Short-team stability of trace metals in estuarine water samples

The short-term (up to 24 h) stability of estuarine water with high (22%?) and low (<21%?) salinity, stored unacidified in polythene containers prior to filtration, preservation and determination of dissolved trace metals, was assessed. For the-salinity sample a massive (140%) increase in copper concentration was observed, indicating desorption from the particulate phase; a similar, although less pronounced (11%) effect was found for the high-salinity sample, Evidence was also obtained for a significant loss (30%) of lead from a pre-filtered low-salinity sample, suggesting appreciable adsorption to the container walls. For cadmium and nickel, no substantial changes in concentration were observed.     

Analytical quality control: Sampling procedures to detect trace metals in environmental matrices

The problem of contamination during the collection of samples of environmental interest to detect trace metal is discussed. Attention is focused on the leaching of metals from sampling devices used to collect surface and deep seawater. A procedure to test metal release is applied to emphasize the importance of conditioning samplers before use. The procedure for checking the contamination extent and decontamination of firn and ice cores to detect ultratrace elements (particularly Cd and Pb) is presented and applied to some firn cores collected in Antarctica during the 1990–1991 Italian expedition.     

Analytical quality control program used by the trace elements in foods and diets sub-network of the FAO European cooperative network on trace elements

Summary The analytical quality control program employed by the ongoing FAO study on 14 trace elements in nationally representative staple foods of European countries is presented. The analytical quality control used is based on: 1) precautions taken to avoid trace element contaminations or losses during sampling and sample handling; and, 2) on methods used to guarantee that the actual determinations yield correct results. The precautions are presented. A number of certified biological reference materials (RMs) were used to validate the analytical methods employed. The following staple food RMs were also prepared: wheat flour, potato powder, animal muscle (pork) and milk powder. They were tested for homogeneity and subjected to an interlaboratory comparison study on the basis of which recommended values for trace element concentrations were defined. Further, the mean relative standard deviation for the 95% confidence limits of the medians in all RMs was below 5% for Ca, Mg and Zn; below 10% for Mn; below 15% for Fe, Cu and Se; and below 25% for Mo and Ni. These RMs were used to control the analytical quality of the trace element determinations in the actual samples. It is concluded that important contaminations were avoided in sampling and sample handling and that use of the RMs described was necessary to guarantee the analytical quality of the results.     

The determination of trace metals in microlitre samples by plasma torch excitation

A method is described for multi-element analysis in which microlitre samples of solutions of inorganic and organic materials are used. Samples are introduced into the high-frequency plasma torch by means of a small heated nebulizer, and the emission is recorded by conventional spectrographic techniques. Detection limits for various metals are in the range l0⁻⁹–10⁻¹⁰ g; at the 10⁻⁹ level, precision is of the order of 5%. Examples of the application of the method to the determination of trace elements in oil, organic compounds and blood are given.     

Graphite furnace atomic absorption analysis of marine samples for trace metals

Trace element determinations by graphite furnace atomic absorption spectrometry which are pertinent to the analysis of marine samples are highlighted. Results for the direct introduction of solids, slurries and dissolved samples of fauna, sediments and saline waters are discussed. Examples drawn from recent literature show that typical samples which benefit most from direct solid sampling are those that do not require the very highest accuracy or precision. No clear consensus amongst users of this technique has emerged regarding the choice between peak height or area recording or the need to standardize by aqueous calibration, the method of additions or use of matrix matched solids. Slurry sampling overcomes several limitations associated with direct solid sampling and whereas generalizations serve little purpose in assessing the applicability of the direct solid sampling approach, slurry sampling holds great promise for widespread use. Examples of external and in situ concentration techniques necessary to augment the relative detection power of the system for the analysis of saline waters are also given. These include an examination of “classical” procedures utilizing chelation-solvent extraction, immobilized ligands and precipitation methods as well as techniques which rely on sequestration in the furnace of volatile analyte species generated in external cells.     

New sorbents and indicator powders for preconcentration and determination of trace metals in liquid samples

Two approaches to immobilize complex-forming analytical reagents (PAN, PAR, Xylenol orange, Brombenzothiazo, Crystal violet, Cadion, and Sulfochlorophenolazorhodanine) for the preparation of new sorbents and indicator powders are suggested: on-line coating of reversed-phase silica gel by reagents or doping of porous sol-gel silica with reagents. The retention of Ag, Cd, Cu(II), Co(II), Fe(III), Mn(II), Ni, Pb, and Zn on the sorbents developed was investigated. Quantitative sorption and desorption conditions were optimized. Procedures for the determination of Cd, Cu(II), Fe(III), Pb, and Zn with flame atomic absorption, spectrophotometric, and diffusion scattering spectrometric detection were elaborated. Detection limits for Cd, Cu(II), Fe(III), Pb, and Zn were 3 μg/L, 6 μg/L, 5 μg/L, 40 μg/L, and 1 μg/L, respectively. The procedures were used for the analysis of various real samples, e.g., natural and waste waters, and food.     

New sorbents and indicator powders for preconcentration and determination of trace metals in liquid samples

Two approaches to immobilize complex-forming analytical reagents (PAN, PAR, Xylenol orange, Brombenzothiazo, Crystal violet, Cadion, and Sulfochlorophenolazorhodanine) for the preparation of new sorbents and indicator powders are suggested: on-line coating of reversed-phase silica gel by reagents or doping of porous sol-gel silica with reagents. The retention of Ag, Cd, Cu(II), Co(II), Fe(III), Mn(II), Ni, Pb, and Zn on the sorbents developed was investigated. Quantitative sorption and desorption conditions were optimized. Procedures for the determination of Cd, Cu(II), Fe(III), Pb, and Zn with flame atomic absorption, spectrophotometric, and diffusion scattering spectrometric detection were elaborated. Detection limits for Cd, Cu(II), Fe(III), Pb, and Zn were 3 μg/L, 6 μg/L, 5 μg/L, 40 μg/L, and 1 μg/L, respectively. The procedures were used for the analysis of various real samples, e.g., natural and waste waters, and food. Received: 17 July 1997 / Revised: 20 January 1998 / Accepted: 5 February 1998     

The determination of trace metals and fluoride in mineralogical and biological samples from the marine environment

Résumé Par l'analyse par activation, on recherche des traces de métaux et de fluor dans la poussière atmosphérique récoltée au-dessus des différents océans. On a utilisé l'activation neutronique pour l'analyse des métaux, l'activation aux photons pour évaluer la teneur en fluor. On discute de fa?on détaillée l'importance des résultats obtenus pour Hg et F en fonction du milieu. L'étude du rendement d'extraction du mercure a été faite au laboratoire au moyen d'algues marines, phaeodactylum tricornutum. Au cours d'expériences préliminaires faites en utilisant le radiotraceur (¹⁹⁷Hg), on a évalué différents paramètres expérimentaux. On compare les résultats finaux pour les concentrations de mercure dans les algues avec ceux obtenus par une méthode d'analyse par absorption atomique.      

Single-column method of chelation ion chromatography for the analysis of trace metals in complex samples

A single-column chelation ion chromatographic system for the preconcentration and separation of trace transition metals is described. The system includes standard chromatographic equipment with a post-column reagent system based on the reaction with 4-(2-pyridylazo)resorcinol followed by photometric detection at 495 nm. Iminodiacetic acid bonded to 5 μm silica (Diasorb IDA) was used as a chelating stationary phase. The strong complexing ability in combination with good kinetics of complexation and ion-exchange selectivity of iminodiacetic functional groups allow both preconcentration of Mn, Co, Cd, Zn, Ni and Cu from waters of high salinity and efficient separation with the same column. The retention characteristics of alkaline-earth and transition metal ions on Diasorb IDA silica (250×4 mm I.D.) column was investigated for a variety of eluents including nitric acid, maleic, malonic, citric, dipicolinic, picolinic, tartaric and oxalic acids. The influence of ionic strength on retention of metal ions involving high nitrate and chloride concentrations was also evaluated. The baseline separation of preconcentrated metals was achieved using a three-step gradient elution scheme which involved first, flushing of the column loaded with the sample with 0.5 M KCl−0.5mMHNO₃ for 10 min, followed by 80 mM tartaric acid for 20 min and finally 10 mM picolinic acid for 20 min.     

Direct analysis of solid samples by GFAAS – determination of trace heavy metals in barytes

Solid sampling graphite furnace atomic absorption spectroscopy (SS-GFAAS) has been used for the determination of traces of heavy metals (Cd, Pb, Cu, Cr, Ni, V and As) in barytes over a wide concentration range, e.g. Cd from 0.023 to 27.0 μg/g and Pb from 1.54 to 3509 μg/g.The necessity of determining heavy metals in commercial barytes (naturally occurring barium sulfate), a mineral important to the oil industry because of its use in drilling muds, is discussed. The problems presented by the analysis of this difficult matrix are elegantly solved by using SS-GFAAS for the direct determination of heavy metals. A high-performance graphite furnace AAS with D₂-background correction system and a transversely heated graphite atomizer was used for the investigations. The spectrometer was combined with a mechanical sampling module and an ultramicrobalance. The transfer of solid samples (sample weights 0.031–0.686 mg) into the atomizer was carried out by using an optimized graphite platform as the sample carrier. Calibration curve techniques and standard addition methods were employed using external standards (CRMs). Problems associated with signal deformations like multiple peaks, tailing or shoulders are also discussed and possibilities to solve the problems are given. The influence of the homogeneity of solid samples on the precision and accuracy are shown in a real example. The results obtained by SS-GFAAS were compared with results by other methods like X-ray fluorescence spectroscopy (XRF) and flame AAS after aqua regia microwave extraction. This study has demonstrated that SS-GFAAS is a very powerful and easy-to-use method for quick and accurate analysis of barytes. Received: 9 November 1998 / Revised: 29 January 1999 / Accepted: 2 February 1999     

Geochemistry and health burden of radionuclides and trace metals in shale samples from the North-Western Niger Delta

Organic sedimentary rock samples were collected from three Oil Wells in the North-Western Niger Delta, Nigeria in order to determine their natural radioactivity and elemental geochemistry, with the aim of determining the concentrations of major radionuclides and their radiological and environmental health implication. The PIXE method of IBA technique and an accurately calibrated Si(Li) detector system was used to measure the elemental concentration of the sediment samples. The radionuclides identified belong to the decay series of naturally occurring radionuclides headed by ²³⁸U and ²³²Th along with the non-decay series radionuclide, ⁴⁰K. The activity concentrations of the radionuclides and their derived dose were then calculated. The average activity concentrations of ⁴⁰K were 248 Bq/kg for Well A, 261 Bq/kg for Well B and 273 Bq/kg for Well C. For ²³²Th the activity concentrations were 1,043 Bq/kg for Well A, 1,400 Bq/kg for Well B, 1,434 Bq/kg for Well C. ²³⁸U activity concentrations were 2,210, 3,508 and 250 Bq/kg for the Oil Wells A, B, C, respectively. The equivalent dose ranges from 8.5 ± 1.1 to 24.3 ± 2.1 mSv/year with a mean of 14.5 ± 2.2 mSv/year for Oil Well A, 2.4 ± 0.1–75.0 ± 1.2 mSv/year with a mean of 21.5 ± 1.1 mSv/year for Oil Well B and 3.7 ± 0.2–10.7 ± 0.6 mSv/year with a mean of 9.4 ± 2.5 for Oil Well C. The detected trace metals were majorly V, Ni, Pb, Fe, Cr, Cu, Zn, Co and their concentrations together with those of the radionuclides are compared with the relevant world standard limits. The results obtained were high, and hence, the radioactivity level and trace element content of the sediment samples from the North-Western Niger Delta Oil province could constitute health hazard to occupationally exposed workers, and to the public if not properly disposed. However, despite the careful disposal practice claims by the Oil industries, and given the high concentrations, the sediments could still pose an intrinsic health hazard considering their cumulative effects in the environment.     

Dithione as chelator in the flow injection separation and pre-concentration system of trace metals in biological samples

Dithione was used as chelator in the flow injection-knotted reactor separation and pre-concentration system coupled to flame atomic absorption spectrometry to determine trace amounts of Cu, Cd, Zn, Co in biological standard samples. Peak height was used for quantitative purpose. Alkali and alkaline earth elements, which could not chelate with dithione were separated from the objective metals; competition between trace metals were avoided for the strong chelating ability of dithione. Compared to diethyldithiocarbamate and pyrrolidine dithiocarbamate (APDC), dithione was used for multi-element detection with lower chelator concentration and better analytical performance. Concentration factors of 23.4-69.3 were obtained using dithione, with the detection limits of 1.06-2.56 μg/l. The system developed was used to determine trace metals in certified biological reference materials of human hair, pig liver and sea prawn after routine digestion, the results obtained agreed well with the certified values, relative standard deviations of the determinations were at the range of 2.10-3.02%.     

A low-cost flame atomic absorption spectrometry method for determination of trace metals in aqueous samples

A simple and fast method for the extraction into xylene of sub mug l(-1) concentrations of metals using ammonium diethyldithiophosphate (DDTP) as a complexing reagent and their subsequent determination by flame atomic absorption spectrometry is described. The method was tested in sea water spiked with Au at a concentration of 3.0 mug l(-1). The extraction was carried out until the aqueous to organic phase ratio achieved a 1000-fold preconcentration of metal. Optimisation of extraction parameters and the effect of Fe interference was investigated. Sea water samples spiked with Au produced an average recovery of 95% and the detection limit (3sigma) in deionized water was 2.9 ng l(-1). High enrichment factors could be obtained due to the small final volume (mul) of organic solvent.     

Speciation of trace metals in environmental samples at the fisheries laboratory,Burnham on crouch

The methods used by the MAFF Directorate of Fisheries Research for analysis of organometallic compounds are described. These analytical techniques are used for determination of trace quantities of the compounds in water, sediment and biota in UK estuaries and coastal waters.     

Determination of some trace metals with a new synthesized polymer resin by FAAS in various tea and herbal plants samples

In this work, a new polymer resin with a functional groups capable of holding trace metals has been synthesized. The structure of polymer resin has been examined by BET-N₂ method analyzer, IR spectrometer, scanning electron microscope (SEM) and elemental microanalyser. The synthesized polymer resin was used for the simultaneous separation and preconcentration of the trace metals from various tea and herbal plants samples. After extraction process, flame atomic absorption spectrometry (FAAS) was used to determine the trace metals. The analytical parameters and solid phase extraction (SPE) performance such as pH, sample volume, flow rates of sample, flow rates of eluent, concentration, volume and type of eluent and effect of interference ions, were investigated. The limits of detection (DL) of the SPE procedure for trace metals, were calculated to be (3s) in the range of 0.9?4.0 μg L^?1 (n = 21) and the factors of preconcentration (PF) were obtained at 200 for Cd, Co, Cu, Fe, Ni and Zn, and at 50 for Cr, Mn and Pb ions and the relative standard deviation (RSD) at ≤ 2% (n = 11).     

Determination of some toxic trace metals in Nigerian river and harbor water samples by neutron activation analysis

The determination of As, Cd, Cr, Hg, Mn, Mo, Ni, Sb, and Se in two Nigerian rivers and two Nigerian harbor waters is described. The water samples were preconcentrated by both evaporation at room temperature and freeze evaporation under reduced pressure. Postirradiation chemical separation of sodium, using hydrated antimony pentoxide (HAP) in 6M HCl, and of bromine, by oxidation with KMnO₄ and subsequent removal by extraction with CHCl₃, was employed. The measured concentrations of these elements in some water samples, which are relatively high, can be attributed to local pollution.     

Determination of alkali metals in control and AD brain samples by different techniques

Several metals are suspected or known to be involved in neurological disorders such as Alzheimer's disease (AD), therefore, elemental distribution studies have received intense attention for years. The present work focuses on a group of lesser studied elements in this context, alkali metals.Previously, an adequate neutron activation analysis (NAA) method has been developed and applied successfully for the determination of Na, K, Rb and Cs in brain samples of control subjects. This work has been extended to include AD patients, so that average values, distribution patterns and interpersonal variability could be compared and possible correlation between control and AD data could be studied.Despite the merits of the technique, its drawbacks are evident. Therefore, applicability of rapid spectrochemical methods as alternatives has been investigated. ICP-AES has been used for analysis of Li, Na and K. No interferences were observed, but ultrasonic nebulisation was needed for Li quantification. Rb and Cs were measured by ICP-MS with In as internal standard. Agreement between different techniques is found to be good for Na, K and Rb, while Cs values show somewhat higher differences.     

Parameter selection for peak alignment in chromatographic sample profiling: objective quality indicators and use of control samples

In chromatographic profiling applications, peak alignment is often essential as most chromatographic systems exhibit small peak shifts over time. When using currently available alignment algorithms, there are several parameters that determine the outcome of the alignment process. Selecting the optimum set of parameters, however, is not straightforward, and the quality of an alignment result is at least partly determined by subjective decisions. Here, we demonstrate a new strategy to objectively determine the quality of an alignment result. This strategy makes use of a set of control samples that are analysed both spiked and non-spiked. With this set, not only the system and the method can be checked but also the quality of the peak alignment can be evaluated. The developed strategy was tested on a representative metabolomics data set using three software packages, namely Markerlynx™, MZmine and MetAlign. The results indicate that the method was able to assess and define the quality of an alignment process without any subjective interference of the analyst, making the method a valuable contribution to the data handling process of chromatography-based metabolomics data.     

Modified pyrohydrolysis apparatus for the separation of fluorine and chlorine trace impurities from nuclear fuel samples for quality control analysis

A quartz pyrohydrolysis apparatus designed for the safe handling of pyrophoric carbide nuclear fuel samples while separating C1 and F trace impurities for quality control analysis is described. It has several advantages over the commonly used pyrohydrolysis apparatus. Performance of the apparatus during routine analysis of a large number of nuclear fuel samples has been found to be quite satisfactory.