Total and inorganic mercury determination in fish tissue by flow injection cold vapour atomic fluorescence spectrometry

A simple and reliable method for Hg determination in fish samples has been developed. Lyophilised fish tissue samples were extracted in a 25% (w/v) tetramethylammonium hydroxide (TMAH) solution; the extracts were then analysed by FI-CVAFS. This method can be used to determine total and inorganic Hg, using the same FI manifold. For total Hg determination, a 0.1% (w/v) KMnO₄ solution was added to the FI manifold at the sample zone, followed by the addition of a 0.5% (w/v) SnCl₂ solution, whereas inorganic Hg was determined by adding a 0.1% (w/v) L-cysteine solution followed by a 1.0% (w/v) SnCl₂ solution to the FI system. The organic fraction was determined as the difference between total and inorganic Hg. Sample preparation, reagent consumption and parameters that can influence the FI-CVAFS performance were also evaluated. The limit of detection for this method is 3.7 ng g^?1 for total Hg and 4.3 ng g^?1 for inorganic Hg. The relative standard deviation for a 1.0 µg L^?1 CH₃Hg standard solution (n = 20) was 1.1%, and 1.3% for a 1.0 µg L^–1 Hg²⁺ standard solution (n = 20). Accuracy was assessed by the analysis of Certified Reference Material (dogfish: DORM-2, NRCC). Recoveries of 99.1% for total Hg and 93.9% inorganic Hg were obtained. Mercury losses were not observed when sample solutions were re-analysed after a seven day period of storage at 4°C.     

Determination of Mercury and Thallium in Seawater by Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry

Electrothermal vaporization inductively coupled plasma mass spectrometry (ETV‐ICP‐MS) has been applied to the determination of Hg and Tl in seawater samples. Various modifiers were tested for the best signal of these elements. After preliminary studies, 0.3% EDTA, 0.1%m/vTAC and 1% v/v HCl were added to the sample solution to work as the modifier. Since the sensitivities of Hg and Tl in various seawater matrices and aqueous standard solutions were quite different, standard addition method and isotope dilution method were used for the determination of Hg and Tl in these seawater samples. This method was applied to the determination of Hg and Tl in NASS‐4 and CASS‐3 reference seawater samples and seawater samples collected from the Kaohsiung area. Results obtained by isotope dilution method and method of standard additions agreed satisfactorily. Detection limits were in the range of 5‐15 and 0.4‐0.5 ng l^?1 for Hg and Tl in seawater, respectively, with the ETV‐ICP‐MS method. The precision between sample replicates was better than 18%) for all the determinations.     

Messung von Isotopenverhältnissen des Quecksilbers im Breich Seiner Natürlichen Häufigkeit Durch Photonenaktivierungsanalyse

By irradiation of mercury with 15 MeV bremsstrahlung the radionuclides²⁰³Hg,^199mHg and^197mHg were generated. This method is suitable for determination of the isotopic relations¹⁹⁸Hg/²⁰⁴Hg and²⁰⁰Hg/²⁰⁴Hg. From mercury of natural isotopic content and of mercury enriched in²⁰⁴Hg were prepared samples with defined isotopic relations and these irradiated for two hours at the Mikrotron (23–25 μA) of the Joint Institute of Nuclear Research Dubna. The estimated standard deviation of the measured activation relations is approximately 2% (rel.), those of the mass-spectrometric method approximately 1% (rel.)      

Analysis of inorganic mercury species associated with airborne particulate matter/aerosols: method development

This paper describes a method for speciation of Hg associated with airborne particulate matter. This method uses a mini-sampler for sample collection and analysis, thermal desorption for separating Hg species, and inductively coupled plasma mass spectrometry (ICP–MS) for identification and quantification of Hg. Coal fly ash spiked with different Hg compounds (e.g. Hg⁰, HgCl₂, HgO, and HgS) was used for qualitative calibration. A standard reference material with a certified value for Hg concentration was used to evaluate the method. When the temperature of the furnace was programmed at a linear rate of increase of 50° min^–1, different Hg compounds could clearly be separated. Three airborne particulate matter samples were collected in parallel in Toronto, ON, Canada and analyzed using this method. Reproducible results were obtained and Hg⁰, HgCl₂, HgO, and HgS species from these samples were detected.     

High-precision measurement of mercury isotope ratios in sediments using cold-vapor generation multi-collector inductively coupled plasma mass spectrometry

An on-line Hg reduction technique using stannous chloride as the reductant was applied for accurate and precise mercury isotope ratio determinations by multi-collector (MC)-ICP/MS. Special attention has been paid to ensure optimal conditions (such as acquisition time and mercury concentration) allowing precision measurements good enough to be able to significantly detect the anticipated small differences in Hg isotope ratios in nature. Typically, internal precision was better than 0.002% (1 RSE) on all Hg ratios investigated as long as approximately 20 ng of Hg was measured with a 10-min acquisition time. Introducing higher amounts of mercury (50 ng Hg) improved the internal precision to <0.001%. Instrumental mass bias was corrected using ²⁰⁵Tl/²⁰³Tl correction coupled to a standard-sample bracketing approach. The large number of data acquired allowed us to validate the consistency of our measurements over a one-year period. On average, the short-term uncertainty determined by repeated runs of NIST SRM 1641d Hg standard during a single day was <0.006% (1 RSD) for all isotope pairs investigated (²⁰²Hg/¹⁹⁸Hg, ²⁰²Hg/¹⁹⁹Hg, ²⁰²Hg/²⁰⁰Hg, and ²⁰²Hg/²⁰¹Hg). The precision fell to <0.01% if the long-term reproducibility, taken over 11 months (over 100 measurements), was considered. The extent of fractionation has been investigated in a series of sediments subject to various Hg sources from different locations worldwide. The ratio ²⁰²Hg/¹⁹⁸Hg expressed as δ values (per mil deviations relative to NIST SRM 1641d Hg standard solution) displayed differences from +0.74 to −4.00‰. The magnitude of the Hg fractionation per amu was constant within one type of sample and did not exceed 1.00‰. Considering all results (the reproducibility of Hg standard solutions, reference sediment samples, and the examination of natural samples), the analytical error of our δ values for the overall method was within ±0.28‰ (1 SD), which was an order of magnitude lower than the extent of fractionation (4.74‰) observed in sediments. This study confirmed that analytical techniques have reached a level of long-term precision and accuracy that is sufficiently sensitive to detect even small differences in Hg isotope ratios that occur within one type of samples (e.g., between different sediments) and so far have unequivocally shown that Hg isotope ratios in sediments vary within approximately 5‰.     

Differential determination of203Hg and14C or35S in double labelled biological samples

The differential determination of²⁰³Hg and¹⁴C or³⁵S in double labelled biological samples is presented. The biological samples were mineralized with 70% HClO₄ and 30% H₂O₂ in minivals MILLI-6. The γ-activity of²⁰³Hg was measured on a well scintillation counter. The total activity, due to²⁰³Hg and¹⁴C or³⁵S, was measured by the liquid scintillation technique after addition of Aquasol into the same vials. The method of external standard channel ratio was used for standardization. Very good recoveries were obtained: 100±0.7% for²⁰³Hg and 94.6–101.0% for¹⁴C and³⁵S. This method could be used for other β, γ and β-active nuclides with similar β-spectra.     

Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge,As, Cd,Sb, Hg and Bi in cosmetic lotions

A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v l-cysteine, 0.5 μg mL⁻¹ Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng  g⁻¹ for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample.     

Development of pre-concentration procedure for the determination of Hg isotope ratios in seawater samples

Hg concentrations in seawater are usually too low to allow direct (without pre-concentration and removal of salt matrix) measurement of its isotope ratios with multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS). Therefore, a new method for the pre-concentration of Hg from large volumes of seawater was developed. The final method allows for relatively fast (about 2.5 L h⁻¹) and quantitative pre-concentration of Hg from seawater samples with an average Hg recovery of 98 ± 6%. Using this newly developed method we determined Hg isotope ratios in seawater. Reference seawater samples were compared to samples potentially impacted by anthropogenic activity. The results show negative mass dependent fractionation relative to the NIST 3133 Hg standard with δ²⁰²Hg values in the range from −0.50‰ to −1.50‰. In addition, positive mass independent fractionation of ²⁰⁰Hg was observed for samples from reference sites, while impacted sites did not show significant Δ²⁰⁰Hg values. Although the influence of the impacted sediments is limited to the seawater and particulate matter in very close proximity to the sediment, this observation may raise the possibility of using Δ²⁰⁰Hg to distinguish between samples from impacted and reference sites.     

Stripping Voltammetric Determination of Mercury in Fish Oil Capsules Using a Screen‐printed Gold Electrode

This work presents a simple electrochemical method for Hg determination in fish oil capsules using anodic stripping voltammetry (ASV) on a screen‐printed gold electrode (SPGE). Samples were treated in an ultrasonic bath for 15 min in the presence of a 1 : 1 (v/v) concentrated HCl/H₂O₂ mixture at room temperature. The limit of detection (LOD) was estimated as 0.25 μg L⁻¹ (corresponding to 7.6 μg kg⁻¹ of oil) with a linear range between 5 and 400 μg L⁻¹ (90 s of deposition time). The analyzed fish oil samples presented Hg concentration below the LOD value. Recovery values for samples spiked with oil standard containing Hg ranged from 95 to 105 %. The method is precise (inter‐day and intra‐day RSD<4 % for n=3) as well as the SPGE sensors (RSD=4.3 %, n=3), which were used continuously (around 100 analyses without replacement) under such oxidation media. The proposed method is feasible to be applied for on‐site determinations due to the portability of sensing and sample treatment approaches.     

Separation and Removal of Mercury(II) from Water Samples Using (Acetylacetone)‐2‐Thiol‐Phenyleneimine Immobilized on Anion‐Exchange Resin Prior to Determination by Cold Vapor Inductively Coupled Plasma Atomic Emission Spectroscopy

Abstract

(Acetylacetone)‐2‐thiol‐phenyleneimine (H₂L) immobilized on an anion‐exchange resin (Dowex) was used for separation and removal of mercury from natural water samples and for preconcentration prior to its determination by cold vapor inductively coupled plasma atomic emission spectroscopy. The metal was eluted from the column using a solution of 10% thiourea in 0.1 M HCl. The modified resin is higly selective with an exchange capacity of 1.60 mmol g^?1. Various parameters like pH, column flow rate, and desorbing agents are optimized. The proposed method has a linear calibration range of 15–1000 ng/ml Hg(II), with a relative standard deviation at the 15 ng/ml level of 3.5%. The precision of the method (evaluated as the relative standard deviation obtained after analyzing six series of five replicates) was ±4.2% at the 50 ng/ml level of Hg(II). The method has been used for routine determination of trace levels of mercury species in natural waters. The potential application of modified resin for the removal of mercury(II) from two natural water samples (top water and lake water) spiked with 50 ng/ml of mercury (II) was studied by ICP‐AES, and the results proved that excellent percent extraction of mercury(II) from both natural water samples was obtained by column method using modified resin.     

Selective solid-phase extraction of trace mercury(II) using a silica gel modified with diethylenetriamine and thiourea

We describe a solid phase extractor for selective separation and preconcentration of Hg(II) ion. It was prepared by immobilizing the adduct of diethylenetriamine and thiourea on silica gel. The effects of solution acidity, preconcentration time, sample flow rate and volume were optimized. The results show that Hg(II) can be selectively extracted from acidic solutions and in presence of common other metal ions. The adsorbent is stable, can be reused more than 10 times, and the maximum adsorption capacity is 23 mg g^?1. Hg(II) was quantified by inductively coupled plasma optical emission spectrometry. The method has a detection limit of 23 ng L^?1, and the relative standard deviation is <2 %. The procedure was validated by analyzing two standard materials (river sediment and hair powder), and was successfully applied to the preconcentration of Hg(II) in real samples.

Determination of Hg(II) in Environmental Water Samples by Dispersive Liquid Phase Microextraction Combined with Flame Atomic Absorption Spectrometry

In this study, a method of dispersive liquid phase microextraction combined with the flame atomic absorption spectrometry was proposed for the determination of trace Hg using diphenylthiocarbazone as chelating reagent. Several factors which have effect on the microextraction efficiency of Hg, such as pH, extraction and dispersive solvent type and their volume, concentration of the chelating agent, extraction time were investigated, and the optimized experimental conditions were established. After extraction, the enrichment factor was 68. The detection limit of the method was 45 ng mL^?1, and the relative standard deviation for eight determinations of 2 μg mL^?1 Hg was 1.7%. The results for the determination of Hg in environmental water samples (tap water, well water, mineral water and Caspian sea water) have demonstrated the applicability of the proposed method.     

Determination of cadmium,mercury and lead in seawater by electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry

Electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry (ETV-ID-ICP-MS) has been applied to the determination of Cd, Hg and Pb in seawater samples. The isotope ratios of the elements studied in each analytical run were calculated from the peak areas of each isotope. Various modifiers were tested for the best signal of these elements. After preliminary studies, 0.15% m/v TAC and 4% v/v HCl were added to the sample solution to work as the modifier. The ETV-ID-ICP-MS method has been applied to the determination of Cd, Hg and Pb in NASS-4 and CASS-3 reference seawater samples and seawater samples collected from Kaohsiung area. The results for reference sample NASS-4 and CASS-3 agreed satisfactorily with the reference values. Results for other samples determined by isotope dilution and method of standard additions agreed satisfactorily. Detection limits were approximately 0.002, 0.005 and 0.001 ng ml⁻¹ for Cd, Hg and Pb in seawater, respectively, with the ETV-ICP-MS method. Precision between sample replicates was better than 20% for most of the determinations.     

Determination of mercury in urine of Mexican dentists

Mercury levels in the urine of Mexican dentists were determined by instrumental neutron activation analysis. A control group with no suspicion of contamination by mercury was also studied. Acid digestion was used for samples treatment and the presence of ²⁰³Hg was determined by gamma spectroscopy. The ranges of mercury concentration found in urine were: for the dentists group from 0.19 to 11.56 mg Hg/l, with a mean value of 3.16 mg Hg/l and standard deviation of 2.74 mg Hg/l, and for the control group from 0.03 to 0.05 mg Hg/l with a mean value of 0.04 mg Hg/l and standard deviation of 0.01 mg Hg/l. The mercury levels found in urine of dentists are associated with several exposure factors which appear to be positively correlated to its concentration, such as years of dental practice, amalgamation techniques, etc.     

Ultra-trace arsenic and mercury speciation and determination in blood samples by ionic liquid-based dispersive liquid-liquid microextraction combined with flow injection-hydride generation/cold vapor atomic absorption spectroscopy

A simple, fast, and sensitive method for speciation and determination of As (III, V) and Hg (II, R) in human blood samples based on ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) and flow injection hydride generation/cold vapor atomic absorption spectrometry (FI-HG/CV-AAS) has been developed. Tetraethylthiuram disulfide, mixed ionic liquids (hydrophobic and hydrophilic ILs) and acetone were used in the DLLME step as the chelating agent, extraction and dispersive solvents, respectively. Using a microwave assisted-UV system, organic mercury (R-Hg) was converted to Hg(II) and total mercury amount was measured in blood samples by the presented method. Total arsenic content was determined by reducing As(V) to As(III) with potassium iodide and ascorbic acid in a hydrochloric acid solution. Finally, As(V) and R-Hg were determined by mathematically subtracting the As(III) and Hg(II) content from the total arsenic and mercury, respectively. Under optimum conditions, linear range and detection limit (3σ) of 0.1–5.0 µg L^?1 and 0.02 µg L^?1 for As(III) and 0.15–8.50 µg L^?1 and 0.03 µg L^?1 for Hg(II) were achieved, respectively, at low RSD values of < 4% (N = 10). The developed method was successfully applied to determine the ultra-trace amounts of arsenic and mercury species in blood samples; the validation of the method was performed using standard reference materials.     

Novel thionin-functionalised core shell magnetic nanoparticles for dispersive solid-phase extraction of Hg(II) in food and water samples

To develop an accurate and precise method for separation and pre-concentration of Hg(II), a novel thionin functionalised core shell structure magnetic material has been prepared and characterised. The extraction ability of the material was evaluated by magnetic solid-phase extraction coupled with inductively coupled plasma mass spectrometry determination of Hg(II) in food and water samples. Combining the advantages of magnetic separation with selective extraction of thionin towards Hg(II), the material exhibits enhanced enrich selectivity and efficiency for Hg(II). The experimental parameters influencing Hg(II) extraction efficiency, including pH of the aqueous solution, the dosage of the adsorbent, extraction time and sample volume, were systematically investigated. Under the optimised conditions, concentration of Hg(II) at 1.0 μg L^?1 can be successfully enriched by the material without the interference of the common co-existing ions. The enrichment factor and adsorption capacity were 250 and 75.2 mg g^?1, and precise of the method was confirmed by analysing the spiked food, water samples and standard water reference samples with the recoveries of 92.5–101.8%.     

Low level mercury analysis by neutron activation analysis

During the years 1974–77 about 200 low level mercury analyses on samples with less than 1000 ng Hg/kg were made at the Danish Isotope Centre. This paper describes our method of neutron activation analysis for low level mercury analysis. The accuracy of the mercury analyses is shown by the results of the determinations on NBS standard, SRM 1642, and on intercalibration analyses. The accuracy found is better than 10% for samples with about 100–300 ng Hg/kg and better than 10 ng Hg/kg for samples with less than 100 ng Hg/kg. The limit of detection for the analyses is about 1–5 ng Hg/kg, depending on the sample and the exact method of analysis. The lowest standard deviations on duplicate analyses are about 1 ng Hg/kg. The general level found in sea water is about 10 ng Hg/kg, in ground water about 50 ng Hg/kg, and in rain water about 100 ng Hg/kg.     

Determination of mercury(II) traces in drinking water by inhibition of an urease reactor in a flow injection analysis (FIA) system

 The integration of an urease reactor into a gas diffusion flow injection system was investigated for the determination of urease inhibitors. The enzyme was immobilized by entrapping in polyacrylamide gel. Besides copper and silver ions mercury ions inhibit the conversion of urea to carbon dioxide and ammonia catalysed by urease. The pH change of the carrier solution caused by the ammonia released was measured potentiometrically with a pH electrode. The inhibition behaviour of Hg(II) ions was investigated. A linear range from 2 to 20 μg L^-1 Hg(II) was obtained after a 90 s inhibition, with a correlation coefficient of r=0.9997. The relative standard deviation was 1.4% for five measurements of 2 μg L^-1Hg(II). A sample frequency of 7 h^-1 was achieved. The inhibited enzyme can be reactivated. The method was applied to the determination of Hg(II) in two drinking water samples. Received: 16 April 1996/Revised: 3 June 1996/Accepted: 11 June 1996     

Behavior of three atmospheric tracers in a pilot-scale coal combustor

Solutions of three useful atmospheric particle tracer materials, i.e., isotopically-enriched ¹⁹⁶Hg, and organometallic complexes of ¹⁴⁷Nd (T _1/2 = 11 d) and Ir, were dispersed into a pilot-scale coal combuster to determine partitioning between flue gas and suspended particle phases for Nd and Ir, and information on the chemical form of Hg tracer using nuclear analytical methods. Flue gas samples for ¹⁴⁷Nd, and Ir analyses were collected using cascade impactors at reduced and near flue gas temperatures; ¹⁹⁶Hg was sampled using an impinger method, and analyzed for ¹⁹⁶Hg after activation on cystine paper and by atomic absorption for total Hg. Solvent extracts of the impactor samples were also analyzed to determine the integrity of the tracer complexes. The results indicate that interaction with the particles tends to degrade the complexes, that major fractions become associated with particles, and that 96% of the Hg tracer was collected as HgCl₂, whereas, 85% of the natural Hg was collected as Hg^o.