The use of atomic fluorescence spectrometry (AFS) coupled to gas and liquid chromatography has been used for mercury speciation measurements for a number of years. The major routes of human exposure to mercury is via inhalation of mercury vapour as Hg0 from sources such as dental amalgams and occupational exposure, consumption of fish products as CH3Hg+ and also from vaccines which contain the Thiomersal preservative CH3CH2Hg+ (known in the US as Thimerosal).

Different mercury species have varying toxicological effects and also different routes of detoxification. Total mercury in hair for a non exposed person is typically in the range of 0.4 to 6.0mg/g which is several 100 times higher than the level typically found in blood. It has been reported[1] that the mercury in first cut baby hair from children with Autism is significantly lower suggesting that they have an inability to excrete mercury from their system. The excretion mechanism is not fully understood at this time and therefore there is a need for reliable methods to determine Hg speciation in hair samples.

This paper will compare different analytical extraction methods and their suitability for liquid and gas chromatography coupled to AFS. Data will be presented for a wide range of hair samples and comparisons made for different exposure groups.

[1] Holmes A S, Blaxill, M F & Haley B E, Int. J. Toxicol. 2003, 22 (4) 277

Online Process Analysis of Mercury in Petrochemical Streams

Knowledge of the mercury content in petrochemicals is extremely important. Firstly, mercury is highly toxic and is of environmental concern and secondly, the damage caused to petrochemical plants can be financially crippling especially when unscheduled shutdowns are forced. Mercury has been found to be responsible for many cases of selective hydrogenation catalyst deactivation. Palladium based catalysts are commonly used for the selective hydrogenation of alkynes in the steam cracking of C2 to C4 cuts. Mercury is known to be the cause of corrosion problems with alumina-based heat exchangers, rotors and condensers at natural gas refinery plants. Heat exchanger replacement is a costly operation due to the capital investment of the exchanger itself and the plant down time incurred for its replacement. This paper describes how atomic fluorescence spectrometry (AFS) can be applied to the measurement of mercury in petrochemical samples such as natural gas, LPG, LNG, naphtha and condensates. Typically these measurements are performed using offline laboratory techniques which are highly dependent on the sampling protocols utilized and the sample storage method. This is especially problematic for volatile forms of Hg which are easily lost from the sample. We have recently developed online process analyzers for both liquid and gaseous petrochemical streams. These are typically used in conjunction with mercury removal technologies so that the efficiency can be monitored in real time thus protecting expensive downstream apparatus. The performance characteristics of the analyzers will be discussed with reference to sampling, calibration, accuracy, precision and long term reliability.

The origins of the ‘Dumarey equation’ describing the saturated mass concentration of mercury vapour in air

Mercury has been recognised as an environmental air pollutant for many years. Usually analyses are carried out by cold vapour amalgamation coupled to atomic spectrometry techniques with a calibration based on injection of air saturated with mercury vapour. All these measurements are ultimately traceable to the saturated mass concentration of mercury in air at a given temperature, as this relationship underpins the calibration procedure.

The saturated mass concentration of mercury vapour in air is given indirectly via the ideal gas law by a variety of empirical equations describing the vapour pressure of mercury. Recent work to develop a standardized European method for the measurement of mercury vapour in air has brought into sharp focus the requirement to define the most suitable relationship for the saturated mass concentration of mercury in air.

The ‘Dumarey equation’ has been the dominant relationship used to calculate the saturated mass concentration of mercury vapour in air for over 25 years. However, the origin of the equation and the validation data supporting its accuracy has never been published. We now address that deficiency and compare the Dumarey equation with other data sets to which it has been wrongly attributed in the past, and describe why it remains superior to the use of mercury vapour pressure data in combination with the ideal gas law.

[1] Huber, M L, Laesecke A, Friend D G, Ing. Eng. Chem. Res. 2006, 45, 7351

Rapid Arsenic Speciation Analysis in Water Samples

Inorganic arsenic (arsenite and arsenate) are the most common arsenic species found in water samples. They are proven to be carcinogenic due to their much higher toxicity than organic arsenic forms. Fast and accurate screening of inorganic arsenic species in water samples has increasingly received great attention. Arsenic generally presents in water samples at low ng/ml levels, and the transformation between arsenite and arsenate can also be troublesome during the sample collection and transportation processes. In this presentation, a fast, easy yet accurate sampling method and sensitive analysis protocol is proposed for arsenic speciation in water samples.

Two cartridges (A and B) were used to collect water samples for arsenic speciation. An aliquot of the water sample (100 ml) was passed through cartridge A or B. Cartridge A is packed with a modified C8 absorbent which only retains arsenite, and cartridge B is packed with anion exchange material which only retains arsenate. Samples were collected on these cartridges on site and subsequently shipped to the lab. Cartridges not only pre-concentrate arsenic in the water samples, but also avoid the inter-specie transformation. Upon receipt of the sample in the lab, 10 ml of 25 % (v/v) HCl was passed through the cartridge and the arsenite or arsenate was eluted. The eluent was then pre-reduced by the addition of 2% KI (m/v) prior to the analysis by hydride generation – atomic fluorescence spectrometry. This procedure greatly reduces the risk of specie transformation, as well as increasing the precision and sensitivity of the analysis.

Developing international standards for sub ppb determination of the hydride forming elements in water samples using AAS and AFS

This paper will focus on the methodology for the hydride generation of As, Sb and Se prior to measurement using AAS and AFS. Data from a series of International ISO Interlaboratory trials undertaken by seventeen laboratories will be presented.

Analytical performance data from the participating laboratories will be critically evaluated and discussed.

The benefits of atomic fluorescence and atomic absorption will be compared.

AAMG Christmas 2008 Meeting: Airborne Particles - Origins, Composition and Effects

Arsenic Speciation in Atmospheric Total Suspended Particles using Atomic Fluorescence Spectrometry

Warren Corns and Peter Stockwell, P S Analytical

V Oliveira, J L Gomez-Ariza and D Sanchez-Rodas, University of Huelva, Spain

Air quality is of great concern to human health. Atmospheric pollution caused by metals in particulate matter has a major impact especially for arsenic because of its high toxicity and carcinogenic properties. Arsenic is released to the atmosphere by the smelting of metals, the combustion of fuels, and the use of pesticides; volcanic activity is the main natural source. Airborne particles are classified according to their size distribution. Physical speciation studies commonly distinguish between total metal concentration in total suspended particles (TSP), or particulate matter with a diameter of specified size, for example 10 or 2.5 μm (PM10 or PM2.5).

Arsenic speciation is of interest because the toxicity varies depending on oxidation state and molecular structure. Inorganic species of arsenic such as arsenite, As(III), and arsenate, As(V) are more toxic that methylated species such a monomethylarsonate (MMA) and dimethlylarsinate (DMA). Inorganic as (III) is more toxic than As(V) not only by ingestion but also by inhalation.

This study summarizes the work to develop quantitative liquid extraction procedures for chemical speciation of arsenic in atmospheric TSP. Different extracting solutions (water, H₃PO₄, and NH₂OH.HCl) were investigated with the aid of microwave or ultrasonic radiation. The optimised extraction procedures were applied to TSP samples collected at the city of Huelva, an industrialized urban site in south-western Spain.

BNASS 2008

25 Years Experience of Vapour Generation Techniques for quantifying Mercury Levels in a Range of Environmental Samples

Peter B Stockwell, Warren Corns and Jasmina Allen

P S Analytical began its life as a designer of vapour generation systems for the measurement of the hydride forming elements and mercury by atomic absorption spectrometry. In 1983 a semi-automated system was developed for commercial atomic absorption spectrometry. However, the full potential of the technique was not fully realised until 1987, when the technique was coupled to atomic fluorescence spectrometry and commercialised. Whilst other measurement techniques are now commonly used for the determination of arsenic, antimony, selenium and mercury, atomic fluorescence spectrometry offers significant advantages when reliable, precise measurements are required. The vapour generation AFS approach can also be coupled to chromatographic techniques to provide speciation profiles for these elements and ensure correct treatment in order to take preventative action on these environmental samples.

Using Millennium Excalibur for the Speciation of Arsenic and Selenium Metabolites in Human Urine

Bin Chen, Jasmina Allen, Warren T Corns and Peter B Stockwell

Urinary As and Se metabolites are used frequently in epidemiological and environmental health studies as a means of assessing exposure to As and Se from various sources. The concentrations of urinary As and Se methylation are often found low enough (~ ng/ml) which require sensitive analytical methods involving speciation, identification and quantification of each individual species. Using Millennium Excalibur system based on high performance liquid chromatography coupled with hydride generation atomic fluorescence spectroscopy (HPLC-HG-AFS), As metabolites such as arsenobetaine, arsenite, dimethylarsenic acid, monomethylarsonic acid and arsenate, and Se metabolites such as selenosugar, selenite, selenate, selenomethionine, selenoethionine have been separated using ion-pairing reverse phase HPLC within 10 and 15 minutes for As and Se, respectively. A mobile phase of pH 9 containing 20mM ammonium phosphate, 5mM TBAH and 4% ethanol was used for As speciation, and a mobile phase of pH 4 containing 30mM Ammonium Formate, 1% methanol, and 0.01mM DDAB. The eluent was further digested using an online post column UV digestion device at 200 °C, followed by the sensitive detection of HGAFS which was able to provide detection limits of 0.4-0.8 ng/ml for all the As and Se species.

Sampling – Still the Achilles Heel for Accurate Mercury Measurements in Petrochemical Samples

Matthew Dexter, Warren T Corns and Peter B Stockwell

As we increase our knowledge of measurement techniques in analytical science, little, if any, effort is being made on the Achilles Heel of analysis – the provision of a truly representative sample. Mercury is of considerable interest in the Petrochemical industry as it causes many failures of processing plants. Atomic fluorescence measurements, combined with well designed sampling strategies provide the Petrochemical industry with three mechanisms to (a) determine the levels of mercury present in the samples (b) the precise distribution of the mercury species and (c) the mechanisms to remove the mercury species and render the sample suitable for continuing use in the industry.

Atomic fluorescence spectrometry provides a viable measurement tool which coupled to tailored sampling systems for both online and offline applications serve the industry well. Experiences operating several systems which range from natural gas to liquefied natural gas condensates will be described. Many of these systems have been operating continuously since 1996.

2nd INTERNATIONAL CONGRESS - ARSENIC IN THE ENVIRONMENT

Determination of Arsenic Species using Liquid Chromatography coupled to Hydride Generation Atomic Fluorescence Spectrometry

Prof Peter Stockwell, Dr Warren Corns, Dr Bin Chen and Jasmina Allen

Arsenic and its compounds are known to cause several adverse health effects including cancers of the skin, bladder, kidney, and lung, and diseases of the blood vessels of the legs and feet. P S Analytical supplies dedicated analysis systems for both total and species determination. Speciation is important to monitor levels of individual Arsenic species as the toxicity of certain elements depends very heavily on their physico-chemical form. Urinary As metabolites are used frequently in epidemiological and environmental health studies as a means of assessing exposure to As from various sources. The concentrations of urinary As methylation are often found to be at low enough levels (~ ng/ml) to require sensitive analytical methods involving speciation, identification and quantification of each individual species. Using Millennium Excalibur system based on high performance liquid chromatography coupled with hydride generation atomic fluorescence spectroscopy (HPLC-HG-AFS), As metabolites such as arsenobetaine, arsenite, dimethylarsenic acid, monomethylarsonic acid and arsenate have been separated using ion-pairing reverse phase HPLC within 10 minutes. A mobile phase of pH 9 containing 20mM ammonium phosphate, 5mM TBAH and 4% ethanol was used for the separation of Arsenic species. The eluent was further digested using an online post column UV digestion device at 200°C, followed by the sensitive detection of HGAFS which was able to provide sub ppb detection limits.

4th INTERNATIONAL CONFERENCE ON TRACE ELEMENT SPECIATION IN BIOMEDICAL, NUTRITIONAL AND ENVIRONMENTAL SCIENCES

Method Development for Selenium Speciation in Selenium Nutritional Supplements and Urine using HPLC UV-HG-AFS

Bin Chen, Tessy A Momoh, Warren T Corns and Peter B Stockwell

A new technique for the speciation of selenocysteine, selenomethionine, selenite, selenate and selenosugar1 was developed using high performance ion-pair reverse phase chromatography coupled with atomic fluorescence spectrometry.

Selenium species were separated using a mobile phase of pH 4 containing 40mM ammonium formate, 0.01mM DDAB, 0.5% (v/v) methanol at 0.8ml min^-1 on a Gemini C18 column (250 x 4.6mm, 5µm) and then digested by online ultra violet (UV) irradiation at elevated temperature. Hydride generation was used as sample introduction technique, and this was maximized for all species by the optimization of variable analytical parameter. The final optimized conditions for UV-HG-AFS were 50% (v/v) HCl + 5% (m/v) KBr as oxidant, 0.8% (m/v) NaBH₄ in 1% (m/v) NaOH as reductant, 250ml min^-1 argon flow rate and 150°C temperature. Selenium nutritional supplements and urine samples were analyzed, and the detection limit obtained was range 0.9ng ml^-1 to 3ng ml^-1. One of the most significant findings of this research was that selenomethionine was found to be metabolized to selenosugar1 and excreted in urine.

APPLICATION OF MASS SPECTROMETRY TO SPECIATION ANALYSIS IN THE LIFE SCIENCES

Method Development For Selenium Speciation in Selenium Supplement Tablets
and Urine - Using HPLC UV-HG-AFS

Tessy Momoh, Dr Warren Corns and Jasmina Allen, P S Analytical

A new technique for the speciation of Selenocysteine, Selenomethionine, Selenite, Selenate and Selenosugar (1) was developed using high performance ion-pair reverse phase chromatography coupled with atomic fluorescence spectrometry.

Selenium species were separated on a phenomenexä Gemini C18 column and then digested by online ultraviolet (UV) irradiation at an elevated temperature which destroyed high molecular organo-seleniums. Hydride generation was used as a sample introduction technique to improve sensitivity for the atomic fluorescence detection.

The hydride generation was maximized for all selenium species by optimizing the argon flow rates and the NaBH4 concentration. The online oxidation and breakdown of seleno-proteins was obtained by the optimization of the heater temperature. The final optimized conditions for UV-HG-AFS were 50% HCl with 5% KBr as oxidant, 0.8% NaBH4 in 1% NaOH as reductant, 250ml min^-1 Argon Flow rate and 150ºC temperature. Final Optimized conditions for HPLC were phenomenexä Gemini 250 x 4.6mm C18, 40mM ammonium formate buffer + 1x10-5 DDAB + 0.5% MeOH as Mobile phase at 0.8ml min^-1 and pH4. The detection limit range was 0.9 to 3ng ml^-1.

Selenious yeast supplement and urine samples were analyzed. One of the most significant findings of this research was that SeMet was found to be metabolized to Selenosugar and excreted in urine.

TraceSpec 2007

Speciation of Five Arsenic Metabolites in Urine Using High Performance Liquid Chromatography and Post Column UV Digestion Coupled with Hydride Generation Atomic Fluorescence Spectrometry (HPLC-UV-HGAFS)

Dr Bin Chen, Warren T Corns, Peter B Stockwell, P S Analytical
Zorimar Rivera-Nunez, Environmental Health Science, School of Public Health, University of Michigan, Ann Arbor, MI, USA

Arsenic and its compounds are known to cause several adverse health effects. Urinary As metabolites were used recently in epidemiological and environmental health studies as a means of assessing exposure to arsenic from drinking water. The concentrations of urinary As methylation are often found low enough (~ ng/ml) which require sensitive analytical methods involving speciation, identification and quantification of each individual As species. Arsenobetaine (AsB), arsenite (AsIII), dimethylarsenic acid (DMAV), monomethylarsonic acid (MMAV) and arsenate (AsV) have been separated in one single chromatogram run using ion-pairing reverse phase HPLC within 10 minutes. A mobile phase of pH 9 containing 20mM ammonium phosphate, 5mM TBAH and 4% ethanol was used. The eluent was further digested using an online post column UV digestion device at 200°C, followed by the sensitive detection of HGAFS which was able to provide detection limits of 0.4-0.8 ng/ml for all the arsenic species. The developed method provided a sensitive, robust approach for the monitoring of arsenic methylations in human urine samples.

Determination of Mercury Species in Portuguese Salt Marshes using Capillary GC - Atomic Fluorsecence Spectrometry

Dr Warren Corns, Prof Peter Stockwell and Dr Derek Bryce, P S Analytical
M Válega and E Pereira, University of Aveiro, Portugal
M Pardal, University of Coimbra, Portugal

Salt marshes located near by industrialised areas can act as natural sinks for trace metals. Anthropogenic metals, associated with suspended particulate matter can be transported by tidal currents and trapped by vegetation with subsequent incorporation into sediments. Plant roots can interact with the surrounding sediment, exuding oxygen and organic compounds that influence the distribution and availability of trace metals; however, the amount of metals taken up by the plants is dependent of the metal availability in the sediment, and this is modified by the root activity. Oxygenation of upper estuarine sediments decreases rapidly with depth due to the consumption of oxygen in the oxidation process of the organic matter; however, salt marsh sediments receive an additional input of oxygen in the sub-surface layers through the well developed aerenchyma of salt marsh plants (halophytes) which transports oxygen from leaves to roots and consequently to the surrounding sediments. This supply of oxygen can alter significantly the redox status of sediments with strong repercussions on the biogeochemistry of nutrients and trace elements, namely mercury. The methylation of mercury in salt marsh sediments is poorly documented, although abundant micro-organisms and strong redox gradients between roots and surrounding sediments may favour that process. Because the sediment environment in salt marshes is exceedingly complicated it is pertinent to investigate the conversion of inorganic mercury into organomercury species. A fully automated GC coupled to atomic fluorescence spectrometer will be described for the determination of methylmercury in sediments and salt marsh plants.

Air Quality VII

SI Traceability of Mercury Calibrations

Dr Warren Corns, Prof Peter Stockwell and Dr Matthew Dexter, PS Analytical Ltd, Arthur House, Unit 3 Crayfields Industrial Estate, Orpington, Kent, BR5 3HP, UK.
Dr Andrew Brown and Dr Richard Brown, Analytical Science Team, National Physical Laboratory, Teddington, Middlesex, TW11 0LW, UK.
Dr Ronny Dumarey, ArcelorMittal Gent, John Kennedylaan 51 | B-9042 Gent, Belgium

The calibration of gas phase mercury monitors depends upon having a reliable calibration standard. Traditionally, the most robust means of calibrating online equipment was the manual injection of mercury-saturated air. The Dumarey equation, a well characterised relationship between temperature and saturated concentration, together with knowledge of the gas temperature and volume injected is used to determine the mass of mercury introduced. The accuracy of this procedure will be critically discussed, including thermodynamic and kinetic considerations and experimental data demonstrating systematic biases. In addition to this, the uncertainty and SI traceability relating to the validity of the Dumarey equation will be presented. This work was conducted due to the recently proposed saturated vapour pressure equation by NIST, which is approximately 7% higher than the Dumarey equation.

The authors have developed a mercury calibration gas generator based on the dilution of Hg saturated vapour at known temperature using certified mass flow controllers. The expanded uncertainty of this device was calculated to be 1.7% when operated in the range of 1 to 10µg/m3. The accuracy of the generator was independently verified using Isotope Dilution CV-ICP-MS and also by gravimetric techniques. The data from these tests strongly support the use of the Dumarey equation as the most appropriate relationship between temperature and Hg saturated vapour concentration. Amongst other applications, this device has been used for the online calibration of workroom air monitoring equipment and natural gas and stack gas analysers, thus minimising operator time required compared to the manual injection technique.

A simple device, based on the dilution of the calibration gas under controlled conditions, has been developed to enable the automatic calibration of air monitoring equipment at the ng/m3 concentration level to be carried out routinely. The accuracy and stability of this approach will be demonstrated for the application of online ambient air measurements.

Expanded Uncertainty Model for the Determination of Total Gaseous Mercury in Ambient Air using Amalgamation coupled to Atomic Fluorescence Spectrometry

Dr Warren Corns and Prof Peter Stockwell, PS Analytical Ltd, Arthur House, Unit 3 Crayfields Industrial Estate, Orpington, Kent, BR5 3HP, UK.
Dr Andrew Brown and Dr Richard Brown, Analytical Science Team, National Physical Laboratory, Teddington, Middlesex, TW11 0LW, UK.

Measurements of mercury in ambient air are assuming greater importance, because of increasing health concerns and legislative requirements. The general public and the environment can be exposed to mercury originating from natural, domestic or industrial processes. Coal-burning power plants are the largest anthropogenic source of mercury emissions to the air. Burning hazardous wastes, the chlor-alkali industry, crematoria, breaking mercury products, and spilling mercury, as well as the improper treatment and disposal of products or wastes containing mercury, can also release it into the environment.

In order to have confidence in measured values and to assess compliance with target values, measurements must be made with validated methodologies which have traceable uncertainty statements associated with them. This paper presents a practical uncertainty budget for the measurement of vapour-phase mercury in ambient air, sampling onto a gold-coated silica adsorption tube and measuring with atomic fluorescence spectrometry. Moreover, this budget may be generalized for other related measurement methods for mercury vapour and other ambient air pollutants. All significant sources of uncertainty will be discussed and estimated. Expanded relative uncertainties at the 95% confidence interval will be estimated for exemplar measurements made by the National Physical Laboratory (NPL) as part of the UK Heavy Metals Monitoring Network. Long term TGM data will be presented representing numerous sites around the UK and Europe in rural, urban and industrial locations. The model has been incorporated into the ISO/CEN draft method 15852 entitled “Standard method for the determination of Total Gaseous Mercury

Arsenic Speciation in Atmospheric PM 2.5 and PM 10 using Hydride Generation - Atomic Fluorescence Spectrometry

Dr Warren Corns, Prof Peter Stockwell, PS Analytical Ltd, Arthur House, Unit 3 Crayfields Industrial Estate, Orpington, Kent, BR5 3HP, UK.
Dr V Oliveira, Dr JL Gomez-Ariza and Dr D Sanchez-Rodas, University of Huelva, Campus Univ, El Carmen, 21071, Huelva, Spain

This study summarizes the work to develop quantitative liquid extraction procedures for chemical speciation of arsenic in atmospheric TSP. Different extracting solutions (water, H3PO4, and NH2OH.HCl) were investigated with the aid of microwave or ultrasonic radiation. The optimised extraction procedures were applied to TSP samples collected at the city of Huelva, an industrialized urban site in south-western Spain.

Pittsburgh Conference 2009

Mercury in Crematoria using Atomic Fluorescence Spectrometry

Warren T Corns, Peter B Stockwell and Matthew A Dexter, P S Analytical

The fate of mercury in the environment continues to cause concerns and legislation in Europe is now focussing attention on the mercury emission levels from crematoria. Several manufacturers of Crematoria are designing abatement systems to control the mercury levels emitted. This is not a simple problem, because the mercury levels are not consistent and can reach higher levels that cause concern. In addition to abatement, the legislation will require measurements and reporting the levels of emission.

The P S Analytical range of atomic fluorescence instruments, particularly the Sir Galahad, provide an ideal facilitator to both act as a control mechanism and to provide reliable measurement data suitable for regulatory purposes. Several abatement technologies are currently being developed and the PSA atomic fluorescence spectrometer provides these with the necessary facilities to evaluate the technologies and to fine tune their performance for this emissions requirement.

Examples of the technologies developed and their interaction with the atomic fluorescence measurements will be described.

Recent Improvements in Atomic Fluorescence Spectrometry for the Speciation of Hydride Forming Elements

Bin Chen, Warren T Corns and Peter B Stockwell, P S Analytical

Speciation of some hydride forming elements (As, Se and Sb etc) is extremely challenging because the concentrations of these elements in various samples are often very low (~ng/ml) requiring sensitive analytical methods involving speciation, identification and quantification of each individual specie. Utilising an optimised Millennium Excalibur system based on high performance liquid chromatography coupled with hydride generation atomic fluorescence spectroscopy (HPLC-HG-AFS), arsenic, selenium and antimony species are able to analysed with excellent sensitivity and stability. The optimised chemical and instrumental conditions allow a wide dynamic range and ultra stable measurement for selenium speciation, e.g. RSDs of signal peak height for eight continuous injection of all four selenium species are between 1-2% (as shown in Fig 1). Detection limits (3s) for these species are between 0.06-0.32 ng ml^-1.

A Practical Uncertainty budget for Ambient Mercury Vapour Measurement

Richard J C Brown, Andrew S Brown and Rachel E Yardley, National Physics Laboratory, Middlesex
Warren T Corns and Peter B Stockwell, P S Analytical

Measurements of mercury in ambient air are assuming greater importance, because of increasing health concerns and legislation in Europe and elsewhere. In order to have confidence in the measured values and to assess compliance with values, measurements must be made using validated methodologies which have traceable uncertainty statements associated with them. A practical uncertainty budget for the measurement of vapour-phase mercury in ambient air, sampling onto a gold-coated silica adsorption tube and measuring with atomic fluorescence spectrometry will be discussed. Moreover, this budget may be generalised for other related measurement methods for mercury vapour and other ambient air pollutants. All significant sources of uncertainty will be discussed and estimated. The expanded relative uncertainties at the 95% confidence interval is approximately 17%. These are estimated for exemplar measurements made by the National Physical Laboratory (NPL) as part of the UK Heavy Metals Monitoring Network.

Automated Online and Offline Determination of Naphtha and Natural Gas Condensates

Warren T Corns, Peter B Stockwell, Matthew A Dexter and Claude A Rogers, P S Analytical

It has long been established that mercury in petrochemical products exist throughout the entire chain of products. Mercury has been responsible for several corrosion induced failures of plants, causing considerable financial losses. Since 1987 P S Analytical has been co-operating with several institutions and commercial companies, including Institut Francais du Petrole and Petronas Malaysia, to apply the P S Analytical Atomic Fluorescence Spectrometry techniques for the measurement of mercury in these products.

Systems to quantify mercury in Natural Gas have been installed for many years using AFS technology and have been operating continuously, these form the basis of ISO 6978:2 and ASTM 6580 procedures. The technology has been further extended to analyse liquefied natural gas and more recently PSA has been able to develop solutions which measure the levels of mercury in naphthas and liquid condensates. The challenges of providing a representative sample and presenting this to the measurement system will be discussed, along with the necessary requirements to extend the range of applications from off-line procedures to fully automated online instrumentation. Examples of both offline and online instrumentation will be shown.

Pittsburgh Conference 2008

Using Millennium Excalibur for the Speciation of Arsenic and Selenium Metabolites in Human Urine

Bin Chen, Tessy A Momoh, Warren T Corns and Peter B Stockwell, P S Analytical,

Arsenic and its compounds are known to cause several adverse health effects. Selenium behaves a dual role in human body both as toxicant and essential trace element at different concentration and the difference of the concentrations are very small. Because urine is a major excretory route for both As and Se, urinary As and Se metabolites were used recently in epidemiological and environmental health studies as a means of assessing exposure to As and Se from various sources. The concentrations of urinary As and Se methylation are often found low enough (~ ng/ml) which require sensitive analytical methods involving speciation, identification and quantification of each individual species. Using Millennium Excalibur system based on high performance liquid chromatography coupled with hydride generation atomic fluorescence spectroscopy (HPLC-HG-AFS), As metabolites such as arsenobetaine, arsenite, dimethylarsenic acid, monomethylarsonic acid and arsenate, and Se metabolites such as selenosugar, selenite, selenate, selenomethionine, selenoethionine have been separated using ion-pairing reverse phase HPLC within 10 and 15 minutes for As and Se, respectively. A mobile phase of pH 9 containing 20mM ammonium phosphate, 5mM TBAH and 4% ethanol was used for As speciation, and a mobile phase of pH 4 containing 30mM Ammonium Formate, 1% methanol, and 0.01mM DDAB. The eluent was further digested using an online post column UV digestion device at 200 °C, followed by the sensitive detection of HGAFS which was able to provide detection limits of 0.4-0.8 ng/ml for all the As and Se species. The developed methods provided sensitive, robust approaches for the monitoring of As and Se methylations in human urine samples.

Determination of Total Gaseous Mercury in Ambient Air using Amalgamation coupled to Atomic Fluorescence Spectrometry

Warren T Corns and Peter B Stockwell, P S Analytical

Richard Brown and Andrew S. Brown, Analytical Science Group, National Physical Laboratory, Teddington, UK

In this paper we will describe automated online instrumentation based on amalgamation with atomic fluorescence spectrometry. A known volume of ambient air at a controlled flow rate is passed over a gold impregnated silica trap. Total Gaseous is pre-concentrated on the gold substrate by amalgamation. After the collection period the Hg is thermally desorbed and subsequently delivered to the atomic fluorescence spectrometer specifically designed to detect Hg. The analytical performance of the system will be presented along with data from rural, coastal and urban industrial sites from several European countries.

Performing EPA Methods 245.7 and 1631 with PSA Millennium Merlin System

Bin Chen, Warren T Corns and Peter B Stockwell, P S Analytical

Mercury is naturally present in aquatic systems in very low concentrations. Due to the long range atmospheric transport and deposition of anthropogenic mercury, elevated concentrations of mercury are found even in remote freshwater system although no direct local contamination sources are present. It is long recognised that mercury is one of the most hazardous toxicant to human and the environment. To protect people and the environment from the mercury, governments and regulatory agencies are introducing ever more stringent guidelines. As a result, analysts are challenged to achieve the ever greater sensitivity. The USEPA approved Method 245.7 and Method 1631 for the determination of low level total mercury in water. Both methods are based on vapor generation atomic fluorescence spectrometry (CV-AFS). In this work, a comparison between performing these two EPA methods with PSA Millennium Merlin system is presented. The methodology, operation procedure, analytical sensitivity, and the quality control criteria are compared in detail.

Field Experience of a Mercury Continuous Emission Monitoring System

Matthew A Dexter, Warren T Corns, Peter B Stockwell.

The Clean Air Mercury Rule provides a regulatory regime for the control of mercury emissions from coal-fired utilities in the United States. The rule requires the installation of continuous emission monitoring systems at the majority of such utilities and provides a detailed regime of tests to validate data from the emissions monitoring system. Elemental and oxidised mercury calibration gases traceable to national standards are required for the validation tests.

The P S Analytical Continuous Emission Monitoring System has been used to monitor gas-phase mercury concentrations in coal-fired utility stack gas. The instrument consists of a sampling probe, heated sample transfer line, sample conditioning system, analyser and calibration modules.

The sampling probe extracts sample from the stack, separates the gaseous sample from fly ash, and delivers the diluted sample to the sample conditioner via the heated sample line. The sample is conditioned to convert all mercury in the sample to elemental mercury and is delivered to the analyser without the need for water injection. Mercury in the sample is determined by amalgamation coupled with atomic fluorescence in the Sir Galahad Analyser, providing a method detection limit of less than 0.01 µg^-3.

A calibration gas generator and delivery manifold system is incorporated to deliver known-concentration calibration gases to the sampling system for system integrity validation tests.

The various components of the PSA Hg CEM will be described and results of recent field experience of the system and compliance with the regulatory tests will be presented.

EUEC 2008

PSA are attending this conference.

EPA 17th Annual Conference

Development of Hg Calibration Systems for Hg CEM Applications

No abstract available please contact PSA for further information.

Air Quality VI: Mercury, Trace Elements...

Development and Testing of an Oxidised Mercury Calibration Gas Source for CEMs and Instrumental Reference Methods

Dr Matthew A Dexter, Dr Isabelle Atheaux, Dr Warren T Corns and Professor PeterB Stockwell, P S Analytical

The Clean Air Mercury Rule has provided the legislation for the regulation and control of mercury emissions from coal fired utilities in the United States. The rule requires periodic testing with elemental mercury and mercury(II) chloride calibration gases to ensure the integrity of the CEMs. These calibration gases are also required by the current draft Instrumental Reference Method. It is therefore essential to develop suitable calibration sources which are traceable to national standards (NIST or other standards bodies) for use in CEM and IRM testing.

Since the introduction of its first mercury continuous emissions monitor P S Analytical has provided a calibration source, the Cavkit, which allows an automatically adjustable set concentration of mercury to be introduced at various stages in the sampling and measurement cycle. This has been successfully used to check calibration and to test the integrity of CEM systems. The system has been evaluated by NIST.

A mercury(II) chloride calibration gas source has been developed for use in CEM and IRM testing. The HgCl₂ generator can be located at the analyser or the sample probe to minimise sample transport issues. Development of the HgCl₂ calibration gas generator and early experiences of this in the field will be described.

Rest of the World

1st Brazilian Meeting on Chemical Speciation - EspeQBrasil-2008

Speciation of Arsenic, Selenium, Antimony and Mercury in Various Samples using HPLC/GC coupling with Vapour Generation Atomic Spectrometry

Bin Chen, Jasmina Allen, Warren T Corns and Peter B Stockwell

The performance of atomic fluorescence spectrometry (AFS) has been improved tremendously over the last four decades since its first application in 1960s. Detection limits of AFS for some elements being reported are among the best of any other analytical methods. AFS particularly offers great sensitivity, selectivity and stability for elemental and speciation analysis for Arsenic, Selenium, Antimony and Mercury. In this presentation, several recent studies using vapour generation AFS are discussed, including: a) the speciation of mercury in hair, soil and petrochemical samples; b) the speciation of antimony in soil samples; c) arsenic and selenium metabolites in human urine samples. Detection limits of total elemental analysis are 0.1-10 ng l^-1 for above mentioned elements. The chemical species being quantified are Hg(II), methylmercury, ethylmercury, antimonite, antimonate, thio-antimonate, arsenite, arsenate, arsenobetaine, DMA, MMA, arsenocholine, TMAO, selenite, selenate, selenosugar^-2, selenocysteine, selenomethionine; their detection limits (3s) range from 0.01 to 0.5 ng ml^-1. The excellent stability of the newly developed instruments will also be demonstrated.

Mercury Speciation in Petrochemical Samples using Cold Vapour Atomic Fluorescence Spectrometry

Warren T Corns, Bin Chen, Luther Rahman and Peter B Stockwell

Petrochemical products are primary feedstock for a variety of industrial processes. Understanding the mercury speciation in these samples is critical for refining operations since the presence of mercury even at low concentrations can have a detrimental effect on numerous refining operations. Removal of mercury from petrochemical products is extremely challenging and the optimization of such processes cannot be achieved without knowledge of the mercury species present in the sample and how they might be transformed on the refinery.

This paper we will describe various methodologies for extracting mercury species in crude oil. Cold vapour atomic fluorescence spectrometry was used as the measurement technique. Particulate mercury was established by filtering through a 0.45 micron filter and digesting/extracting the filter medium. In the particulate mercury fraction we were able to distinguish between mercury sulphide and insoluble mercury. This was carried out using high temperature extractions with aqua regia and dilute nitric acid respectively. In the latter case mercury sulphide was not digested and therefore the mercury sulphide content was obtained by difference. For total dissolved mercury two extractions were investigated. Aqua regia extraction was found to give higher recoveries than heated bromination. Ionic mercury was extracted using a saturated solution of potassium chloride. Organomercury and elemental Hg was determined using a specially designed capillary GC- atomic fluorescence spectrometer after a direct injection of the filtered samples. Results will be presented for a wide range of crude oil from different geographical locations. This procedure is also suitable for mercury speciation in other petrochemical products.

Flow Injection Coupling with Gas Chromatography and Atomic Fluorescence Spectrometry for the Ultra-trace Level Mercury Speciation in Various Environmental and Biological Samples

Warren T Corns, Bin Chen, Jasmina Allen, and Peter B Stockwell

The performance of atomic fluorescence spectrometry (AFS) has been improved tremendously over the last four decades since its first application in 1960s. Detection limits of AFS for mercury species being reported are among the best of any other analytical methods. AFS particularly offers great sensitivity, selectivity and stability for elemental and speciation analysis for Mercury. In this presentation, several recent studies using vapour generation AFS are discussed, including: a) the sample preparation for the speciation of mercury in hair, blood and water samples; b) the online derivatization of inorganic and organic mercury using flow injection with cold vapour AFS systems; c) the online pre-concentration of various mercury species, and followed by d) online separation and detection using GC-AFS system. Detection limits of are in the range of sub pg for mercury species including elemental Hg, methylmercury, dimethylmercury and ethylmercury. The excellent stability and convenience of the newly developed instruments will also be demonstrated.

SI Traceability of calibration techniques for online gas-phase mercury monitors

Warren T Corns, Matthew Dexter and Peter B Stockwell – PSA
Richard Brown and Andrew Brown – NPL
Ronny Dumarey – Arcelor Mittal, Gent, Belgium

The calibration of gas phase mercury monitors depends upon having a reliable calibration standard. Traditionally, the most robust means of calibrating online equipment was the manual injection of mercury-saturated air. The Dumarey equation, a well characterised relationship between temperature and saturated concentration, together with knowledge of the gas temperature and volume injected is used to determine the mass of mercury introduced. The accuracy of this procedure will be critically discussed, including thermodynamic and kinetic considerations and experimental data demonstrating systematic biases. In addition to this, the uncertainty and SI traceability relating to the validity of the Dumarey equation will be presented. This work was conducted due to the newly proposed saturated vapour pressure equation by NIST, which is approximately 7% higher than the Dumarey equation.

The authors have developed a mercury calibration gas generator based on the dilution of Hg saturated vapour at known temperature using certified mass flow controllers. The expanded uncertainty of this device was calculated to be 1.7% when operated in the range of 1 to 10 µg/m3. The accuracy of the generator was independently verified using Isotope Dilution CV-ICP-MS and also by gravimetric techniques. The data from these tests strongly support the use of the Dumarey equation as the most appropriate relationship between temperature and Hg saturated vapour concentration. Amongst other applications, this device has been used for the online calibration of workroom air monitoring equipment and natural gas and stack gas analysers, thus minimising operator time required compared to the manual injection technique.

A simple device, based on the dilution of the calibration gas under controlled conditions, has been developed to enable the automatic calibration of air monitoring equipment at the ng/m³ concentration level to be carried out routinely. The accuracy and stability of this approach will be demonstrated for the application of online ambient air measurements.

The use of atomic fluorescence spectrometry for mercury determination in the petrochemical industry

Warren T Corns and Peter B Stockwell

P S ANALYTICAL "applying the power of atomic fluorescence"

ABSTRACTS

UK

EUROPE

THE AMERICAS

REST OF WORLD

UK

AAMG Christmas 2008 Meeting: Airborne Particles - Origins, Composition and Effects

BNASS 2008

EUROPE

2nd INTERNATIONAL CONGRESS - ARSENIC IN THE ENVIRONMENT

4th INTERNATIONAL CONFERENCE ON TRACE ELEMENT SPECIATION IN BIOMEDICAL, NUTRITIONAL AND ENVIRONMENTAL SCIENCES

APPLICATION OF MASS SPECTROMETRY TO SPECIATION ANALYSIS IN THE LIFE SCIENCES

TRACESPEC 2007

THE AMERICAS

Pittsburgh Conference 2010

Air Quality VII

PITTCON 2009

PITTCON 2008

EPA 17th Annual Conference

Air Quality VI: Mercury, Trace Elements...

REST OF WORLD

ICMGP 2009

9th International Conference on Mercury as a Global Pollutant

1st Brazilian Meeting on Chemical Speciation - EspeQBrasil-2008

ABSTRACTS

Pittcon 2010

Speciation of Mercury in Hair using GC-AFS and HPLC-UV-CV-AFS

Online Process Analysis of Mercury in Petrochemical Streams

The origins of the ‘Dumarey equation’ describing the saturated mass concentration of mercury vapour in air

Rapid Arsenic Speciation Analysis in Water Samples

Developing international standards for sub ppb determination of the hydride forming elements in water samples using AAS and AFS

AAMG Christmas 2008 Meeting: Airborne Particles - Origins, Composition and Effects

Arsenic Speciation in Atmospheric Total Suspended Particles using Atomic Fluorescence Spectrometry

BNASS 2008

25 Years Experience of Vapour Generation Techniques for quantifying Mercury Levels in a Range of Environmental Samples

Using Millennium Excalibur for the Speciation of Arsenic and Selenium Metabolites in Human Urine

Sampling – Still the Achilles Heel for Accurate Mercury Measurements in Petrochemical Samples

2nd INTERNATIONAL CONGRESS - ARSENIC IN THE ENVIRONMENT

Determination of Arsenic Species using Liquid Chromatography coupled to Hydride Generation Atomic Fluorescence Spectrometry

4th INTERNATIONAL CONFERENCE ON TRACE ELEMENT SPECIATION IN BIOMEDICAL, NUTRITIONAL AND ENVIRONMENTAL SCIENCES

Method Development for Selenium Speciation in Selenium Nutritional Supplements and Urine using HPLC UV-HG-AFS

APPLICATION OF MASS SPECTROMETRY TO SPECIATION ANALYSIS IN THE LIFE SCIENCES

Method Development For Selenium Speciation in Selenium Supplement Tablets and Urine - Using HPLC UV-HG-AFS

TraceSpec 2007

Speciation of Five Arsenic Metabolites in Urine Using High Performance Liquid Chromatography and Post Column UV Digestion Coupled with Hydride Generation Atomic Fluorescence Spectrometry (HPLC-UV-HGAFS)

Determination of Mercury Species in Portuguese Salt Marshes using Capillary GC - Atomic Fluorsecence Spectrometry

Air Quality VII

SI Traceability of Mercury Calibrations

Expanded Uncertainty Model for the Determination of Total Gaseous Mercury in Ambient Air using Amalgamation coupled to Atomic Fluorescence Spectrometry

Arsenic Speciation in Atmospheric PM 2.5 and PM 10 using Hydride Generation - Atomic Fluorescence Spectrometry

Pittsburgh Conference 2009

Mercury in Crematoria using Atomic Fluorescence Spectrometry

Recent Improvements in Atomic Fluorescence Spectrometry for the Speciation of Hydride Forming Elements

A Practical Uncertainty budget for Ambient Mercury Vapour Measurement

Automated Online and Offline Determination of Naphtha and Natural Gas Condensates

Pittsburgh Conference 2008

Using Millennium Excalibur for the Speciation of Arsenic and Selenium Metabolites in Human Urine

Determination of Total Gaseous Mercury in Ambient Air using Amalgamation coupled to Atomic Fluorescence Spectrometry

Performing EPA Methods 245.7 and 1631 with PSA Millennium Merlin System

Field Experience of a Mercury Continuous Emission Monitoring System

EUEC 2008

EPA 17th Annual Conference

Development of Hg Calibration Systems for Hg CEM Applications

Air Quality VI: Mercury, Trace Elements...

Development and Testing of an Oxidised Mercury Calibration Gas Source for CEMs and Instrumental Reference Methods

Rest of the World

1st Brazilian Meeting on Chemical Speciation - EspeQBrasil-2008

Speciation of Arsenic, Selenium, Antimony and Mercury in Various Samples using HPLC/GC coupling with Vapour Generation Atomic Spectrometry

Mercury Speciation in Petrochemical Samples using Cold Vapour Atomic Fluorescence Spectrometry

Flow Injection Coupling with Gas Chromatography and Atomic Fluorescence Spectrometry for the Ultra-trace Level Mercury Speciation in Various Environmental and Biological Samples

SI Traceability of calibration techniques for online gas-phase mercury monitors

The use of atomic fluorescence spectrometry for mercury determination in the petrochemical industry

P S ANALYTICAL
"applying the power of atomic fluorescence"

Method Development For Selenium Speciation in Selenium Supplement Tablets
and Urine - Using HPLC UV-HG-AFS