Determination Of Inorganic Mercury Research Articles

One-Pot Pretreatment Coupled to Microplasma Optical Emission Spectrometry for Field and Sensitive Determination of Inorganic Mercury and Methylmercury in Fish.

Field and sensitive analysis of mercury species in seafood is helpful to assess the risk of human exposure to mercury, but the cumbersome pretreatment process is time-consuming and laborious. Herein, a simple one-pot pretreatment system is designed for extraction, separation, and enrichment of inorganic mercury (Hg(II)) and methylmercury (MeHg) in fish, and coupled to dielectric barrier discharge (DBD) microplasma optical emission spectrometry (OES). Both Hg(II) and MeHg species in fish can be effectively extracted by tetramethylammonium hydroxide under ultrasound, then separated from the fish matrix by vapor generation and photochemical vapor generation, and finally enriched on the activated carbon electrode tips. Mercury trapped on the activated carbon electrode tips can be rapidly released to produce OES under the DBD microplasma excitation for quantitative analysis. The pretreatment and analysis of a batch of 12 samples are completed within 50 min, and the extraction efficiency of total mercury is up to 90% for 100 mg of freeze-dried fish or 86% for 1 g of fresh fish. Under the optimized conditions, the detection limits are 2 μg kg-1 for Hg(II) and 1.2 μg kg-1 for MeHg in freeze-dried fish, and precisions are 3.2% for Hg(II) and 3.9% for MeHg. The present method is applied to the analysis of the certified reference material and real marine fishes, giving rise to spiked recoveries of 95-103%. The present system hardly leads to MeHg and Hg(II) transforming into each other during extraction, providing a simple, convenient, and low-cost analytical tool to evaluate the risk of mercury species in fish.

Determination of methylmercury and inorganic mercury in human hair samples of individuals from Colombian gold mining regions by double spiking isotope dilution and GC-ICP-MS

With the aim to distinguish between routes of exposition to mercury (Hg) in artisanal and small-scale gold mining (ASGM) communities and to distinguish between Hg contamination sources, Hg species composition should be performed in human biomarkers. In this work, Hg species-specific determination were determined in human hair samples (N = 96), mostly non-directly occupied in ASGM tasks, from the six most relevant gold mining Colombian regions. Therefore, MeHg, Hg(II) and THg concentrations were simultaneously determined by double spiking species-specific isotope dilution mass spectrometry (IDMS) and GC-ICP-MS. Only 16.67% of participants were involved at some point in AGSM works and fish consumption ranged from 3 to 7 times/week, which is between medium and high intake levels. The median concentration of THg obtained from all samples is higher than the reference dose weekly acceptable of MeHg intake established by the EPA (1 ppm), whereas a 25% were more than 4 times higher than the WHO level (2.2 μg Hg g−1). Median THg value of individuals consuming fish 5–7 times per week was significantly higher (p < 0.05) than those of the other consuming groups (12.5 μg Hg g−1). Most of the samples presented a % of MeHg relative to THg higher than 80%. The average % of Hg(II)/THg was 11% and only 10 individuals presented a Hg(II) content over 30%. No significant differences (p > 0.05) were found when the amount of Hg(II) was compared between people involved in AGSM task and people not involved. Interestingly, significant differences among the evaluated groups where found when the percentage of the Hg(II)/THg ratio of these groups were compared. In fact, people involved in AGSM tasks showed 1.7 times higher Hg(II)/THg vs. inhabitants uninvolved. This suggest that Hg(II) determination by IDMS-GC-ICP-MS could be a good proxy for evaluating Hg(II) adsorption by direct exposure to mercury vapors onto hair.

Electrochemical Determination of Hg2+ on a Poly (Eriochrome Blue Black R) Modified Carbon Paste Electrode

In this work a new, simple, fast, and efficient electrochemical approach for the determination of inorganic mercury (Hg2+) using the differential pulse anodic stripping voltammetry (DPASV) technique was presented. This is achieved by modifying the surface of a carbon paste electrode by electropolymerization of Eriochrome blue black R. First, the behavior of Hg2+ on the modified electrode is studied by cyclic voltammetry and electrochemical impedance spectroscopy, to evaluate performance and understand the phenomena that take place on its surface. DPASV is then used to optimize the sensor in HClO4 medium. After optimization, a linear calibration graph was obtained in the concentration range of 1x10-9 to 9x10-9 mol.L-1 with correlation coefficient R2= 0.9975%, the limit of detection (LOD) and the limit of quantification (LOQ) obtained are respectively 3.23x10-10 mol.L-1 and 1.07x10-9 mol.L-1. The relative standard deviation (RSD) for 7 measurements is 3.07%, which proves that this sensor is reproducible. Finally, this method has been successfully applied in real samples of water and the results obtained are satisfactory because the recovery rates of Hg2+ vary from 99.2 to 100.1%.

On-Site Determination of Methylmercury by Coupling Solid-Phase Extraction and Voltammetry.

A measurement and speciation procedure for the determination of total mercury (HgTOT), inorganic mercury (HgIN), and methylmercury (CH3Hg) was developed and the applicability for on-site determination was demonstrated. A simple, portable sample pretreatment procedure was optimized to extract the analytes. Home-made columns, packed with a new sorbent material called CYXAD (CYPHOS 101 modified Amberlite XAD), were used to separate the two forms of the analyte. HgTOT and CH3Hg were determined by anodic stripping voltammetry (ASV), using a solid gold electrode (SGE). Two certified reference materials (BCR-463 Tuna Fish and Tuna Fish ERM-CE 464) and eight fresh fishes were analyzed. Then, the results that were obtained following the optimized portable procedure were compared with the concentrations obtained, using a direct mercury analyzer (DMA). This quantification, using the two techniques, demonstrated the good performance of the proposed method.

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 0.05ngL-1 and 0.08ngL-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±4ngL-1). The determined MeHg concentration was below MDL while iHg concentration was determined to be 41.2±0.5ngL-1. Both MeHg and iHg were also spiked to natural water samples at 5ngL-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 0.24ngL-1 and 0.50-0.62ngL-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.

Recent Trends and Future Perspectives of Emergent Analytical Techniques for Mercury Sensing in Aquatic Environments.

Environmental emissions of mercury from industrial waste and natural sources, even in trace amounts, are toxic to organisms and ecosystems. However, industrial-scale mercury detection is limited by the high cost, low sensitivity/specificity, and poor selectivity of the available analytical tools. This review summarizes the key sensors for mercury detection in aqueous environments: colorimetric-, electrochemical-, fluorescence-, and surface-enhanced Raman spectroscopy-based sensors reported between 2014-2021. It then compares the performances of these sensors in the determination of inorganic mercury (Hg2+ ) and methyl mercury (CH3 Hg+ ) species in aqueous samples. Mercury sensors for aquatic applications still face serious challenges in terms of difficult deployment in remote areas and low robustness, reliability, and selectivity in harsh environments. We provide future perspectives on the selective detection of organomercury species, which are especially toxic and reactive in aquatic environments. This review is intended as a valuable resource for scientists in the field of mercury sensing.

Determination of Mercury in Artificial Saliva Extract of Chewing Tobacco by Dispersive Liquid–Liquid Micro-Extraction Using Electrothermal Atomic Absorption Spectrometry (ETAAS)

An enrichment method was developed for the determination of inorganic mercury (Hg) in artificial saliva extracts (ASE) of frequently consuming chewing tobacco products (CTP). The artificial saliva extracts of the mainpuri and gutkha chewing tobacco were subjected to dispersive liquid-liquid micro-extraction (DLLµE) based on the ultrasound based back extraction of hydrophobic complex of inorganic mercury (iHg) separately by L-cysteine and hydrochloric acid. The total Hg, extractable Hg (EHg), and enriched inorganic mercury in artificial saliva extracts of chewing tobacco were determined by electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma – optical emission spectrometry (ICP-OES). The results obtained by these techniques were not significantly different (p > 0.05). Factors affecting the extraction efficiency of inorganic mercury such as concentration of the ligand, pH, disperser/extracting solvent, sonication time, and back extracting reagents were optimized by multivariate techniques. The precision and accuracy of total mercury (tHg) was confirmed by analyzing a tobacco certified reference material, while the validity of the proposed method (DLLµE) was ensured by spiking inorganic mercury in artificial saliva extracts of the chewing tobacco products. Using the optimized conditions for developed method, the limit of detection and enrichment factor for inorganic mercury were 0.17 μg/L and 96.2, respectively. The extractable Hg in artificial saliva extracts of chewing tobacco was from 35 to 48% of the total content. However, the concentration of inorganic mercury was between 68 and 80% of the total extractable concentration in artificial saliva extracts of the chewing tobacco.

Comparison of GC-ICP-MS, GC-EI-MS and GC-EI-MS/MS for the determination of methylmercury, ethylmercury and inorganic mercury in biological samples by triple spike species-specific isotope dilution mass spectrometry

We present here the comparison of three mass spectrometric techniques coupled to gas chromatography for the speciation of Hg in complex matrices in order to evaluate the limiting factors for providing accurate and precise quantification results.

Determination of Methylmercury and Inorganic Mercury in Human Hair Samples of Individuals from Colombian Gold Mining Regions by Double Spiking Isotope Dilution and Gc-Icp-Ms

Determination of Methylmercury and Inorganic Mercury in Human Hair Samples of Individuals from Colombian Gold Mining Regions by Double Spiking Isotope Dilution and Gc-Icp-Ms

Field determination of inorganic mercury in seawaters by a portable dual-channel and purge-and-trap system with atomic fluorescence spectrometry

ABSTRACT An on-line flow injection mercury analyser (FIMA) for inorganic mercury (Hg) analysis in environmental waters is presented. The FIMA is a portable dual-channel and purge-and-trap system combining aqueous reduction with stannous chloride (SnCl2), two-stage gold (Au) amalgamation, thermal desorption of Hg0 and final detection with cold vapour atomic fluorescence spectrometry (CVAFS). Simultaneous on-line operations of sample loading and analysis make analytical throughput and accuracy improved and contamination eliminated. Results of system optimisation and reliability regarding the determination of inorganic Hg2+ are described. Analytical performances of both channels were the same in terms of data reliability. Low procedural blanks were obtained from laboratory and field trip (≤5 pg, n = 30). Excellent calibrations (r2 > 0.99) with a high precision and good stability (RSD <5%, n = 30) were obtained. Detection limits and reproducibility of the methods have been estimated as ≤0.05 ng L−1 and <5% (0.5 ng L−1, n = 30). The system was finally validated by measurements comparison of the two channels (r2 > 0.98), and analysis of a certified reference material (coastal seawater BCR-579, recoveries 101 ± 4%, n = 10). Overall, a sample throughput of ~10 samples per hour with two-channel detections of FIMA can be achieved. The onboard analysis of inorganic Hg species (e.g. elemental, reactive, and total Hg) in surface seawaters of the East China Sea (ECS) are also successfully achieved. The portable FIMA is fast, easy, and robust for reliable monitoring of Hg in natural seawaters.

Magnetic solid-phase extraction based on sulfur-functionalized magnetic metal-organic frameworks for the determination of methylmercury and inorganic mercury in water and fish samples

A novel magnetic metal-organic frameworks (Fe3O4@UiO-66-SH) was successfully prepared by coating Fe3O4 nanospheres with sulfur-functionalized UiO-66. The Fe3O4@UiO-66-SH possesses both the magnetic properties of Fe3O4 and the diverse properties of metal-organic framework (MOF) in one material, which has the superiority of high surface area, easy-operation and strong adsorb ability with mercury, is used for the magnetic solid-phase extraction of methylmercury (MeHg+) and inorganic mercury (Hg2+) in water and fish samples. The analyzes were conducted by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The different pretreatment conditions influencing the extraction recoveries of Hg2+ and MeHg+, including adsorbent amount, pH, extraction time, elution solvent, elution volume, desorption time, co-existing ions and dissolved organic materials were investigated. Under the optimized conditions, the limits of detection (LODs) of Hg2+ and MeHg+ for water samples were 1.4 and 2.6 ng L−1, and the limits of quantification (LOQs) of Hg2+ and MeHg+ for water samples were 4.7 and 8.7 ng L−1. The enrichment factors (EFs) were 45.7 and 47.6 fold for Hg2+ and MeHg+, respectively. The accuracy of the proposed method was demonstrated by analyzing the certified reference material of fish tissue (GBW10029) and by determining the analyte content in spiked water and fish samples. The determined values were in good agreement with the certified values and the recoveries for the spiked samples were in the range of 84.5–96.8%.

Ultrasound-assisted dual-cloud point extraction with high-performance liquid chromatography-hydride generation atomic fluorescence spectrometry for mercury speciation analysis in environmental water and soil samples.

A method for simultaneous preconcentration and determination of mercury species in water and soil samples was established using high-performance liquid chromatography with hydride generation atomic fluorescence spectrometry after ultrasound-assisted dual-cloud point extraction. The extraction process was divided into two steps. In the first cloud point extraction, inorganic mercury and methylmercury formed chelates with sodium diethyldithiocarbamate and were extracted into Triton X-114 micelles. In the second stage, a displacement reaction between sodium diethyldithiocarbamate-inorganic mercury/methylmercury and l-cysteine occurred, and the analytes entered the l-cysteine aqueous solution under ultrasonication. This aqueous solution was directly introduced to the high-performance liquid chromatography with hydride generation atomic fluorescence spectrometry and the detection was completed within 6min. Under the optimum experimental conditions, the linear range was 0.10-5.0 μg/L (r ≥0.9993) for inorganic mercury and methylmercury, and the enhancement factors were 15.7 for inorganic mercury and 6.35 for methylmercury. The limits of detection for inorganic mercury and methylmercury were 0.004 and 0.016 μg/L, respectively. The approach was successfully applied to the determination of trace inorganic mercury and methylmercury in water and soil samples with good recoveries (85.3-110%). This method solved the problem of peak fusion of the two analytes and was successfully applied to the speciation analysis of mercury.

Speciation analysis of mercury in wild edible mushrooms by high-performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry.

Wild edible mushrooms can accumulate significantly elevated levels of mercury from the surrounding environment, which could be harmful to consumers' health. Speciation analysis of mercury in wild edible mushrooms aids in understanding the human exposure to these toxic compounds. In this study, we developed a high-performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS)method for the simultaneous determination of inorganic mercury (Hg(II)), methylmercury (MeHg), ethylmercury (EtHg), and phenylmercury (PhHg) in wild edible mushrooms. A rapid separation of four target mercury species was achieved within 11min by a C8 column without utilizing high proportion of organic phase in HPLC. The parameters affecting the extraction efficiency of mercury in samples have been investigated. The proposed method showed good linearity within 0-50μg/L with the detection and quantification limits of 0.6-4.5μg/kg (S/N = 3), and 2.0-15μg/kg (S/N = 10), respectively. This proposed method was successfully applied to the mercury speciation analysis in 7 varieties (95 samples) of wild edible mushrooms. The results indicated that in most mushroomsamples, mercury mainly occurred as inorganic mercury. But there were two Tricholoma matsutakes, one contained 0.14mg/kg of methylmercury, another contained 1.05mg/kg of phenylmercury, which were higher than the maximum allowable content of total mercury in edible mushrooms in China. Graphical abstract.

Development of a liquid chromatography-inductively coupled plasma mass spectrometry method for the simultaneous determination of methylmercury and inorganic mercury in human blood

We developed and validated a liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) method for simultaneous determination of methylmercury (MeHg) and inorganic mercury (I-Hg) in human blood samples. Thallium was used as an internal standard for determination of MeHg and 196Hg was used as an internal standard for I-Hg determination. The blood samples were extracted using a 7% (v/v) HCl solution containing 1.5% (w/v) l-cysteine. A 10% (w/v) trichloroacetic acid solution was used to precipitate proteins in the extract. Mercury species were measured by LC-ICP-MS. The linear range of the assay was 0.08–60 ng/mL for MeHg and 0.05–2.5 ng/mL for I-Hg. The method was validated with the Certified Reference Materials Blood Mercury (Institut National de Santé Publique Québec, Quebec, Canada) and Seronorm™ Trace Elements Whole Blood (Sero AS, Billingstad, Norway). Additional validation was performed by comparing the results obtained with those from a widely used gas chromatography method with electron-capture detection. The proposed method was applied to the simultaneous determination of MeHg and I-Hg in human blood samples. The LC-ICP-MS method provides precise, accurate, and robust determination of MeHg and I-Hg levels in human blood over a long period and has a simple and quick sample preparation. We expect that this method will contribute to large-scale evaluation of human exposure to mercury compounds in future.

An efficient 2-mercapto-5-phenylamino-1,3,4-thiadiazole functionalized magnetic graphene oxide nanocomposite for preconcentrative determination of mercury in water and seafood samples

In this work, an efficient 2-mercapto-5-phenylamino-1,3,4-thiadiazole (2-MPATD) modified magnetic graphene oxide was synthesized and utilized to preconcentrative determination of inorganic mercury (Hg(II) ions) in water and seafood samples. At first graphene oxide sheets were decorated with Fe3O4 NPs to obtain magnetic graphene oxide, and then magnetic graphene oxide sheets were coated with a silica layer. Afterwards, magnetic graphene oxide@SiO2 was functionalized by 2-MPATD (mGO@SiO2@2-MPATD nanocomposite). FT-IR, SEM, elemental analysis and vibrating sample magnetometry techniques were employed to characterize the nanosorbent. Experimental design was performed to monitor and find the parameters that affect the extraction performance. After sorption and elution steps, the concentration of Hg(II) was measured by employing cold vapor atomic absorption spectrometry. The highest extraction performance was achieved under the following conditions: sorption time (10.0 min), pH value (6.3), sorbent amount (16 mg); eluent (HNO3 solution; 1.25 mol L-l; 1.7 mL), and elution time (14.0 min). The obtained detection limit was 0.008 ng mL−1. Finally, the method was utilized for rapid determination of mercury ions in various real samples, satisfactorily.

Combination of sequential cloud point extraction and hydride generation atomic fluorescence spectrometry for preconcentration and determination of inorganic and methyl mercury in water samples

A sequential cloud point extraction method was established for the determination of trace mercury species in water samples by hydride generation atomic fluorescence spectrometry (HGAFS). The proposed extraction system consisted of two chief steps: isolation of inorganic mercury (Hg2+) by chelating with potassium-iodide and methyl green, and then isolation of methyl mercury (CH3Hg+) by chelating with ammonium pyrrolidinedithiocarbamate. The nonionic surfactant Triton X-114 was chosen as the extractant, while the brominating agent was applied to convert extracted CH3Hg+ into Hg2+. Before HGAFS detection, the two surfactant-rich phases obtained in the sequential process were separately diluted to 3 mL with 5% (v/v) HCl after the addition of antifoam (0.4 mL). The effects of experimental conditions, including pH and concentration of surfactant and chelating agents, on cloud point extraction were optimized. Under the optimum conditions, the limits of detection for Hg2+ and CH3Hg+ were 0.007 and 0.018 μg/L with the enrichment factors of 15.1 and 11.2, respectively. The proposed method was successfully used for the determination of trace Hg2+ and CH3Hg+ in water samples with satisfactory recoveries of 95–104%.

Speciation of organic/inorganic mercury and total mercury in blood samples using vortex assisted dispersive liquid-liquid microextraction based on the freezing of deep eutectic solvent followed by GFAAS

In this research, a new vortex assisted dispersive liquid−liquid microextraction based on the freezing of deep eutectic solvent (VADLLME−FDES) has been developed for the determination of organic mercury (R-Hg) and inorganic mercury (Hg2+) in blood samples prior to their analysis by graphite furnace atomic absorption spectrometry (GFAAS). In this method, a green solvent consisting of 1-octyl-3-methylimidazolium chloride and 1-undecanol was used as an extraction solvent, yielding the advantages of material stability, low density, and a suitable freezing point near room temperature. Under the optimum conditions, enrichment factor is 112. The calibration graph is linear in the range of 0.30–60 µg L−1 and limit of detection (LOD) is 0.10 µg L−1. Repeatability and reproducibility of the method based on seven replicate measurements of 5.0 µg L−1 of Hg2+ in analyzed samples were 3.7% and 6.2%, respectively. The relative recoveries of blood samples which have been spiked with different levels of Hg2+ are 90–109%. A new deep eutectic solvent consists of two parts: [DMIM]Cl and 1-undecanol in the molar ratio of 1–2. The accuracy of the proposed procedure was also assessed by determining the concentration of the mercury in a standard reference material. All organic mercury (R-Hg) species were converted to Hg2+ and finally, the concentration of R-Hg is simply calculated by mathematically subtracting the concentrations of Hg2+ from the concentration of total mercury (t-Hg). The extraction methodology is simple, rapid, cheap and green since small amounts of non-toxic solvents are necessary.

Non-chromatographic separation and determination of thimerosal and inorganic mercury in vaccines by Fe3+-induced degradation with cold vapor atomic fluorescence spectrometry

By adding Fe3+ into an HCl carrier, thimerosal can be transformed into elemental mercury cold vapor in the presence of KBH4 and detected by AFS.

Fast method for the simultaneous determination of monomethylmercury and inorganic mercury in rice and aquatic plants

Recent investigations revealed that monomethylmercury (MMHg) can be absorbed and accumulated by plants, i.e. rice crops, thus becoming an important route of human exposure to MMHg through diet. The increasing concern about this fact makes that appropriate analytical methods for Hg speciation in these samples are urgently required. Therefore, the aim of this work has been the development of a fast and sensitive method which enables the simultaneous determination of MMHg and inorganic Hg in rice and aquatic plants. The proposed methodology is based on the extraction of Hg species by closed-vessel microwave heating, subsequent derivatization by ethylation and analysis by gas chromatography coupled to atomic fluorescence detection via pyrolysis (GC-pyro-AFS). A careful optimization of the extraction, using both acid (6N HNO3) and alkaline (tetramethylammonium hydroxide, TMAH) extractants, and derivatization conditions has been carried out. Spiked and unspiked aquatic plants (Typha domingensis) and CRMs certified for Total-Hg (BCR-60, BCR-482 and NCS ZC73027, corresponding to aquatic plant, lichen and rice, respectively) have been used. Under the final optimized conditions the simultaneous determination of MMHg and inorganic Hg can be carried out in less than 40min with no tedious clean-up steps. Quantitative recoveries (from 92% to 101%) were obtained in aquatic plants (Typha domingensis) and CRMs spiked with known concentrations of MMHg. For unspiked BCR-60 and BCR-482, no statistically significant differences (p=0.05) were found in Total-Hg concentrations between those obtained by the sum of species and the certified values for both acid and alkaline extraction. For the analysis of low Hg polluted samples, an additional preconcentration step by evaporation under nitrogen stream was required but adequate blanks were only obtained for acid extraction. Detection limits in the low ng/g range (0.7–1.0ng/g) were consequently achieved for both Hg species in the case of acid extraction and the analysis of NCS ZC73027 gave satisfactory results without statistically significant differences between the found and certified values (p = 0.05).

Speciation of Mercury in Microalgae by Isotope Dilution-inductively Coupled Plasma Mass Spectrometry

ABSTRACTSpecies-specific stable isotope dilution in combination with gold trap- or gas chromatography (GC)-inductively coupled plasma mass spectrometry (ICP-MS) is reported for the determination of inorganic mercury and methylmercury in diatoms (Chaetoceros curvisetus). The optimum conditions for the separation parameters were established. The isotope dilution analysis was performed using 199Hg-enriched Hg2+ and laboratory-synthesized 201Hg-enriched methylmercury. The absolute detection limits obtained with isotope dilution-ICP-MS were 9 pg for total mercury and 0.6 pg for methylmercury. The relative error of 7 Hg isotopic abundances based on the peak area measurements was better than 2.0% for 20 pg of methylmercury (as Hg) and 250 pg of inorganic mercury. The accuracy of the method was validated with a biological certified reference material. The developed method was then applied to investigate the uptake of inorganic mercury and methylmercury by C. curvisetus. Continuous uptake of inorganic mercury and methylmercury was observed during 5 days of incubation.