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This is the eighth Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2014. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. The review does not cover fractionation, which is sometimes termed operationally defined speciation. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. As in previous years, As and Se speciation continues to dominate the current literature and there has also been an increase in the number of publications concerning solid state speciation. This is presumably due to the increase in the number of synchrotron facilities available and a greater awareness of their potential for speciation studies.

The transport of arsenic from soil through to edible crop is important when assessing the potential health risks from a food source. Samples of soil, irrigation water and the rice plant, Oryza sativa, were collected from an agricultural site in the Middle East. Total As, its speciation and DNA fractionation were evaluated using HPLC-ICP-MS in samples which included the root, stem, leaf and grain of the rice plant. Methodology was validated through the use of CRMs. The highest concentration of As was found in the root of the plant and the lowest in the grain. The concentrations found for As were: soil (aqua-regia extractable; 2.88 μg g−1), irrigation water (0.58 μg L−1), roots (8.28 μg g−1), stem (4.00 μg g−1), leaves (2.93 μg g−1) and grain (1.02 μg g−1). Levels of inorganic AsV and AsIII were identified in the soil and plant material, while organo-arsenic species (DMA, MMA) were below the limit of detection. The ‘plant available’ levels of As in the soil (14%) were determined as part of a full, validated BCR three-step sequential extraction procedure. Since As can behave as a phosphate analogue, a method was developed for the extraction of vegetative DNA to determine the different forms of As associated with, or integrated within, the DNA fractions. Measurement of As in the DNA extracts were above the LOD (0.019 μg kg−1) for the root, stem and leaf samples. The concentration of both weakly and strongly associated As with DNA obtained from the root, stem and leaf decreased with decreasing total As concentrations. A narrow, near-constant ratio for the strongly associated As value (As/total As DNA) in all root, stem and leaf DNA samples (41.3 ± 0.3%) was further evidence for the incorporation of As into the DNA.

Enzymatic extraction methods were evaluated with classical extraction approaches for the determination of arsenic in food. The extraction efficiency for total arsenic was determined by analysing CRM materials DORM-3 fish protein, NIES 106 rice flour and GBW10015 spinach. These were compared with total arsenic concentration determined using microwave-assisted acid digestion and ICP-MS. The total arsenic concentrations in the CRM materials were in good agreement with the certified values. Enzymatic hydrolysis using trypsin has been successfully employed to extract arsenic species in DORM-3 and fish samples. Whilst this method of hydrolysing the proteins worked well for the fish samples, an alternative approach was required to facilitate the digestion of cellulose in plant materials. However, enzymatic extraction using cellulase was found to give unsatisfactory results for both the NIES and GBW10015 CRM materials. Dilute nitric acid (1% HNO3) was found to give a more efficient extraction for arsenic species in the same CRM materials and rice samples. The study was extended to evaluate a range of real samples. Total arsenic concentrations in 13 different types of fish tissue were determined following microwave-assisted acid digestion using nitric acid/hydrogen peroxide, followed by measurement using HPLC-ICP-MS for speciation analysis. The results obtained for fish were in the range of 3.53-98.80 µg g(-1) As (dry weight). Similarly, the results of 17 rice samples were in the range of 0.054-0.823 µg g(-1). This study demonstrates the importance of selecting an appropriate extraction technique for the quantitative measurement of arsenic species in food.

Element bioaccessibility in some nuts and seeds has been determined by performing a physiologically based extraction test. Nine elements (B, Ca, Co, Cu, Fe, Mn, Mg, Ni and Zn) in gastric and intestinal phase extractions of nuts and seeds were determined using inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. Hazelnuts, almonds, sunflower seeds, peanuts, cashew nuts, Brazil nuts, walnuts, chickpeas, pumpkin seeds and pistachio nuts were used as the materials in this study. The bioaccessible portions of magnesium and calcium were higher than for the other elements whereas B bioaccessibility was the lowest for each of the different types of nuts and seeds. Based on an ingestion rate of 10 g day−1, the amounts of B, Ca, Co, Cu, Fe, Mn, Mg, Ni and Zn from the nuts and seeds accessible to the body were found to be lower than the Tolerable Upper Intake Levels. The data were also subjected to chemometric evaluation using tools such as Principal Component Analysis (PCA) and Linear Discriminant Analyses (LDA) in an attempt to classify the nuts and seeds according to these elements bioaccessibility and to find out which elements are more bioaccessible in gastric and intestinal ingestions.

The aim of this study is to develop a new method for the extraction and preconcentration of trace elements from edible oils via an ultrasound-assisted extraction using ethylenediaminetetraacetic acid (EDTA) producing detergentless microemulsions. These were then analyzed using ICP-MS against matrix matched standards. Optimum experimental conditions were determined and the applicability of the proposed ultrasound-assisted extraction method was investigated. Under the optimal conditions, the detection limits (μg kg −1 ) were 2.47, 2.81, 0.013, 0.037, 1.37, 0.050, 0.049, 0.47, 0.032 and 0.087 for Al, Ca, Cd, Cu, Mg, Mn, Ni, Ti, V and Zn respectively for edible oils (3Sb/m). The accuracy of the developed method was checked by analyzing certified reference material. The proposed method was applied to different edible oils such as sunflower seed oil, rapeseed oil, olive oil and cod liver oil.

A new method for the extraction and preconcentration of trace elements (Al, Ba, Cd, Cu, Fe, Mn, Mo, Ni, Ti, V and Zn) from edible oils by producing detergentless micro-emulsions via an ultrasound-assisted extraction using a water phase containing Lipase at pH 3 as an extractant was developed. The trace elements in the water phase post-extraction were determined against matrix matched standards using ICP-MS. In the first step of the work, the parameters that affect extraction, such as pH, the volume of 1% lipase in the water phase and the ultrasonic and centrifugation times were optimized. Under the optimal conditions, the detection limits (µg kg(-1)) were 0.46, 0.03, 0.007, 0.028, 0.67, 0.038, 0.022, 0.14, 0.17, 0.05 and 0.07 for Al, Ba, Cd, Cu, Fe, Mn, Mo, Ni, Ti, V and Zn respectively for edible oils (3 Sb/m). A certified reference material (EnviroMAT HU-1 Used oil) was analysed to check the accuracy of the developed method. Results obtained were in agreement with certified values with a t-test showing that no significant differences at the 95% confidence levels were found. The proposed method was applied to different edible oils such as sunflower oil, rapeseed oil, olive oil and salmon oil.

This article reviews the nature of the flames employed in atomic absorption spectrometry (AAS), the features of the instrumentation used, and the atomization processes which take place within the flame. An overview of possible interferences and various modification that may provide some practical advantage over conventional flame cells is also included. Finally, a number of application notes for common matrices are presented.

A new, simple, efficient and rapid separation method based on ligandless-dispersive liquid–liquid microextraction (LL-DLLME) was developed for the preconcentration of rare earth elements (REEs) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in natural water samples, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. Carbon tetrachloride and acetone were used as extraction solvent and disperser solvent, respectively. The experimental parameters affecting the extraction efficiency such as sample pH, volume of extraction/disperser solvent and concentration of NaCl were investigated and optimized. Under the optimum conditions, detection limits between 0.68 and 26.6 ng L−1 for a 5 mL sample volume were determined. The developed method was successfully applied to samples such as tap water, river water and seawater. Satisfactory recoveries were obtained with the percentage recovery values of the REEs for spiked water samples being between 94 and 111 for tap water, between 89 and 118 for river water and between 92 and 124 for seawater.

Arsenic is ubiquitous in nature appearing in various chemical forms. The toxicity, environmental mobility and accumulation of As in living organisms depends on the form in which the element exists, thus requiring techniques which can identify specific forms whilst retaining their integrity during extraction and pre-treatment prior to measurement. Both organic and inorganic arsenic species may be present in food staples of both terrestrial and marine origin as well as natural waters, at sub ng l−1 to high mg l−1 levels. In this review, the speciation steps (sample preparation, species speciation and detection) most commonly used for the determination of As in food are described. High performance liquid chromatography separation with plasma source mass spectrometry is often the technique of choice due to its versatility, robustness and good detection limits. However, detection systems such as atomic absorption spectroscopy, atomic fluorescence spectrometry, and atomic emission spectrometry are also widely used and covered in this review together with some less utilised techniques.

An overview of the topics covered by, and the importance of, Atomic Spectrometry Updates.

Kara, Derya (Balikesir Author), A simple, easy to use and selective spectrofluorimetric method for the determination of trace levels of gallium has been developed. A new Schiff base, N-o-vanillidine-2-amino-p-cresol (OVAC) was synthesized and its fluorescence activity with gallium investigated. Based on this chelation reaction, a spectrofluorimetric method has been developed for the determination of gallium in synthetically prepared Ga-U and Ga-As samples buffered at pH 4.0 using acetic acid-sodium acetate. The chelation reaction between Ga(III) and N-o-vanillidine-2-amino-p-cresol was very fast, requiring only 30 min at room temperature to complex completely. The limit of detection (LOD) (3 sigma) for Ga(III) was 7.17 nM (0.50 mu g L(-1)), determined from the analysis of 11 different solutions of 20 mu g L(-1) Ga(III). (C) 2009 Elsevier B.V. All rights reserved.

Kara, Derya (Balikesir Author), An on-line flow injection spectrofluorimetric method for the direct determination of aluminium in water samples is described. The method is based on the reaction of aluminium with N-o-vanillidine-2-amino-p-cresol (OVAC) in acidic medium at pH 4.0 to form a watersoluble complex. The excitation and emission wavelengths were 423.0 and 553.0 nm, respectively, at which the OVAC-Al complex gave the maximum fluorescence intensity at pH 4.0 in a 50% methanol-50% water medium at 50 degrees C. An interference from fluoride ions was minimised by the addition of Be2+. Other ions were found not to interfere at the concentrations likely to be found in natural waters. The proposed methods were validated in terms of linearity, repeatability detection limit, accuracy and selectivity. Under these conditions, the calibration was linear up to 1000 mu g L-1 (r=0.999). The limit of detection (3 sigma) for the determination of Al(III) was 0.057 mu g L-1 and the precision for multiple determinations of 3 ng mL(-1) Al(III) prepared in ultra-pure water was found to be 0.62% (n=10). The Schiff base ligand could be used to determine ultra-trace aluminium from natural waters. Analysis of environmental certified reference materials showed good agreement with the certified values. The procedure was found to be equally applicable to both fresh-water and saline solutions, including seawater.

Samples of soil, the broad bean plant, Vicia faba and irrigation water were collected from the same agricultural site in Dokan, in the Kurdistan region of Iraq. Total arsenic and arsenic speciation were determined in all materials by ICP-MS and HPLC-ICP-MS, respectively. Available arsenic (11%) was also determined within the soil, together with Cd, Cr, Cu, Ni, Zn, Fe and Mn. The concentrations of total arsenic were: soil (5.32μgg(-1)), irrigation water (1.06μgL(-1)), roots (2.065μgg(-1)) and bean (0.133μgg(-1)). Stems, leaves and pods were also measured. Inorganic As(V) dominated soil (90%) and root (78%) samples. However, organo-arsenic (MMA, 48% and DMA, 19%) was the more dominant species in the edible bean. The study provides an insight into the uptake, preferred disposal route, speciation changes and loss mechanism involved for arsenic with this food source.

A study of the trace metal distribution in sediment samples from the Galician coast (Spain) has been performed. A multielement extraction method optimised via experimental design has been employed. The method uses centrifugation to pass the extractant solution at varying pH, through the sediment sample. The sequential leaches were collected and analysed by ICP-AES. Chemometric approaches were utilised to identify the composition of the physico-chemical components in order to characterise the sample. The samples collected at different sites could be classified according to their differences in metal bio-availability and important information regarding element distribution within the physico-chemical components is given. The method has proved to be a quick and reliable way to evaluate sediment samples for environmental geochemistry analysis. In addition, this approach has potential as fast screening method for the bio-availability of metals in the environment.

An environmentally friendly and simple method has been developed for complete digestion of lead, cadmium and antimony from soil samples using a magnesium nitrate assisted dry ashing procedure. Statistical data for a series of experiments with standard reference materials are presented, and precision values are found to be comparable for inductively coupled plasma-mass spectrometry and for inductively coupled plasma-atomic emission spectrometry. From a single digest solution all analytes are quantified without involving any pre-concentration routes. Inter-method comparison of inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) shows that the probability of the results being different is less than 99%.

Studies on nitrogen in natural waters have generally focussed on dissolved inorganic nitrogen (DIN), primarily because of relative ease of analysis and the important influence of DIN on water quality. Advances in analytical techniques now permit the systematic study of dissolved organic nitrogen (DON), and this work has shown that DON is quantitatively significant in many waters. This article describes the sampling and analytical protocols required for rapid, precise and reliable determinations of DON, involving high-temperature catalytic oxidation (HTCO), coupled to chemiluminescence detection. This approach simultaneously determines dissolved organic carbon (DOC) and total dissolved nitrogen (TDN), and DON is derived by subtraction of DIN measured by colorimetry. The DON determination is simple to perform, exhibits excellent precision (

Trace metals in tea originating from various Asian and African countries were determined by using inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. Pattern recognition techniques were then used to classify the tea according to its geographical origin. Principal component analysis (PCA) and cluster analysis (CA), as exploratory techniques, and linear discriminant analysis (LDA) and soft independent modelling of class analogy (SIMCA), were used as classification procedures. In total, 17 elements (Al, Ba, Ca, Cd, Co, Cr, Cu, Cs, Mg, Mn, Ni, Pb, Rb, Sr, Ti, V, Zn) were determined in a range of 85 tea samples (36 samples from Asian countries, 18 samples from African countries, 24 commercial blends and seven samples of unknown origin). Natural groupings of the samples (Asian and African teas) were observed using PCA and CA (squared Euclidean distance between objects and Ward's method as clustering procedure). The application of LDA gave correct assignation percentages of 100.0% and 94.4% for the African and Asian teas, respectively, at a significance level of 5%. SIMCA offered percentages of 100.0% and 91.7% for African and Asian groups, respectively, at the same significance level. LDA, also at a significance level of 5%, allowed a 100% of correct case identification for the three classes China, India and Sri Lanka. However, a satisfactory classification using SIMCA was only obtained for the Chinese teas (100% of cases correctly classified), while teas from India and Sri Lanka appear to form the same class.

The optimisation of a simple multielement extraction method employing an experimental design approach is described. The method uses centrifugation to pass one extractant solution at varying pH through a contaminated soil sample. The nature and concentration of the acid, rate of centrifugation and time, number of sequential leachates and the ratio of extractant volume: sample weight have been studied in order to obtain the optimum conditions for extraction. A fractional factorial experimental design was performed, and the results were used to identify significance which was then evaluated by carrying out a central composite experimental approach. Once optimum conditions had been obtained, sequential leaches were analysed by ICP-AES and chemometrics were employed to identify the composition of each component. Comparisons have been made with previous studies and tentative assignments, based on well defined separated fractions and percentage compositions for individual elements, used to identify the different physico-chemical components in the sample.

Fisher, Derya Kara (Balıkesir author), Seventeen trace metals in acid digests of nuts and seeds were determined using inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry. The data were subjected to chemometric evaluation using principal component analysis (PCA), linear discriminant analysis (LDA) and cluster analysis (CA) in an attempt to classify the samples. Hazelnuts (raw and dry roasted), almonds (raw and dry roasted), sunflower seeds (black and white), peanuts (raw and dry roasted), cashew nuts, Brazil nuts, walnuts, chickpeas (raw and dry roasted), pumpkin seeds (raw and dry roasted), and pistachio nuts were used as samples. The samples were classified into seven groups by PCA and CA. All group members determined using PCA and CA were found by LDA to be correctly classified in the predicted groups. Interestingly, the chemometric evaluation indicated that the raw and roasted nuts are very close to each other even though some originated from different countries., Unit of the Scientific Research Projects of Balikesir University 2012/sixty

A method has been developed for the speciation of arsenic in a variety of baby foods using directly coupled high performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS). Ion exchange HPLC separation using gradient elution and sodium sulphate as the mobile phase resulted in good resolution and a fast separation of the following species: arsenobetaine, monomethylarsonic acid, dimethylarsinic acid and arsenate. The arsenicals were extracted by two enzymatic digestion procedures, based on the action of trypsin or pancreatin. The results from the enzyme digested samples were compared with those obtained for “total” arsenic by microwave-oven digestion. The reliability of the procedure was also checked by analysing the total reducible arsenic species by hydride generation-AAS and by analysing two certified reference materials. The enzymatic digestion procedures were also evaluated on pure standards to ensure that no species alteration occurred during the extraction process. Trypsin was found to work well although the pancreatin extraction had a deleterious effect on the chromatography, with the dimethylarsinic acid peak co-eluting with the arsenobetaine. Pancreatin was therefore concluded to be unsuitable for the speciation process, although the total amount of arsenic extracted was comparable to the trypsin extraction. Values for the total arsenic content in the baby foods were found to range between 0.25 and 4.7 μg g −1 . Arsenobetaine was the only arsenic species detected in most samples, but an unidentified species was detected in one sample.

An on-line solid-phase extraction method, linked to inductively coupled plasma mass spectrometry has been developed to overcome the problems of a high sample matrix concentration interfering with the determination of low levels of uranium and thorium in aqueous samples. Using an actinide-specific extraction resin (TRU-spec), in a small column incorporated into the sample introduction manifold, recovery of the analytes (U101−108%, 87 Th 115%) was obtained from seawater (NASS-4 seawater CRM, 2.68 ng ml−1 U), ground water (0.1 ng ml−1 U in 3000 μg ml−1 total dissolved solids) and samples containing significant levels of dissolved organic carbon (1 ng ml−1 U/Th, 8 μg ml−1 humic and fulvic acids). This is an improvement on conventional ion exchange and chelating resins which give low recoveries in the presence of dissolved organic carbon. The samples were injected directly on to the column, with no prior dilution. Figures-of-merit obtained were R2: U 0.998, Th 0.999, for 0 to 10 ng ml−1, R.S.D.: U 4.3%, Th 5.8%, and limits of detection: U 0.015 ng ml−1 and Th 0.006 ng ml−1 in a synthetic seawater matrix.

This paper describes the application of a trilinear parallel factor analysis (PARAFAC) to study systematic error during the multi-element determination of a range of analytes in acid digests of solid samples (tea leaves) by ICP-AES and ICP-MS. The three variables studied were the “number of digestions”, in order to assess the systematic error associated with the sample pre-treatment, and the “number of replicates” and “calibration”, to provide information on the systematic error associated with the analytical determination itself. The elements under study were Co, Cr, Cu, Ni, Pb, Rb and Ti by ICP-MS, and Ba, Ca, Fe, Mg, Mn, Sr and Zn by both ICP-MS and ICP-AES. For some elements flame atomic absorption spectrometry was used for comparative purposes. A Chinese tea certified reference material containing many of the metals above was used in the study. The results obtained were compared to results from ANOVA. It was found that the systematic error, expressed as the sum of squares after PARAFAC, was quite different from the results obtained using ANOVA due to the very different way in which the models are built. The PARAFAC approach is shown to be straightforward to implement and robust.

Systematic errors observed when using inductively coupled plasma atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) for the multi-element determination in acid digests of environmental samples (tea leaves) were evaluated. Two chemometric approaches, experimental design and principal component analysis, were used in order to establish the errors associated with each stage of the analytical method: sample digestion (effect of the “number of acid digestions”) and measurement step (effect of the “number of replicates” and the “calibration”). The elements under study were Co, Cr, Cs, Cu, Ni, Pb, Rb and Ti by ICP-MS, and Ba, Ca, Fe, Mg, Mn, Sr and Zn by ICP-MS and ICP-AES. Flame atomic absorption spectrometry was used for comparative purposes. A Chinese tea certified reference material with certified concentration for most of the elements was employed as the sample matrix. Variance estimation was made from ANOVA outputs from a full factorial design (FFD) 41 × 41 × 21.

Although major advantages have been made in developing robust, easy-to-use ICP-AES instruments offering sub µg g−1 detection limits and relative interference free operation, long-term drift of the analytical signal continuous to be problematic and necessitates regular re-calibration. The work presented here focuses on the effect of two instrumental parameters, i.e. the rf power and the nebuliser gas flow rate, on the robustness of the signals. The effects on the long-term stability when varying these two factors was systematically studied using an experimental design protocol. A 'drift diagnosis' on thirty emission lines was performed at 12 different sets of operating conditions by repeated determination of a multi-element solution over several hours. The results were studied using standard parameters, i.e., Mg ratio, sensitivity, drift error, drift patterns and multi-way analysis. Parallel factor analysis (PARAFAC) was employed to analyse the 3-way data array generated: 'emission lines × replicates × operating conditions'. The physical interpretation of the new PARAFAC-factors is shown to enable a better understanding of the drift phenomenon by mathematically characterising the causes of long-term instability. Finally, the robustness of the technique using different operating conditions is evaluated and the appropriate use of internal standards to correct for drift is discussed.

A simple transformation that uses the half-range and central value has been used as a data pre-treatment procedure for principal component analysis (PCA) and pattern recognition techniques. The results obtained have been compared with the results from classical normalisation of data (mean normalisation, maximum normalisation and range normalisation), autoscaling and the minimum–maximum transformation. Three data sets were used in the study. The first was formed by determining 17 elements in 53 tea samples (901 pieces of data). The second and third data sets arose from two long-term drift studies performed to examine instrumental stability at standard and robust conditions. The instruments used were an inductively coupled plasma atomic emission spectrometer and an inductively coupled plasma mass spectrometer. Each drift diagnosis experiment consisted of replicate determinations of a test solution containing 15 analytes at 10 mg l−1 over 8 h without recalibration. Twenty-nine emission lines were determined 99 times, thus, each data set was formed by 2881 pieces of data. Data pre-treatment was applied to the three data sets prior to the use of principal component analysis, cluster analysis, linear discrimination analysis and soft independent modelling of class analogy. The study revealed that the half-range and central value transformation resulted in a better classification of the tea samples than that achieved using the classical normalisation. The loadings in the PCA for the long-term stability study, under both standard and robust conditions, were found to be similar to the drift trends only when the minimum–maximum transformation and the mean or maximum normalisations were used as data pre-treatments.

Chelation ion chromatography, involving a high efficiency neutral polystyrene-divinylbenzene resin dynamically coated with 2,6-pyridinedicarboxylic acid, has been developed as a novel technique for the quantitative determination of uranium in complex matrices. An isocratic separation method, using an eluent consisting of 1M KNO3, 0.5M HNO3 and 0.1 mM 2,6-pyridinedicarboxylic acid, allowed the uranyl ion to elute away from matrix interferences in under ten minutes. Detection was achieved using an Arsenazo III post column reaction system. Good recoveries were obtained from spiked mineral water and sea water and the standard addition curves produced good linearity (r2>0.997) with a detection limit, calculated as twice baseline noise, of 20 μg L−1. The procedure was applied to the determination of trace uranium in standard reference water and sediment samples. The results obtained compared well with the certified values for uranium.

High-performance liquid chromatography–isotope dilution inductively coupled plasma mass spectrometry (HPLC–ID-ICP-MS) provides the coupling of two established instrumental techniques to achieve accurate and precise measurements. The approach offers considerable potential for speciation studies. On its own, isotope dilution is regarded as being a definitive technique that overcomes many problems associated with instrumental drift and incomplete extraction of analytes from samples. These advantages are also inherent in HPLC–ID-ICP-MS although the technique does require isotopically pure standards and cannot overcome problems associated with speciation changes and contamination. This overview describes the procedures used and the requirements necessary to achieve accurate and reliable results when using HPLC–ID-ICP-MS and outlines the application of this technique to speciation studies on tin and lead. A short review of other work published in this area is also presented.

A method is reported for correction of long-term drift in ICP-AES measurements. The change in the intensity of thirty emission lines was monitored over eight hours without recalibration of the instrument. Drift values were found to give errors of up to 20% with respect to the first measurement. The suggested procedure utilises the drift pattern of an intrinsic plasma line, Ar 404.597 nm, and the results of a principal component analysis to remove the drift error. After correction, the drift values drop to less than ±2%.

A procedure for the determination of selenium in water and serum using electrothermal vaporisation isotope dilution inductively coupled plasma mass spectrometry (ETV-ID-ICP-MS) is described. The 82Se∶77Se isotope ratio was measured throughout, following spiking of the samples with a solution containing the enriched 77Se isotope. Elimination of interferences was achieved with an optimised ETV temperature program. Parameters such as peak measurement mode, dwell time, points per spectral peak and number of replicates were evaluated to establish optimum conditions. The accuracy and precision of the method are demonstrated with the analysis of several certified reference materials namely TMRAIN-95 (spiked rainwater), TMDA-54.2 (spiked soft water), LGC 6010 (hard drinking water) and NIST 1598 (bovine serum). Results for all reference materials were within the certified limits. Isotope dilution analysis of TMRAIN-95, TMDA-54.2, LGC 6010 and NIST 1598 gave % RSD values (n = 3) of 0.80, 0.07, 0.48 and 0.06%, respectively, compared with 5.50, 2.79, 1.15 and 0.92% obtained with the conventional ETV-ICP-MS procedure, thus illustrating improvements in precision with the ETV-ID-ICP-MS method. The uncertainties for the two methods were calculated following ISO guidelines. The uncertainty for the IDMS procedure was 3.4 times smaller than that for the conventional ETV-ICP-MS method (2.26% and 7.73%, respectively).

This study shows that stable high efficiency metal chelating substrates can be formed from neutral stationary phases by dynamically loading with low molecular weight complexing agents present in the mobile phase. Three complexing pyridine carboxylic acids, namely, picolinic, dipicolinic and quinaldic acids were used to dynamically coat both a C18silica gel and a polystyrene resin and the separation performance compared for groups of metal ions. Quinaldic acid gave the largest selectivity coefficients as it produced the most concentrated coating, while picolinic acid was too weakly adsorbed to give any significant metal retention apart from copper. Dipicolinic acid was found to be especially selective for uranium(VI). In general, retention order was the same on both stationary phases, but the polystyrene resin produced the most efficient separations. Interesting selectivity differences were found between the different acid coatings. For example, for dipositive ions, the retention order using a dipicolinic acid coating was Mn(II)

The growth of Fucus vesiculosus L, germlings in chemically defined culture media containing a range of Cu concentrations (20-1000 nM) was monitored simultaneously with measurement of the Cu speciation in the media by competitive equilibrium-adsorptive cathodic stripping voltammetry, Fucus vesiculosus germlings were found to exude Cu-complexing Ligands with conditional stability constants of the order of 1.6 x 10(11), Ligand concentrations increased with increasing total dissolved Cu concentrations (Cu-T) until a concentration of 500-800 neq Cu.L-1 was reached. Concentrations of the ligand exceeded Cu-T in treatments containing 20 and 100 nM Cu-T were similar to Cu-T in the 500-nM Cu treatment, but were less than Cu-T in the 1000-nM treatment. Therefore, [Cu2+] were calculated to be at concentrations of 10(-11) - 10(-10) M in the 20- and 100-nM treatments, 10(-9) M in the 500-nM treatment, and 10(-7) M in the 1000-nM treatment, Growth rates were lowest at Cu2+ concentration > 10(-9). These results are discussed within the context of the potential roles for exuded copper-complexing ligands

A simple but robust battery powered field sampling unit for the selective in situ preconcentration of trace elements (Cd, Co, Cu, Mn, Ni, Pb and Zn) from natural waters on a commercially available iminodiacetate resin is described. Water samples were filtered (0.45 μm) on-line and passed through twin microcolumns containing the resin Metpac CC-1. This allowed duplicate samples to be preconcentrated in parallel. The microcolumns were then taken to the laboratory and placed in a flow injection manifold coupled to an inductively coupled plasma – atomic emission spectrometer (FI – ICP–AES) for elution and quantitation. The results for CASS-2, a coastal seawater CRM, preconcentrated for 2 h at 0.5 ml min−1, gave good agreement with certified values for Cd, Co, Cu, Mn, Ni and Zn. The preconcentration column has been shown to be applicable to samples in the salinity range 39–156% for Cd, Co, Mn and Zn and the field sampling unit is therefore suitable for the analysis of seawaters and industrial brines (...

The chromatographic behavior of alkaline earth metals, Cu(II), Mn(II), Co(II), Zn(II), Ni(II), Pb(II), and Cd(II) on a chelating aminomethylphosphonic acid-functionalized silica column was studied in eluants with high ionic strength to suppress ion exchange. Unusual variations were found in plots of capacity factor against pH demonstrating changes in retention order, suggesting a change in the coordination of metal ions from O,O to N,O,O chelation. Increased affinity of the chelating ion exchanger to heavy metals and in particular Mn(II) was observed at low pH. Examples are shown of high-efficiency separations of groups of metal species with varying retention orders at different pH values, including a separation of eight metal species in under 16 min. These characteristics make aminophosphonate chelating substrates a useful and more versatile phase for high-performance chelation ion chromatography than iminodiacetate phases.

The preconcentration, separation and determination of Cr III and Cr VI have been achieved by using a combination of ion exchange media and energy dispersive X-ray fluorescence (EDXRF) spectrometry. The species in aqueous solution have been retained sequentially on activated alumina and Dowex 1-X8 for Cr VI and three different cation exchangers, Dowex 50W-X8, Zerolite and activated alumina, for Cr III and then determined directly on the adsorption media. The results obtained show that the Dowex resins are the best for the speciation of chromium in waters. The use of these resins allows linear ranges of over three orders of magnitude and a reduction of those matrix effects so often observed in EDXRF. The method was tested using a 100-fold diluted Ground Water and Waste Water Pollution Control Check Standard WP-15 which contains Cr III and was spiked with Cr VI . Full recoveries were achieved from this standard with precision values of 4% or less. The detection limits obtained for a preconcentration factor of 50 were 0.3 mg l –1 for Cr VI on Dowex 1-X8 and 0.4 mg l –1 for Cr III on Dowex 50W-X8. These limits were reduced to 0.03 and 0.04 mg l –1 , respectively, if a 500-times preconcentration factor was employed. The scope of the method was investigated further by analysing spiked samples of local natural waters (river and sea) for both Cr III and Cr VI species directly. While the advantages of using this methodology are clearly seen, some limitations are noted for samples of high saline content.

The development of a novel procedure for the accurate determination of selenium in serum using electrothermal vaporisation inductively coupled plasma mass spectrometry (ETV-ICP-MS) is described. The proposed method eliminates the need for a lengthy sample digestion procedure (a requirement with many methods for the analysis of biological samples), utilising a simple 1+19 dilution of the serum with 1% nitric acid. Many of the interferences normally associated with the determination of selenium by ICP-MS are successfully eliminated with careful optimisation of the ETV temperature program and modifier system. Analytical characteristics for 74 Se, 77 Se, 78 Se and 82 Se are reported, including detection limits (3σ blank) of approximately 0.1 ng g –1 for 77 Se and 82 Se. Short- and long-term reproducibility data between 4.7 and 4.9% and 3.2 and 3.8% (RSD) for 77 Se and 82 Se, respectively, are shown. The accuracy of the method, which included Te as an internal standard, was demonstrated with the analysis of three internal quality control samples and the certified reference material NIST SRM 1598 (bovine serum). Results within 10% of the target value were achieved for three of the four isotopes studied, with slightly worse results for 78 Se owing to the large interference from argon adduct ions on this isotope. Preliminary work involving the addition of nitrogen to the argon aerosol carrier gas was successful in reducing the ArAr interference at m/z 78.

A simultaneous multi-element approach utilising “in-atomiser trapping” electrothermal atomic absorption spectrometry (ETAAS) for As, Bi, Sb and Se was developed. The approach uses flow injection methodology and hydride formation with sodium tetrahydroborate to sequestrate the hydrides of the elements of interest on an Ir pre-coated graphite tube. Since the efficiency of the hydride formation depends on the oxidation state of the analyte, an off-line reduction process was included to ensure that the analyte to be determined was in the most sensitive and favourable oxidation state. Initially five elements, As, Bi, Sb, Se and Te, were considered for simultaneous “in-atomiser trappin”'. The elements were split into two groups reflecting the nature of the reducing agent required by each of the elements. Group A consisted of As, Bi and Sb and used l-cysteine as the reducing agent, whilst Group B consisted of Bi, Se and Te and used concentrated HCl as the reducing agent. However, Te was later removed from Group B due to problems in identifying a set of compromise conditions which enabled all three elements to be determined simultaneously. Bismuth featured in both groups as it did not require a reduction step. Various tube coatings were considered and Ir and Zr were evaluated. Iridium was found to be well suited to this application. The characteristic masses obtained using this method were 177, 91, 107 and 90 pg for As, Bi, Sb and Se, respectively, yielding detection limits (500 µl sample loop) of 0.82, 0.04, 0.26 and 0.29 µg l –1 . Precision for analytes at the 5 µg l –1 level was typically better than 3.5% RSD. The method was validated by the analysis of two Certified Reference Materials and good agreement was found with the certified values.

Organotin compounds are known to be toxic to several organisms, including human beings. Their use has been widely extended recently. Thus, several methods have been developed to separate and determine these species. This article reviews the properties of organic species of tin and the high-performance liquid chromatographic methods proposed for their determination.

A new method for lead speciation in rainwater by isotope dilution analysis (IDA) using directly coupled high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) is described and demonstrated. Samples containing trimethyllead (TML) chloride and triethyllead (TEL) chloride in the presence of large amounts of inorganic lead have been analysed by HPLC-ICP-MS using reverse phase ion-pairing chromatography. The detection limit for the procedure is 3 ng g−1 for TML as Pb and 14 ng g−1 for TEL as Pb, with a linear range exceeding 1000 ng g−1 and a relative standard deviation of 4% for TML in the range 50–1000 ng g−1. TML chloride isotopically enriched in the stable 206 isotope was prepared and used to enhance the accuracy of the method by isotope dilution analysis. The IDA-HPLC-ICP-MS method was successfully applied to the analysis of a sample of artificial rainwater used in a collaborative study.

A preliminary study to classify tea by geographical origin using trace metal concentrations was made. Fifteen types of tea from ten different countries were digested using nitric acid. The digests were then analysed for their trace metal contents using either inductively coupled plasma-atomic emission spectrometry for the more concentrated analytes (Al, Ba, Ca, Cu, Fe, La, Mg, Mn, Sr, Ti and Zn) or inductively coupled plasma mass spectrometry for the less concentrated analytes (Cd, Co, Cr, Cs, Hg, La, Li, Nd, Ni, Pb, Pr, Rb, Se, Sn, Ti, V and Zr). The data obtained from these results were then analysed using UNSCRAMBLE, a chemometrics package that incorporates principal component analysis, and by using Matlab 4.2cl High Performance Numeric Computation and Visualisation software. The results of the chemometrics analysis indicated that a distinction between African and Asian and between Chinese and other Asian teas could be made.

A method for the determination of trace bismuth in lead using a high-performance chelating ion chromatography (HPCIC) system is described. A novel high-efficiency chelating column was prepared from a neutral hypercrosslinked polystyrene resin, MN200 (Purolite). It was found that the unmodified material had metal complexing properties similar to resins containing immobilized chelating dyestuffs. The resin was very stable in strong acid conditions and was therefore suitable for the investigation of metal ions with high positive charge. Bismuth was eluted with good peak shapes using halogen acids. Hydrobromic acid was chosen as it gave more sensitive detection than hydrochloric acid. Detection was carried out by direct UV–Vis absorption measurement of the bismuth bromide complex so no post-column reaction system was required. No interference was observed from lead halides at 370 nm. A certified lead reference material (CRM 288B) was used to successfully validate the method. The detection limit for bismuth was found to be 10 μg l−1 and analysis times were less than 5 min from the time of injection.

A flow injection procedure with detection by inductively coupled plasma-mass spectrometry (ICP-MS) for the on-line matrix elimination and preconcentration of five elements (Cd, Co, Cu, Mn and Pb) from natural waters on a commercially available iminodiacetic acid resin is described. The results for the certified reference materials (CRMs) NASS-2 (an open ocean seawater) and SLRS-2 (a river water) gave good agreement with certified values. Recoveries from seawater were in the range 95–111% with relative standard deviations (RSDs) (n = 5) in the range 5–8%. The efficiency with which the major matrix cations (Ca2+, K+, Mg2+ and Na+) were removed has also been investigated and the importance of using suitable buffers and concentrations for the efficient removal of all of these cations with minimal reagent contamination is highlighted. The application of this column system for in-situ preconcentration is also discussed (with preconcentration factors of up to 120X) and Mn (selected as a model element) has also been quantified in SLRS-2 by flow injection-flume atomic absorption spectrometry (FI-FAAS) using 15 min preconcentration. This shows that the method can be used effectively with both flame and plasma detection.

The gas-phase molecular absorption spectrometric method for determining sulfide was applied to the determination of sulfide in waste water using a fully automated system. The instrumentation utilizes a commercially available vapour generator and an absorption cell placed in the optical path of an atomic absorption spectrometer set at 200 nm. A sulfide anti oxidant buffer (SAOB) consisting of sodium hydroxide (0.5 mol l - 1 ), sodium tetrahydroborate (0.2 mol l - 1 ) and sodium citrate (0.2 mol l - 1 ) was found to have advantages in terms of shelf-life over existing SAOB formulations. A gas–liquid separator was designed that also assisted in the transport of the hydrogen sulfide, generated by hydrochloric acid (0.6 mol l - 1 ), to the absorption cell. The limit of detection was 0.13 mg l - 1 of sulfide and the calibration was linear up to 100 mg l - 1 . Of 16 ions tested for interference, at a 50-fold excess, only copper, lead, zinc and arsenic gave serious interference problems. The method was applied to the determination of sulfide in waste waters and good agreement was found with the stabilized iodine titration procedure. Spike recoveries from the waste water ranged between 97 and 101%. Unattended operation allowed the analysis of up to 90 samples per hour.

A simple and accurate method has been developed for the determination of total mercury in environmental and biological samples. The method utilises an off-line microwave digestion stage followed by analysis using a flow injection system with detection by cold vapour atomic absorption spectrometry. The method has been validated using two certified reference materials (DORM-1 dogfish and MESS-2 estuarine sediment) and the results agreed well with the certified values. A detection limit of 0.2 ng g −1 Hg was obtained and no significant interference was observed. The method was finally applied to the determination of mercury in river sediments and canned tuna fish, and gave results in the range 0.1–3.0 mg kg −1 .

A system capable of the separation of arsenic species by on-line high performance liquid chromatography prior to their online decomposition by microwave digestion, pre-reduction with l -cysteine and analysis by hydride generation-atomic absorption spectrometry has been developed. This approach enables the full speciation of arsenobetaine, monomethylarsonic acid, dimethylarsinic acid and total inorganic arsenic (arsenite + arsenate) in biological samples. Simple modification of the system allows for the determination of the total arsenic content of the sample. In addition quantification of the total reducible arsenic species (arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid) can be achieved by on-line prereduction-hydride generation-atomic absorption spectrometry. Procedures were validated by analysis of the certified reference materials NRCC DORM-1 and TORT-1 and gave results in good agreement with the certified values.

The following paper describes the comparison of a number of dye impregnated polystyrene resins and dye coated cellulose for the chelating ion exchange of metal ions. Dye loadings, capacity factors, metal adsorption capacity and selectivities were measured. The cellulose substrate was found to have a strong affinity for copper but had a very low capacity. Of the polysterene resins, highly cross-linked macronets gave the highest metal adsorption capacities. For one of the resins, an example of a separation of a synthetic mixture of alkaline earth metals in high ionic strength media is described.