Environmental application of elemental speciation analysis based on liquid or gas chromatography hyphenated to inductively coupled plasma mass spectrometry—A review

SERSomes for metabolic phenotyping and prostate cancer diagnosis

Molecular phenotypic variations in metabolites offer the promise of rapid profiling of physiological and pathological states for diagnosis, monitoring, and prognosis. Since present methods are expensive, time-consuming, and still not sensitive enough, there is an urgent need for approaches that can interrogate complex biological fluids at a system-wide level. Here, we introduce hyperspectral surface-enhanced Raman spectroscopy (SERS) to profile microliters of biofluidic metabolite extraction in 15 min with a spectral set, SERSome, that can be used to describe the structures and functions of various molecules produced in the biofluid at a specific time via SERS characteristics. The metabolite differences of various biofluids, including cell culture medium and human serum, are successfully profiled, showing a diagnosis accuracy of 80.8% on the internal test set and 73% on the external validation set for prostate cancer, discovering potential biomarkers, and predicting the tissue-level pathological aggressiveness. SERSomes offer a promising methodology for metabolic phenotyping.

Novel approach to supercritical fluid chromatography-mass spectrometry analysis of metal ions using EDTA complexation

BACKGROUND

Reliable methods enabling detection of metal ions, and especially heavy metals, in different matrices are necessary in various fields such as ecology, pharmaceuticals and toxicology. As some of the currently used methods suffer from spectral and chemical interferences, this study investigates the applicability of SFC-MS/MS for the determination of metal ions.

RESULTS

Effective novel approaches for metal ion analysis using CO2-based mobile phase were developed using three ligands forming metal complexes. As metal-EDTA complexes are prepared by simple addition of EDTA to the solution containing metal ions, this approach to metal ion analysis does not require laborious synthesis and isolation of solid metal-complexes. Besides, two other approaches using diethyldithiocarbamate and acetylacetonate as ligands were compared. Metal complexes of Cu, Co, Cr, Fe, Al, Mn, and Zn with all 3 ligands were synthesized and their identity was confirmed by high-resolution mass spectrometry (HRMS). The suitability of the three developed UHPSFC-MS/MS methods was examined using the determination of calibration range and repeatability of injections. Moreover, the universality of the developed UHPSFC-MS/MS method for the determination of metal-EDTA complexes was proved by analyzing Ni, Bi and Pb as additional metal ions.

SIGNIFICANCE AND NOVELTY

This study demonstrates the extended range of applicability for SFC based separations. For the first time, the possibility to analyze metal complexes with EDTA using a fast and reliable ultra-high performance supercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) method is reported. The three developed UHPSFC-MS/MS methods are able to separate DDC, acac, and EDTA complexes of various metals very efficiently (total cycle times of 5, 2, and 3 min, respectively). They offer a fast and green alternative to chromatographic methods commonly used for metal ion analysis.

Online Sequential Determination of Organic/Inorganic Lead Speciation in PM2.5 Using Electrochemical Mass Spectrometry

The information regarding the occurrence and abundance of lead (Pb) in PM2.5 is useful for the evaluation of air pollution status and tracing the pollution source. Herein, electrochemical mass spectrometry (EC-MS) for sequential determination of Pb species in PM2.5 samples without sample pretreatment has been developed using the combination of online sequential extraction with mass spectrometry (MS) detection. Four kinds of Pb species including water-soluble Pb compounds, fat-soluble Pb compounds, water/fat-insoluble Pb compounds, and a water/fat-insoluble Pb element were sequentially extracted from PM2.5 samples, in which water-soluble Pb compounds, fat-soluble Pb compounds, and water/fat-insoluble Pb compounds were extracted sequentially by elution using H₂O, CH₃OH, and EDTA-2Na as the eluent respectively, while the water/fat-insoluble Pb element was extracted by electrolysis using EDTA-2Na as the electrolyte. The extracted water-soluble Pb compounds, water/fat-insoluble Pb compounds, and water/fat-insoluble Pb element were transformed into EDTA-Pb in real time for online electrospray ionization mass spectrometry analysis, while the extracted fat-soluble Pb compounds were directly detected by electrospray ionization mass spectrometry. The advantages of the reported method include the obviation of sample pretreatment, high speed of analysis (<60 min/sample), low detection limit (0.16 pg), low sample consumption (30 μg), and high accuracy (>90%), which indicates the potential of this method for the rapid quantitative species detection of metals in environmental particulate matter samples.

A review on arsenic in the environment: contamination, mobility, sources, and exposure

Arsenic is one of the regulated hazard materials in the environment and a persistent pollutant creating environmental, agricultural and health issues and posing a serious risk to humans. In the present review, sources and mobility of As in various compartments of the environment (air, water, soil and sediment) around the World are comprehensively investigated, along with measures of health hazards. Multiple atomic spectrometric approaches have been applied for total and speciation analysis of As chemical species. The LoD values are basically under 1 μg L-1, which is sufficient for the analysis of As or its chemical species in environmental samples. Both natural and anthropogenic sources contributed to As in air, while fine particulate matter tends to have higher concentrations of arsenic and results in high concentrations of As up to a maximum of 1660 ng m-3 in urban areas. Sources for As in natural waters (as dissolved or in particulate form) can be attributed to natural deposits, agricultural and industrial effluents, for which the maximum concentration of 2000 μg L-1 was found in groundwater. Sources for As in soil can be the initial contents, fossil fuel burning products, industrial effluents, pesticides, and so on, with a maximum reported concentration up to 4600 mg kg-1. Sources for As in sediments can be attributed to their reservoirs, with a maximum reported concentration up to 2500 mg kg-1. It is notable that some reported concentrations of As in the environment are several times higher than permissible limits. However, many aspects of arsenic environmental chemistry including contamination of the environment, quantification, mobility, removal and health hazards are still unclear.

The importance and status of the micronutrient selenium in South Africa: a review

Selenium (Se) is a vital micronutrient with widespread biological action but leads to toxicity when taken in excessive amounts. The biological benefits of Se are mainly derived from its presence in active sites of selenoproteins such as glutathione peroxidase (GPx). An enzyme whose role is to protect tissues against oxidative stress by catalysing the reduction of peroxidase responsible for various forms of cellular damage. The benefits of Se can be harvested when proper regulations of its intake are used. In South Africa, Se distribution in people's diets and animals are low with socio-economic factors and heterogeneous spread of Se in soil throughout the country playing a significant role. The possible causes of low Se in soils may be influenced by underlying geological material, climatic conditions, and anthropogenic activities. Sedimentary rock formations show higher Se concentrations compared to igneous and metamorphic rock formations. Higher Se concentrations in soils dominates in humid and sub-humid areas of South Africa. Furthermore, atmospheric acid deposition dramatically influences the availability of Se to plants. The studies reviewed in this article have shown that atomic absorption spectroscopy (AAS) is the most utilised analytical technique for total Se concentration determination in environmental samples and there is a lack of speciation data for Se concentrations. Shortcomings in Se studies have been identified, and the future research directions of Se in South Africa have been discussed.

Quantitative mapping of mercury and selenium in mushroom fruit bodies with laser ablation-inductively coupled plasma-mass spectrometry

This work describes the development of a novel method for quantitative mapping of Hg and Se in mushroom fruit body tissues with laser ablation coupled to inductively coupled plasma-mass spectrometry (LA-ICP-MS). Different parameters of the protocol for preparation of the standards used for quantification via external calibration were assessed, e.g., the dissolution temperature of gelatin standards and the addition of chitosan and L-cysteine as additives to the gelatin-based calibration droplets to better match the sample matrix. While chitosan was not suited for this purpose, the presence of L-cysteine considerably improved the figures of merit of the calibration, leading to limits of detection of 0.006 and 0.3 µg g-1 for Hg and Se, respectively, at a pixel size of 20 × 20 µm. Further, an in-house reference material, ideally suited for the validation of the method for application to mushroom samples, was successfully prepared from a paste of Boletus edulis. The newly developed method was used to investigate the distribution of Hg and Se in tissue sections of five porcini mushroom individuals of three different species (Boletus edulis, Boletus aereus, and Boletus pinophilus) and one sample of a parasol mushroom (Macrolepiota procera). For one sample, additional areas were ablated at higher spatial resolution, with a laser spot size down to 5 µm, which allows a detailed investigation of the spatial distribution of Hg and Se in mushrooms.

Preconcentration and speciation analysis of mercury: 3D printed metal scavenger-based solid-phase extraction followed by analysis with inductively coupled plasma mass spectrometry

A selective method for preconcentration and determination of methylmercury (MeHg) and inorganic mercury (iHg) in natural water samples at the ng L^-1 level has been developed. The method involves adsorption of Hg species into a 3D printed metal scavenger and sequential elution with acidic thiourea solutions before ICP-MS determination. Experimental parameters affecting the preconcentration of MeHg and iHg such as the sample matrix, effect of the flow rate on adsorption, eluent composition, and elution mode have been studied in detail. The obtained method detection limits, considering the preconcentration factors of 42 and 93, were found to be 0.05 ng L^-1 and 0.08 ng L^-1 for MeHg and iHg, respectively. The accuracy of the method was assessed with a certified groundwater reference material ERM-CA615 (certified total iHg concentration 37 ± 4 ng L^-1). The determined MeHg concentration was below MDL while iHg concentration was determined to be 41.2 ± 0.5 ng L^-1. Both MeHg and iHg were also spiked to natural water samples at 5 ng L^-1 concentration and favorable spiking recoveries of 88-97% were obtained. The speciation procedure was successfully applied to two lake water samples where MeHg and iHg concentrations ranged from 0.18 to 0.24 ng L^-1 and 0.50-0.62 ng L^-1, respectively. The results obtained demonstrate that the developed 3D printed metal scavenger-based method for preconcentration and speciation of Hg is simple and sensitive for the determination of Hg species at an ultra-trace level in water samples.

Analytical Methodologies for Agrometallomics: A Critical Review

Agrometallomics, as an independent interdiscipline, is first defined and described in this review. Metallic elements widely exist in agricultural plants, animals and edible fungi, seed, fertilizer, pesticide, feedstuff, as well as the agricultural environment and ecology, and even functional and pathogenic microorganisms. So, the agrometallome plays a vital role in molecular and organismic mechanisms like environmetallomics, metabolomics, proteomics, lipidomics, glycomics, immunomics, genomics, etc. To further reveal the inner and mutual mechanism of the agrometallome, comprehensive and systematic methodologies for the analysis of beneficial and toxic metals are indispensable to investigate elemental existence, concentration, distribution, speciation, and forms in agricultural lives and media. Based on agrometallomics, this review summarizes and discusses the advanced technical progress and future perspectives of metallic analytical approaches, which are categorized into ultrasensitive and high-throughput analysis, elemental speciation and state analysis, and spatial- and microanalysis. Furthermore, the progress of agrometallomic innovativeness greatly depends on the innovative development of modern metallic analysis approaches including, but not limited to, high sensitivity, elemental coverage, and anti-interference; high-resolution isotopic analysis; solid sampling and nondestructive analysis; metal chemical species and metal forms, associated molecular clusters, and macromolecular complexes analysis; and metal-related particles or metal within the microsize and even single cell or subcellular analysis.

Tin and mercury and their speciation (organotin compounds and methylmercury) in worldwide red wine samples determined by ICP-MS and GC-ICP-MS

One hundred and twenty-two red wines were analysed for their total tin, total mercury and speciation concentrations. Total Sn and Hg concentrations were in average 4.4 ± 7.2 µg/L and 0.22 ± 0.12 µg/L, respectively. Two GC-ICP-MS methods were developed and validated for speciation purposes: one to measure organotin compounds (OTCs) with internal standard correction; the other, to evaluate methylmercury (MeHg⁺) by isotopic dilution. Methyltins (mainly dimethyltin, but also monomethyltin) were the most abundant OTCs recovered. Methylation seems to occur biotically during the wine making process and not during the bottling time. Therefore, it also seems to be roughly dependent on the geographical origin of the wine. For higher OTCs, monobutyltin was the most regularly found, but dibutyltin and monooctyltin were also detected sometimes. MeHg⁺ was not recovered in any of the samples investigated, probably due to the low level of Hg. These results suggest that, in terms of these parameters, normal consumption of wine is not a hazard for human health.

Chemical Speciation of Aluminum in Wine by LC-ICP-MS

Aluminum is very common in the natural environment and in everyday human life. We are living in the "aluminum age." Its average daily intake should not exceed a few mg/day. Unfortunately, despite the growing number of alarming data about the toxicity of this element, human exposure to aluminum is constantly increasing. The toxicity and bioavailability of aluminum depends mainly on the form in which it occurs. The main variables conditioning the form are the concentration, the type, the molar ratio of aluminum to ligand, the pH value, and the temperature. This research presents a new method for speciation analysis of both inorganic and organic aluminum complexes in model solutions by LC-ICP-MS. Different solutions with variable pH values and different Al/ligand molar ratios (fluorides and several organic ligands, e.g., citrates and oxalates ions) were used. The chromatographic separation process was carried out based on isocratic and gradient elution, using a cation exchange analytical column. All determinations have been confirmed based on chemical equilibrium modeling programs. The new developed method was successfully applied for the first time in speciation analysis of real samples: white and red wine.

Rapid extraction of arsenic species from traditional Chinese herbal by dual-frequency ultrasound-assisted enzymatic digestion prior to spectral analysis

Considering the huge difference of biological toxicity, it is extremely significant to recognize the exact content of arsenic species in actual samples. In this paper, a novel pretreatment technique for the efficient extraction of arsenic species from herbal samples is developed by dual-frequency ultrasound-assisted enzymatic digestion (DUED). The preservation of arsenic original form, reduction of the actual analysis time, environmental friendliness and free-interference in subsequent detection make this method over the traditional method such as wet digestion, ashing and some solvent extraction technologies. The combination of DUED and atomic fluorescence spectrometry realize the speciation analysis of arsenic in traditional Chinese medicine. The optimizations of experimental parameters have been achieved, and the potential mechanism is discussed. The experimental data showed that cellulase is suitable for the digestion of herbal matrix than α-amylase and papain. Ultrasound can significantly increase the rate of enzymatic hydrolysis of biological molecules, especially under dual-frequency ultrasound irradiation. The highest relative extraction efficiency can be obtained by combining 40 kHz ultrasonic bath (UB) with 20 kHz ultrasonic probe (UP). Two certified reference materials [CRMs, GBW(E)090066 and GBW(E)090067] and four practical herbs were used to evaluate the accuracy and practicability of the method. Inorganic arsenic, including trivalent arsenic and pentavalent arsenic, was the main species in the four herbal samples.

Biosensors in Monitoring Water Quality and Safety: An Example of a Miniaturizable Whole-Cell Based Sensor for Hg2+ Optical Detection in Water

Inorganic mercury (Hg2+) pollution of water reserves, especially drinking water, is an important issue in the environmental and public health field. Mercury is reported to be one of the most dangerous elements in nature since its accumulation and ingestion can lead to a series of permanent human diseases, affecting the kidneys and central nervous system. All the conventional approaches for assaying Hg2+ have some limitations in terms of bulky instruments and the cost and time required for the analysis. Here, we describe a miniaturizable and high-throughput bioluminescence sensor for Hg2+ detection in water, which combines the specificity of a living bacterial Hg2+ reporter cell, used as sensing element, with the performance of a silicon photomultiplier, used as optical detector. The proposed system paves the basis for portable analysis and low reactants consumption. The aim of the work is to propose a sensing strategy for total inorganic mercury evaluation in water. The proposed system can lay the basis for further studies and validations in order to develop rapid and portable technology that can be used in situ providing remote monitoring.

Applications of Plasma-Liquid Systems: A Review

Plasma-liquid systems have attracted increasing attention in recent years, owing to their high potential in material processing and nanoscience, environmental remediation, sterilization, biomedicine, and food applications. Due to the multidisciplinary character of this scientific field and due to its broad range of established and promising applications, an updated overview is required, addressing the various applications of plasma-liquid systems till now. In the present review, after a brief historical introduction on this important research field, the authors aimed to bring together a wide range of applications of plasma-liquid systems, including nanomaterial processing, water analytical chemistry, water purification, plasma sterilization, plasma medicine, food preservation and agricultural processing, power transformers for high voltage switching, and polymer solution treatment. Although the general understanding of plasma-liquid interactions and their applications has grown significantly in recent decades, it is aimed here to give an updated overview on the possible applications of plasma-liquid systems. This review can be used as a guide for researchers from different fields to gain insight in the history and state-of-the-art of plasma-liquid interactions and to obtain an overview on the acquired knowledge in this field up to now.

Speciation Analysis of Trace Arsenic, Mercury, Selenium and Antimony in Environmental and Biological Samples Based on Hyphenated Techniques

In order to obtain a well understanding of the toxicity and ecological effects of trace elements in the environment, it is necessary to determine not only the total amount, but also their existing species. Speciation analysis has become increasingly important in making risk assessments of toxic elements since the toxicity and bioavailability strongly depend on their chemical forms. Effective separation of different species in combination with highly sensitive detectors to quantify these particular species is indispensable to meet this requirement. In this paper, we present the recent progresses on the speciation analysis of trace arsenic, mercury, selenium and antimony in environmental and biological samples with an emphasis on the separation and detection techniques, especially the recent applications of high performance liquid chromatography (HPLC) hyphenated to atomic spectrometry or mass spectrometry.

In-situ measurement of labile Cr(III) and Cr(VI) in water using diffusive gradients in thin-films (DGT)

The toxicity and bioavailability of Cr depends on its speciation in the aquatic environment. Here, we developed a new method for simultaneously obtaining in-situ data on labile Cr(III) and Cr(VI) using diffusive gradients in thin films (DGT) and high-performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A Zr-oxide DGT was applied to accumulate both labile Cr(III) and Cr(VI). The elution of Cr species was carried out with 50 mM EDTA-2Na at pH 9.5 for 1.5 h. Agilent Bio WAX anion-exchange chromatography was used to separate Cr species in the slightly alkaline mobile phase containing 40 mM NH₄NO₃ at pH 7.4. An ICP-MS was used to quantitatively measure Cr within 4.5 min. Method detection limits were 0.05 μg/L for Cr(III) and 0.02 μg/L for Cr(VI). Labile Cr(III) and Cr(VI) was accurately quantified in synthetic solutions for pH in the range of 5-8 and ionic strength ranging from 10 to 100 mmol L^-1. The method allows quantification of labile Cr(III) and Cr(VI) in natural water and was consistent with results of when a separate measurement method based on DGT was used. This study was an attempt at simultaneous in-situ quantification of labile Cr(III) and Cr(VI), and will facilitate in-situ labile Cr speciation analysis in the environment.

Addressing the practicalities of anodic stripping voltammetry for heavy metal detection: a tutorial review

We highlight the fundamentals and challenges involved with anodic stripping voltammetry (ASV) using solid electrodes providing a practical guide to anyone wishing to undertake analytical ASV.

Analysis of Hazardous Elements in Children Toys: Multi-Elemental Determination by Chromatography and Spectrometry Methods

This paper presents the results of determination of hazardous metal (Cd, Cu, Cr, Hg, Mn, Ni, Pb, Zn) and metalloid (As, Sb) levels in toys available in the Polish market. Two independent sample preparation methods were used to determine the concentration and content of the metals and metalloids. The first one is defined by the guidelines of the EN-71 standard and undertook extraction in 0.07 mol/L HCl. This method was used to conduct speciation analysis of Cr(III) and Cr(VI), as well as for the determination of selected metals and metalloids. The second method conducted mineralization in a HNO₃ and H₂O₂ mixture using microwave energy to determine the content of metals and metalloids. Determination of chromium forms was made using the high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method, while those of metals and metalloids were made using the ICP-MS technique. Additionally, in order to determine total content of chromium in toys, an energy dispersive X-ray fluorescence spectrometer (EDX) was used. The results of the analyses showed that Cr(VI) was not detected in the toys. In general, the content of heavy metals and metalloids in the studied samples was below the migration limit set by the norm EN-71.

Thiolated arsenic in natural systems: What is current, what is new and what needs to be known

Thiolated arsenic compounds are the sulfur analogous substructures of oxo-arsenicals as the arsinoyl (As = O) is substituted by an arsinothioyl (As = S) group. Relatively brief history of thioarsenic research, mostly in the current decade has endeavored to understand their consequences in the natural environment. However, thioarsenic related aspects have by far not attached much research concern on global scale compared to other arsenic species. This review attempts to provide a critical overview for the first time on formation mechanisms of thioarsenicals, their chemistry, speciation and analytical methodologies in order to provide a rational assessment of what is new, what is current, what needs to be known or what should be done in future research. Thioarsenic compounds play a vital role in determining the biogeochemistry of arsenic in sulfidic environments under reducing conditions. Thioarsenic species are widely immobilized by naturally occurring processes such as the adsorption on iron (oxyhydr)oxides and precipitation on iron sulfide minerals. Accurate measurement of thioarsenic species is a challenging task due to their instability upon pH, temperature, redox potential, and concentrations of oxygen, sulfur and iron. Assessment of direct and indirect effects of toxic thioarsenic species on global population those who frequently get exposed to high levels of arsenic is an urgent necessity. Dimethylmonothioarsinic acid (DMMTA^V) is the most cytotoxic arsenic metabolite having similar toxicological effects as dimethylarsinous acid (DMA^III) in human and animal tissues. The formation and chemical analysis of thioarsenicals in soil and sediments are highly unknown. Therefore, future research needs to be more inclined towards in determining the molecular structure of unknown thioarsenic complexes in various environmental suites. Contemporary approaches hyphenated to existing technologies would pave the way to overcome critical challenges of thioarsenic speciation such as standards synthesis, structural determination, quantification and sample preservation in future research.

Determination of Arsenic Species in Ophiocordyceps sinensis from Major Habitats in China by HPLC-ICP-MS and the Edible Hazard Assessment

This study sought to determine the concentration and distribution of arsenic (As) species in Ophiocordyceps sinensis (O. sinensis), and to assess its edible hazard for long term consumption. The total arsenic concentrations, measured through inductively coupled plasma mass spectrometry (ICP-MS), ranged from 4.00 mg/kg to 5.25 mg/kg. As determined by HPLC-ICP-MS, the most concerning arsenic species—AsB, MMA^V, DMA^V, As^V, and As^Ш—were either not detected (MMA^V and DMA^V) or were detected as minor As species (AsB: 1.4⁻2.9%; As^V: 1.3⁻3.2%, and As^Ш: 4.1⁻6.0%). The major components were a cluster of unknown organic As (uAs) compounds with As^Ш, which accounted for 91.7⁻94.0% of the As content. Based on the H₂O₂ test and the chromatography behavior, it can be inferred that, the uAs might not be toxic organic As. Estimated daily intake (EDI), hazard quotient (HQ), and cancer risk (CR) caused by the total As content; the sum of inorganic As (iAs) and uAs, namely i+uAs; and iAs exposure from long term O. sinensis consumption were calculated and evaluated through equations from the US Environmental Protection Agency and the uncertainties were analyzed by Monte-Carlo Simulation (MCS). EDI_{total As} and EDI_i+uAs are approximately ten times more than EDI_iAs; HQ_totalAs and HQ_i+uAs > 1 while HQ_iAs < 1; and CR_{total As} and CR_i+uAs > 1 × 10⁻⁴ while CR_iAs < 1 × 10⁻⁴. Thus, if the uAs is non-toxic, there is no particular risk to local consumers and the carcinogenic risk is acceptable for consumption of O. sinensis because the concentration of toxic iAs is very low.

Inorganic Arsenic Determination in Food: A Review of Analytical Proposals and Quality Assessment Over the Last Six Years

Here we review recent developments in analytical proposals for the assessment of inorganic arsenic (iAs) content in food products. Interest in the determination of iAs in products for human consumption such as food commodities, wine, and seaweed among others is fueled by the wide recognition of its toxic effects on humans, even at low concentrations. Currently, the need for robust and reliable analytical methods is recognized by various international safety and health agencies, and by organizations in charge of establishing acceptable tolerance levels of iAs in food. This review summarizes the state of the art of analytical methods while highlighting tools for the assessment of quality assessment of the results, such as the production and evaluation of certified reference materials (CRMs) and the availability of specific proficiency testing (PT) programmes. Because the number of studies dedicated to the subject of this review has increased considerably over recent years, the sources consulted and cited here are limited to those from 2010 to the end of 2015.

Comparison of Three Analytical Methods for the Quantitation of Mercury in Environmental Samples from the Volta Lake, Ghana

Three analytical methods using automatic mercury analyzer (AMA), direct mercury analyzer (DMA) and inductively coupled plasma-mass spectrometry (ICP-MS) were applied to determine mercury in fish and sediment samples from the Volta Lake in Ghana with the aim of comparing their accuracy, precision, and limit of quantifications. There was statistically no significant difference (p < 0.05) between the concentrations recorded by the methods. This indicates their suitability for the accurate determination of mercury. Limit of quantification was found to be in the order; ICP-MS (0.053 ng/g) < DMA (0.527 ng/g) < AMA (2.193 ng/g). Though each of the three methods has a suitable ability in determining accurately the concentrations of mercury in fish and sediment, for the determination of very low concentrations of mercury ICP-MS should be preferred considering the order of the detection limit which follows the trend ICP-MS (0.016 ng/g) < DMA (0.158 ng/g) < AMA (0.509 ng/g).

Mass spectrometric detection of trace anions: The evolution of paired-ion electrospray ionization (PIESI)

The negative-ion mode of electrospray ionization mass spectrometry (ESI-MS) is intrinsically less sensitive than the positive-ion mode. The detection and quantitation of anions can be performed in positive-ion mode by forming specific ion-pairs during the electrospray process. The paired-ion electrospray ionization (PIESI) method uses specially synthesized multifunctional cations to form positively charged adducts with the anions to be analyzed. The adducts are detected in the positive-ion mode and at higher m/z ratios to produce excellent signal-to-noise ratios and limits of detection that often are orders of magnitude better than those obtained with native anions in the negative-ion mode. This review briefly summarizes the different analytical approaches to detect and separate anions. It focuses on the recently introduced PIESI method to present the most effective dicationic, tricationic, and tetracationic reagents for the detection of singly and multiply charged anions and some zwitterions. The mechanism by which specific structural molecular architectures can have profound effects on signal intensities is also addressed.

Occurrence and removal of butyltin compounds in a waste stabilisation pond of a domestic waste water treatment plant of a rural French town

The aim of this study was to investigate the fate and behaviour of butyltin pollutants, including monobutyltin (MBT), dibutylin (DBT), and tributyltin (TBT), in waste stabilisation ponds (WSP). The study was conducted as part of a baseline survey and included five sampling campaigns comprising bottom sludge and the water column from each pond from a typical WSP in France. Butyltins were detected in all raw wastewater and effluents, reflecting their widespread use. Our results revealed high affinity between butyltins and particulate matter and high accumulation of butyltins in the sludge taken from anaerobic ponds. The dissolved butyltins in the influent ranged from 21.5 to 28.1 ng(Sn).L(-1) and in the effluent, from 8.8 to 29.3 ng(Sn).L(-1). The butyltin concentrations in the sludge ranged from 45.1 to 164 and 3.6-8.1 ng(Sn).g(-1) respectively in the first and last ponds. Our results showed an average treatment efficiency of 71% for MBT, 47% for DBT, 55% for TBT. Laboratory sorption experiments enabled the calculation of a distribution coefficient (Kd = 75,000 L.kg-1) between TBT and particulate matter from the WSPs. The Kd explained the accumulation and persistence of the TBT in the sludge after settling of particulate matter. The continuous supply of contaminated raw wastewater and the sorption-desorption processes in the ponds led to incomplete bio- and photolytic degradation and to the persistence of butyltins in dissolved and particulate matrices throughout the survey period. It is thus recommended to use shallow ponds and to pay particular attention when sludge is used for soil amendment.

Recent Developments in the Speciation and Determination of Mercury Using Various Analytical Techniques

This paper reviews the speciation and determination of mercury by various analytical techniques such as atomic absorption spectrometry, voltammetry, inductively coupled plasma techniques, spectrophotometry, spectrofluorometry, high performance liquid chromatography, and gas chromatography. Approximately 126 research papers on the speciation and determination of mercury by various analytical techniques published in international journals since 2013 are reviewed.

Arsenic, Antimony, Chromium, and Thallium Speciation in Water and Sediment Samples with the LC-ICP-MS Technique

Chemical speciation is a very important subject in the environmental protection, toxicology, and chemical analytics due to the fact that toxicity, availability, and reactivity of trace elements depend on the chemical forms in which these elements occur. Research on low analyte levels, particularly in complex matrix samples, requires more and more advanced and sophisticated analytical methods and techniques. The latest trends in this field concern the so-called hyphenated techniques. Arsenic, antimony, chromium, and (underestimated) thallium attract the closest attention of toxicologists and analysts. The properties of those elements depend on the oxidation state in which they occur. The aim of the following paper is to answer the question why the speciation analytics is so important. The paper also provides numerous examples of the hyphenated technique usage (e.g., the LC-ICP-MS application in the speciation analysis of chromium, antimony, arsenic, or thallium in water and bottom sediment samples). An important issue addressed is the preparation of environmental samples for speciation analysis.

Speciation and determination of bioavailable arsenic species in soil samples by one-step solvent extraction and high-performance liquid chromatography with inductively coupled plasma mass spectrometry

A new analytical method was developed to determine the bioavailable arsenic species (arsenite, arsenate, monomethylarsonic acid, and dimethylarsonic acid) in soil samples using high-performance liquid chromatography with inductively coupled plasma mass spectrometry. Bioavailable arsenic was extracted with ammonium phosphate buffer by a simplified one-step solvent extraction procedure. To estimate the effect of variables on arsenic extraction, a two-level Plackett-Burman factorial design was conducted to screen the significant factors that were further investigated by a separate univariate approach. The optimum conditions were confirmed by compromising the stability of arsenic species and the extraction efficiency. The concentration of arsenic species was determined in method blank and soil-certified reference materials both spiked with standard solutions of arsenic species. All the target arsenic species were stable during the whole extraction procedure. Furthermore, the proposed method was applied to release bioavailable arsenic from contaminated soil samples, showing that the major arsenic species in soil samples were inorganic arsenic: arsenite and arsenate, of which the latter was dominant.

ChelomEx: Isotope-assisted discovery of metal chelates in complex media using high-resolution LC-MS

Chelating agents can control the speciation and reactivity of trace metals in biological, environmental, and laboratory-derived media. A large number of trace metals (including Fe, Cu, Zn, Hg, and others) show characteristic isotopic fingerprints that can be exploited for the discovery of known and unknown organic metal complexes and related chelating ligands in very complex sample matrices using high-resolution liquid chromatography mass spectrometry (LC-MS). However, there is currently no free open-source software available for this purpose. We present a novel software tool, ChelomEx, which identifies isotope pattern-matched chromatographic features associated with metal complexes along with free ligands and other related adducts in high-resolution LC-MS data. High sensitivity and exclusion of false positives are achieved by evaluation of the chromatographic coherence of the isotope pattern within chromatographic features, which we demonstrate through the analysis of bacterial culture media. A built-in graphical user interface and compound library aid in identification and efficient evaluation of results. ChelomEx is implemented in MatLab. The source code, binaries for MS Windows and MAC OS X as well as test LC-MS data are available for download at SourceForge ( http://sourceforge.net/projects/chelomex ).

Chromium and its speciation in water samples by HPLC/ICP-MS--technique establishing metrological traceability: a review since 2000

Chromium holds a special position among living organisms because depending on its species it can be either essential or toxic. Cr(VI) even at very low concentrations is harmful and carcinogenic, while Cr(III) is a necessary microelement for cellular metabolism. Therefore, a simple analysis of Cr concentration in collected samples will not be able to distinguish these differences effectively: for a proper chemical analysis we need to perform a reliable detection and quantification of Cr species. Separation and detection of chromium can be accomplished with high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-MS) in a one-step. Our review assembles articles published since 2000 regarding chromium speciation in water samples with the use of HPLC/ICP-MS. It addresses the following issues: chromium chemistry, the possibilities of dealing with interferences, metrological aspects, analytical performance and speciated isotope dilution mass spectrometry (SIDMS) which is a definitive measurement method. The authors would like to advocate this hyphenated advanced technique as well as the metrological approach in speciation analysis of chromium.

Analysis of gold(I/III)-complexes by HPLC-ICP-MS demonstrates gold(III) stability in surface waters

Understanding the form in which gold is transported in surface- and groundwaters underpins our understanding of gold dispersion and (bio)geochemical cycling. Yet, to date, there are no direct techniques capable of identifying the oxidation state and complexation of gold in natural waters. We present a reversed phase ion-pairing HPLC-ICP-MS method for the separation and determination of aqueous gold(III)-chloro-hydroxyl, gold(III)-bromo-hydroxyl, gold(I)-thiosulfate, and gold(I)-cyanide complexes. Detection limits for the gold species range from 0.05 to 0.30 μg L(-1). The [Au(CN)2](-) gold cyanide complex was detected in five of six waters from tailings and adjacent monitoring bores of working gold mines. Contrary to thermodynamic predictions, evidence was obtained for the existence of Au(III)-complexes in circumneutral, hypersaline waters of a natural lake overlying a gold deposit in Western Australia. This first direct evidence for the existence and stability of Au(III)-complexes in natural surface waters suggests that Au(III)-complexes may be important for the transport and biogeochemical cycling of gold in surface environments. Overall, these results show that near-μg L(-1) enrichments of Au in environmental waters result from metastable ligands (e.g., CN(-)) as well as kinetically controlled redox processes leading to the stability of highly soluble Au(III)-complexes.