn, secondary lines for Ca and K, and line wing at 202.588 nm for Mg, and 5 mL min^− 1 sample flow-rate, calibration curves in the 0.1–0.5 mg L^− 1 Cu, 0.5–4.0 mg L^− 1 Fe, 0.5–4.0 mg L^− 1 Mn, 0.2–1.0 mg L^− 1 Zn, 10.0–100.0 mg L^− 1 Ca, 5.0–40.0 mg L^− 1 Mg and 50.0–250.0 mg L^− 1 K ranges were consistently obtained. Accuracy and precision were evaluated after analysis of five plant standard reference materials. Results were in agreement at a 95% confidence level (paired t-test) with certified values. The proposed method was applied to digests of sugar-cane leaves and results were close to those obtained by line-source flame atomic absorption spectrometry. Recoveries of Ca, Mg, K, Cu, Fe, Mn and Zn in the 89–103%, 84–107%, 87–103%, 85–105%, 92–106%, 91–114%, 96–114% intervals, respectively, were obtained. The limits of detection were 0.6 mg L^− 1 Ca, 0.4 mg L^− 1 Mg, 0.4 mg L^− 1 K, 7.7 µg L^− 1 Cu, 7.7 µg L^− 1 Fe, 1.5 µg L^− 1 Mn and 5.9 µg L^− 1 Zn.     

Facilitating local analysis in northern regions: microwave plasma-atomic emission spectrometry for mercury determination in wild Atlantic salmon

An analytical procedure was developed to quantify mercury concentration in wild Atlantic salmon (Salmo salar) muscle tissue by cold-vapour microwave plasma-atomic emission spectrometry (CV-MP-AES) with microwave-assisted acid digestion. Muscle samples were collected from the Atlantic salmon Food, Social, and Ceremonial fisheries in Lake Melville, Labrador (Canada). Muscle samples were digested with nitric acid and hydrogen peroxide, mercury was stabilised with thiourea, reduced with NaBH₄, and quantified by CV-MP-AES. Analysis of fish protein certified reference material (CRM, DORM-3) by CV-MP-AES was used to assess the accuracy and precision of the procedure. CRM recovery averaged 88% with a relative standard deviation of less than 8%. The limits of detection were as low as 0.22 µg?L^?1 in solution which translate to 0.02 µg·g^?1. Mercury concentrations in salmon muscle tissue quantified by CV-MP-AES were not significantly different from results obtained by cold vapour-atomic fluorescence spectrometry (CV-AFS) from an accredited laboratory. Our results indicated that the CV-MP-AES procedure is appropriate for the quantification of mercury at background levels (range 0.15–0.29 µg?g^?1 dry weight) in wild fish of Labrador.     

Trace Determination of Manganese in Urine by Graphite Furnace Atomic Absorption Spectrometry and Inductively Coupled Plasma–Mass Spectrometry

This paper describes a simple and sensitive method for the determination of manganese in human urine by graphite furnace atomic absorption spectroscopy (GFAAS), which includes sample preparation by microwave digestion. Matrix modifier combinations, the digestion power, pyrolysis, and atomization temperatures were optimized. A mixture of 5.0 µg Pd(NO₃)₂ and 3.2 µg Mg(NO₃)₂ modifier presented the best performance. The optimal temperatures for pyrolysis and atomization were 1500°C and 1950°C, respectively. The GFAAS method was compared to inductively coupled plasma–mass spectrometry (ICP–MS) for the determination of manganese in urine. Analytical figures of merit for GFAAS and ICP–MS were: accuracy (3.46%, 2.19%), precision (3.61%, 5.84%), LOD (0.109 µg · L^?1, 0.015 µg · L^?1), LOQ (0.327 µg · L^?1, 0.045 µg · L^?1), and recovery (80–100%, 74–89%). Both methods were employed for the determination of Mn in urine and the results were compared statistically.     

Optimization of the Sample Preparation Procedure for the Determination of Trace Elements in Auricularia auricula by Inductively Coupled Plasma-Optical Emission Spectrometry

This study aimed to develop a precise and accurate method of sample preparation of Auricularia auricula for inductively coupled plasma-optical emission spectrometry-based trace element determination and to compare concentrations of seven trace elements (Mg, Fe, Mn, Zn, Ni, Cr, Sr) in six A. auricula samples belonging to three varieties with two cultivation substrates. Five sample preparation procedures, microwave-assisted digestion, nitric acid digestion with hot plate heating, nitric acid and perchloric acid digestion with hot plate heating, nitric acid digestion with ash content, and aqua regia digestion with ash content, were compared. The performance of the procedures was determined based on the precision and accuracy of the results and the limits of detection of the elements. The best results, with limits of detection of 0.60–6.60?ng?·?mL^?1 and recoveries for spiked samples between 93.80 and 105.00%, were found using nitric acid digestion with ash content. Six A. auricula samples were analyzed using the proposed procedure. Among the tested elements, the concentration of Fe was highest in all six A. auricula samples up to a maximum concentration of 284.83?µg?·?g^?1. The concentrations of Mn, Cu, and Ni increased in mixed stands (basswood, birch, and mongolica) compared with pine sawdust cultivation.     

Determination of traces of As,Cd, Cr,Hg, Mn,Ni, Sb,Se, Sn and Pb in human hair by triple quadrupole ICP-MS

With the wide range of metallic contaminants discharged in the environment, studying the human health requires a growing number of elements to be monitored in biological samples. Hair analysis has been suggested as a suitable tool for biomonitoring environmental and occupational exposure to toxic elements. This study describes a method for the determination of 10 trace elements in hair samples using ICP-QQQ-MS. Combining the power of the MS/MS high-energy Helium mode with the MS/MS O₂ mass-shift mode, the method offers great analytical performances with detection limits reaching 0.0014 µg g^?1 for As, 0.0016 µg g^?1 for Cd, 0.012 µg g^?1 for Cr, 0.0035 µg g^?1 for Hg, 0.0055 µg g^?1 for Mn, 0.10 µg g^?1 for Ni, 0.0012 µg g^?1 for Sb, 0.0083 µg g^?1 for Sn, 0.011 µg g^?1 for Se and Pb. The accuracy of the method was tested on a human hair ERM® certified reference material. Percent recoveries varied from 91.3% and 106.9% being always in the acceptance range of 90–110%. For all analysed elements, RSD% of repeatability ranged between 0.6% and 9.0% and those of intermediate precision did not exceed the limit of 20% being always lower than 10% (except for As). The proposed method was applied for the determination of trace elements in hair samples from 20 unexposed subjects. The geometric mean levels were as follows: Cr 0.28 µg g^?1, Mn 0.30 µg g^?1, Sn 1.04µg g^?1, Sb 0.07 µg g^?1, Hg 0.42 µg g^?1, As 0.02 µg g^?1, Cd 0.03 µg g^?1, Ni 0.51 µg g^?1, Se 0.45 µg g^?1 and Pb 1.83 µg g^?1. Element concentrations were in the same range with the reported data. The reported results may be useful for environmental exposure assessment or comparisons studies when establishing reference values of trace elements in exposed population.     

Calibration for Elemental Dental Tissue Analysis by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Teeth retain different elements at particular stages of life. Hence, the exposure over a selected time span may be characterized by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A Nd:YAG laser with emission at 266?nm was coupled to a quadrupole ICP-MS for the quantitative study of historical human teeth for Sr and Ba, elements of anthropological significance. A calibration approach incorporating the experimentally derived k coefficient is reported. The coefficients were established based on the mean concentrations of the analytes determined by pneumatic nebulization ICP-MS using acid-digested calcium phosphate standards and the intensities recorded during laser ablation of corresponding standards as pellets. The k values were 0.54?±?0.05 (µg?g^?1)^?1 and 4.49?±?1.09 (µg?g^?1)^?1 for Sr and Ba, respectively. This calibration approach provided local quantitative data and demonstrated statistically significant differences in Sr concentrations in enamel and dentine.     

Determination of Heavy Metal Content in Wild-Edible Mushroom from Jordan

The heavy metal content was investigated for six mushroom species native to Jordan. Metal (Cu, Pb, Cd, Fe, Zn, Mn, Ni, and Co) content in soil substrate and their relation to metal concentrations in mushroom and underlying soil were determined by flame and graphite furnace atomic absorption spectrometry. Mushroom species and soil were collected from different places in Jordan. The highest Cu level was 51.84 µg g^?1 for the species Lepista nuda; whereas, the lowest Cu level was found to be 18.51 µg g^?1 in Calvatia utriformis. Among the wild mushrooms, the highest Pb level was found as 4.81 µg g^?1 in Bovista plumbea, whereas the lowest Pb concentration was 2.01 µg g^?1 in Calvatia utriformis. The highest Cd level was determined as 1.9 µg g^?1 for Lepista nuda, whereas the lowest Cd level was 0.58 µg g^?1 for the species of Polyporus frondosus. The highest Zn level was 58.77 µg g^?1 for the species of Lepista nuda and the lowest Zn concentration was found 35.98 µg g^?1 in Calvatia utriformis. The highest Fe level was found as 317 µg g^?1 in Lepista nuda, whereas the lowest Fe concentration was 211.7 µg g^?1 in Calvatia utriformis. The highest Mn content was 36.55 µg g^?1 for Russula delica, whereas the lowest Mn level was 24.5 µg g^?1 for the species Bovista plumbea. The highest Ni content was found as 12.65 µg g^?1 for Russula delica, whereas the lowest Ni level was 0.17 µg g^?1 for Bovista plumbea. The highest Co content in the tested mushrooms was found as 3.5 µg g^?1 for the species of Agaricus bisporus, whereas the lowest Co level was 0.85 µg g^?1 for Polyporus frondosus. The results indicated that, in general, heavy metal contents in all mushroom species were lower than the underlying soil substrates except for some mushroom species.     

Ion Chromatographic Determination of Traces of Sodium,Magnesium and Chlorine in Gadolinium Nitrate

Abstract

Two independent and sensitive ion chromatographic methods with suppressed conductivity were developed for determination of traces of Cl, Na, and Mg in gadolinium-nitrate. Na-Mg was determined by cation-exchange column after matrix separation, whereas Cl was analyzed without matrix separation by high capacity anion-exchange column. Detection limit for Cl was 0.01 µg mL^?1 in sample solution and 1 µg g^?1 in solid sample. The reproducibility (100 µL injected) was better than 3%, 3% and 4% at 50, 25 and 50 µg L^?1 level for Cl, Na, and Mg respectively. The overall precision was better than ±7% for Na-Mg and ±5% for Cl.     

Elemental Analysis of Phytotherapeutic Products by Inductively Coupled Plasma–Tandem Mass Spectrometry

A procedure for the determination of As, Cd, Cr, Ni, Pb, and V in phytotherapy medicines by inductively coupled plasma–tandem mass spectrometry is reported. The use of tandem mass spectrometry with oxygen into an octopole reaction system at various gas flow rates and the combination of on-mass and mass-shift modes was evaluated. Cadmium, Cr, Ni, and Pb were determined as free atomic ions while As and V were determined as the oxides AsO⁺ and VO⁺ in the same run. Samples were prepared by microwave-assisted digestion with dilute nitric acid and hydrogen peroxide. Two plant-certified reference materials (apple leaves and tomato leaves) were used to check the accuracy. For tandem mass spectrometry with 0.5?mL min^?1 O₂, recoveries in the 85–113% were typically obtained and no statistical differences were observed at the 95% confidence level (t-test) in comparison with the certified values. Using these conditions, the limits of detection for the method were 0.01, 0.0002, 0.008, 0.008, 0.003, and 0.002?µg g^?1 for As, Cd, Cr, Ni, Pb, and V, respectively. The procedure was used for the analysis of four phytotherapic drugs and the determined concentrations were up to 0.168?µg g^?1 As, 0.03?µg g^?1 Cd, 0.82?µg g^?1 Cr, 1.18?µg g^?1 Ni, 0.52?µg g^?1 Pb, and 2.4?µg g^?1 V with average precision values of 8% as the relative standard deviation. The found concentrations were compared with limits proposed in official guidelines and, in most cases, the values were below the maximum limits allowed.     

Salen impregnated silica gel as a new sorbent for on-line preconcentration of cadmium(II)

A new sorbent – salen impregnated silica gel – was prepared and characterised for application as a minicolumn packing for flow-injection on-line preconcentration of cadmium(II). The system was coupled with flame atomic absorption spectrometer (FI-FAAS). The optimal pH for Cd(II) sorption was in the range of 7.4–8.8 and nitric acid (1%, v/v) was efficient as eluent. Sorption was most effective within the sample flow rate up to 7?mL?min^?1. Sorption capacity of the sorbent found in a batch procedure was 26.3?µmol?g^?1 (2.95?mg?g^?1). Enrichment factor (EF) and limit of detection (LOD) obtained for 120-second loading time were 113 and 0.26?µg?L^?1, respectively. The sorbent stability in the working conditions was proved for at least 100 preconcentration cycles. The evaluated method was applied to Cd(II) determination in various water samples.     

Cloud point extraction for the determination of cadmium and lead employing sequential multi-element flame atomic absorption spectrometry

A cloud point extraction procedure for pre-concentration and determination of cadmium and lead in drinking water using sequential multi-element flame atomic absorption spectrometry is described. 4-(2-thiazolylazo)-orcinol (TAO) has been used as complexing agent and the micellar phase was obtained using the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation. The conditions for reaction and extraction (surfactant concentration, reagent concentration, effect of incubation time, etc) were studied and the analytical characteristics of the method were determined. The method allows the determination of cadmium and lead with quantification limits of 0.30?µg?L^?1 and 2.6?µg?L^?1, respectively. A precision expressed as relative standard deviation (RSD, n?=?10) of 2.3% and 2.6% has been obtained for cadmium concentrations of 10?µg?L^?1 and 30?µg?L^?1, respectively, and RSD of 1.3% and 1.7% for lead concentrations of 10?µg?L^?1 and 30?µg?L^?1, respectively. The accuracy was confirmed by analysis of a natural water certified reference material. The method has been applied for the determination of cadmium and lead in drinking water samples collected in the cities of Ilhéus and Itabuna, Brazil. Recovery tests have also been performed for some samples, and results varied from 96 to 105% for cadmium and 97 to 106% for lead. The cadmium and lead concentrations found in these samples were always lower than the permissible maximum levels stipulated by World Health Organization and the Brazilian Government.     

Novel Chelating Resin for Solid-Phase Extraction of Metals in Certified Reference Materials and Waters

A new chelating resin, poly(diacetonitrile methacrylamide-co-divinylbenzene-co-vinylimidazole), was synthesized and characterized by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and elemental analysis. The novel resin was used for the first time as a chelating adsorbent for the preconcentration of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn from various samples by flame atomic absorption spectrometry. The adsorption capacities of the resin were 29.3, 31.6, 29.3, 27.3, 35.5, 31.7, 39.8, and 32.3?mg?g^?1 for Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn, respectively. The detection limits of the metal ions were from 0.42 to 3.21?µg?L^?1. A preconcentration factor of 30 for all metal ions was obtained. The precision of the method as the relative standard deviation was less than or equal to 2.6%. The described method was validated with certified reference materials and fortified real samples. The method was used for the determination of the analytes in well water and wastewater.     

ICP OES Simultaneous Determination of Ca,Cu, Fe,Mg, Mn,Na, and P in Biodiesel by Axial and Radial Inductively Coupled Plasma-Optical Emission Spectrometry

Abstract

A simple and rapid method for the simultaneous determination of seven trace elements in biodiesel by axial and radial view Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) is proposed, in which the sample is emulsified with Triton X-100 and water, and in which yttrium is employed as an internal standard. The better obtained quantification limits (10 s) were by axial view, 0.165, 0.099, 0.033, 0.007, 0.016, 0.132, 0.660 µg g^?1 for Ca, Cu, Fe, Mg, Mn, Na, and P, respectively, based on a sample mass of 1.0 g diluted to a final mass of 10 g in the analytical solution. Calibration was carried out with aqueous standards, thus avoiding the use of frequently instable organic standards. Elemental recoveries were in the range of 90 to 109% for all seven analytes studied, and also the precision of the method was satisfactory (RSD < 8%).