Determination Of Mercury Species Research Articles

Infrared radiation-assisted thermochemical vapor generation for mercury speciation by atomic absorption spectrometry

A simple, low-cost and sensitive technique using infrared radiation for thermochemical vapor generation coupled with atomic spectrometry was developed for the determination of mercury species in biological matrices.

Assignation of inorganic mercury and methylmercury mass fractions in a soil matrix certified reference material by two analytical methodologies based on species-specific isotope dilution mass spectrometry and chromatographic separation.

Assignment of inorganic mercury and methyl mercury mass fractions at an ultratrace level in soil certified reference material EnvCRM 03 with a complex matrix composition was undertaken. Inorganic mercury and methyl mercury contents by species-specific isotope dilution inductively coupled plasma mass spectrometry with on-line high-performance liquid chromatography or with classical off-line chromatography were established. Different extraction protocols: sequential extraction ((1) H2 SO4 /KBr/CuSO4 ; (2) dichloromethane; (3) Na2 S2 O3 ) or one-step extraction (diluted HCl) in solid-liquid systems were verified. Sequential extraction allowed quantification and separation of inorganic mercury and methyl mercury on HPLC column in one chromatographic run and were found to be (316 ± 10) μg/kg (U = 3.2%, k = 2) and (0.53 ± 0.02) μg/kg (U = 3.8%, k = 2), respectively. Extraction by diluted HCl and application of classical off-line chromatography led to the separation of methyl mercury from predominant inorganic mercury form and was found to be (0.54 ± 0.03) μg/kg (U = 5.4%, k = 2). To the best-obtained literature knowledge, there was no available soil material aimed for speciation analysis of inorganic mercury and methyl mercury so far. Both developed analytical methodologies were found to be equally sensitive and could be successfully applied for mercury species determination in samples with the complex matrix.

Mercury speciation in estuarine water using dithiol-based magnetic solid-phase extraction and cold vapor atomic fluorescence spectrometry

In this work, a method for mercury speciation using magnetic nanoparticles (MNPs) coated with dithiol and detection by cold vapor atomic fluorescence spectrometry (CV AFS) was developed. The magnetic Fe3O4 nanoparticles were coated with Al2O3 and sodium dodecyl sulfate (SDS) and functionalized with 1,3,4-thiadiazole-2,5-dithiol (TDT). The resulting functionalized MNPs (FMNPs, Fe3O4@Al2O3-TDT) were dispersed in the water samples, and the sorption performance with different mercury species was investigated. Once retained on the surface of Fe3O4@ Al2O3-TDT MNPs, the mercury species were magnetically separated from the sample and eluted with HCl. The organic mercury species were oxidized employing KBr-KBrO3 (100 and 17 mM, respectively) in an acid medium (HCl 1.0 M), and the results were expressed considering the total inorganic mercury concentration. It was successfully applied in mercury speciation analysis in the estuarine water, followed by CV AFS determination. In the proposed method under optimal conditions (pH 6), inorganic mercury was quantified in a linear range from 10 to 2000 ng L−1, with a limit of detection of 0.55 ng L−1, relative standard deviation (RSD) < 1.62%, and an enrichment factor of twelve. The recoveries in spiked estuarine water samples ranged from 94 to 106% for Hg(II), 85–91% for MeHg, 83–94% for EtHg, and 84–95% (PhHg) using two levels of concentration (100 and 500 ng L−1). The method is accurate, precise, and efficiently applied in mercury species determination in a complex matrix without laborious and time-consuming sample preparation.

Ion imprinted-carbon paste electrode as electrochemical sensor for ultra-trace recognizing speciation of mercury

Monitoring and determination of mercury species in the environment is a challenging issue. This work presents an electrochemical sensor based on voltammetric methods for selective recognition of Hg species using carbon paste electrode modified Hg2+-imprinted polymers. The ion-imprinted polymers were prepared by thermal bulk polymerization with Hg(NO3)2, 1,5-dipenylcarbazone (DPC), and ethylene glycol dimethacrylate (EGDMA) as template, ligand, and monomer, respectively. The surface properties of the electrode were characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, thermal gravimetric analysis, electrochemical impedance spectroscopy, and cyclic voltammetry. In addition, differential pulse voltammetry was used to evaluate the electrochemical properties of the proposed sensors. The designed sensor was shown a wide linear range between 0.1 and 40 μM with a limit of detection (LOD) at 70 nM (3σ). The sample analysis found that the sensor has good stability and selectivity for mercury speciation with a %recovery of 98–103 %.

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.

Simultaneous speciation analysis of mercury in marine origin samples by high performance liquid chromatography and species - specific isotope dilution inductively coupled plasma mass spectrometry

Species-specific isotope dilution inductively coupled plasma quadrupole mass spectrometry reference method and high-performance liquid chromatography were applied for simultaneous determination of mercury species in marine samples. Different extraction protocols for mercury species were tested and evaluated. It was found that after exposure to microwave energy the inorganic mercury (iHg) and methyl mercury (MeHg) can be completely extracted from marine biota sample by 4.5 mol L−1 HCl as well as by 3.0 mol L−1 HNO3 and further separated with HPLC. The obtained results for iHg and MeHg in the IAEA-461 certified reference material (CRM) clam Gafrarium tumidum biota sample were as follow: (341 ± 21) μg kg−1 or (338 ± 15) μg kg−1 and (61.3 ± 2.2) μg kg−1 (recovery of (98.4 ± 3.6) %) or (61.1 ± 2.8) μg kg−1 (recovery of (98.1 ± 4.6) %), respectively when diluted HCl or HNO3 were applied in the extraction step. However, these protocols are not applicable to marine sediment samples, where the iHg is the predominant form. Therefore, one selective extraction procedure for MeHg from sediment was applied to make possible its separation and quantification. This procedure consisted of series of subsequent extraction steps at room temperature: first with a mixture of H2SO4/KBr/CuSO4, next with organic solvent dichloromethane and as a final step one back-extraction with Na2S2O3 solution. The combination of the selective extraction with the ID calibration approach was found to be an efficient way for the simultaneous determination and separation of both MeHg and iHg species in one chromatographic run. The proposed procedure was successfully used for the determination of mercury species in the IAEA-405 sediment CRM and further applied for the simultaneous measurements of iHg and MeHg in a candidate CRM – the IAEA-475 sediment sample. The determined mass fractions were (30.1 ± 1.6) μg kg−1 and (196 ± 8) ng kg−1 for iHg and MeHg, respectively. The difference between obtained in this study results and those from the reference IAEA-475 values was 1.5% and further validated the developed in this study analytical methodology. To the best of our knowledge, this selective procedure for MeHg extraction was never used before for the simultaneous quantification of mercury species in marine sediment.

Ultrasensitive speciation analysis of mercury in waters by headspace solid-phase microextraction coupled with gas chromatography-triple quadrupole mass spectrometry

A sensitive, repeatable and inexpensive method combining headspace solid-phase microextraction (HS-SPME) with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was developed for the simultaneous speciation of mercury in water samples at trace and ultra-trace levels. The low-cost home-made polydimethylsiloxane (PDMS) fiber based on sol-gel method was used as a substitute for commercial one to extract and enrich the derivatives of inorganic mercury (Hg2+), methylmercury (MeHg) and ethylmercury (EtHg) in the headspace after derivatizing with sodium tetraphenylborate (NaBPh4) in situ. Some important parameters, such as preincubation and extraction temperature, preincubation time, extraction time and inlet temperature, were investigated. Under the optimized conditions, the limits of detection (LODs) of alkyl mercury and inorganic mercury were 0.03 and 6 ng L–1, respectively. The correlation coefficients were more than 0.994 in the range of 25.0–200 ng L–1 for Hg2+ and 0.12–80.0 ng L–1 for alkyl mercury. The recoveries of the analytes in real water samples spiked at three levels were all in the range of 76.6%-114.8%. The repeatability of all mercury species was good. For inorganic mercury spiked at the lowest quality control concentration (LQC) level, the relative standard deviation (RSD) was 12.1%, and it was less than 7.7% at higher spiked concentration. The RSDs of alkyl mercury were in the range of 3.0–8.5%. The method validation demonstrated the applicability of the proposed method, and it was finally used for the determination of mercury species in surface water and wastewater samples.

Determination of mercury species in seafood by liquid chrom tography - inductively coupled plasma mass spectrometry (LC-ICP-MS)

Liquid chromatography hyphenated with inductively coupled plasma mass spectrometry (LC&amp;shy;ICP&amp;shy;MS) was investigated to simultaneously determine three mercury species (mercury methyl mercury and ethyl mercury) in seafood samples. Important parameters such as organic solvents, flow rate of the mobile phase, 2&amp;shy;mercaptoethanol concentration, extraction time and temperature were optimized. The method was validated in term of the limit of detection, limit of quantitation, repeatability, and recovery meeting the AOAC performance requirements. The method has also been validated based on the analysis of certified standard samples DORM&amp;shy;4, then applied to determine three mercury species in 30 seafood samples. Results showed that the content of mercury species was below the maximum limit according to the QCVN 8&amp;shy;2 : 2011/BYT.

Speciation of mercury using high-performance liquid chromatography-inductively coupled plasma mass spectrometry following enrichment by dithizone functionalized magnetite-reduced graphene oxide

A facile method of magnetic solid-phase extraction high-performance liquid chromatography-inductively coupled plasma mass spectrometry (MSPE-HPLC-ICP-MS) based on a magnetic adsorbent that was prepared by simply and directly adsorbing dithizone on the surface of the magnetite-reduced graphene oxide composites was developed to preconcentrate trace mercury species in environmental samples. Parameters influencing the synthesis of the adsorbents and extraction, including the ratio of GO to iron (III) acetylacetonate, solution pH, adsorption time, desorption time and the component of the eluent, were optimized. Under the optimized conditions, the enrichment factors were 400 and 380 (400 mL water sample) for inorganic mercury (IHg) and methylmercury (MMHg), respectively. The detection limits (3δ) of the proposed method were 0.48 and 0.17 ng L−1 for IHg and MMHg. The spiked recoveries (91.5–111%) and standard deviation (<3.1%) in real water samples indicated that the method had high reproducibility and accuracy. This proposed MSPE-HPLC-ICP-MS method, with simple operation, high enrichment factors and high sensitivity, was successfully applied for the determination of mercury species at trace levels in environmental water samples, including river water, ground water, sea water and sewage effluent, and fish samples.

Immobilized Activated Carbon as Sorbent in Solid Phase Extraction with Cold Vapor Atomic Absorption Spectrometry for the Preconcentration and Determination of Mercury Species in Water and Freshwater Fish Samples.

A new preconcentration method using solid phase extraction (SPE) was developed by immobilizing dithizone (DZ) and 1,4-diphenylsemicarbazide (DPC) on oxidative activated carbon and then using this for the speciation and preconcentration of mercury species (Hg(II) and MeHg(I)) by flow injection cold vapor atomic absorption spectrometry (FI-CVAAS). The SPE experimental conditions were investigated including pH, amount of adsorbent and flow rate. The elution parameters and effect of foreign ions were also elucidated. Under the optimized conditions, the calibration graph was linear in the ranges of 0.015 - 3.0 μg L-1 of Hg(II), with a detection limit (LOD) of 0.0155 μg L-1, corresponding to three times the standard deviation (3SD, n = 20). The precision of the method, defined as percentage relative standard deviation (%RSD) for mercury was 1.25 - 3.79% at concentrations of 0.1 - 1.0 μg L-1, for which a preconcentration factor of 20 was obtained for Hg(II). The proposed method was validated by determining the mercury concentration in standard reference materials, and successfully applied to the speciation of mercury in several water and freshwater fish samples.

Identification of mercury species in minerals with different matrices and impurities by thermal desorption technique.

Because of its low concentration, its unique physico-chemical properties and the analytical difficulties associated with its measurement, the determination of mercury species in solids is not an easy task. Thermal desorption (HgTPD) is an attractive option for the identification of mercury species in solids due to its simplicity and accessibility. However, there are still issues that need to be solved for it to reach its full potential. One such issue is the availability of reference materials that will reproduce real mercury associations. The novelty of this study is the use of six uncommon mercury minerals, taken from around the world, and a sphalerite sample to expand the data base of reference materials for mercury speciation by thermal desorption at programmed temperature. In addition, by using such materials, a number of matrix effects can be ascertained. Different mercury associations were identified depending on the temperature of desorption, thereby validating the thermal desorption as a reliable technique for mercury speciation in solid samples and as a consequence improving the knowledge of the geochemistry of mercury in the environment.

Headspace In-Tube Microextraction and GC-ICP-MS Determination of Mercury Species in Petroleum Hydrocarbons

Characterization of mercury contamination in petroleum hydrocarbons (PHs) is necessary in order to assess the risk of corrosion of the processing infrastructure and to assess the level of human exposure to Hg-containing substances. Here we present an accurate and sensitive method for determination of Hg species in PHs by headspace sampling with a possibility of on-line pre-concentration using in-tube extraction (ITEX) combined with gas chromatography–inductively coupled plasma mass spectrometry (GC-ICP-MS) analysis. Mercury species were first extracted from the PHs matrix into an aqueous phase via dithizone chelation and subsequently converted with sodium tetrapropyl borate into volatile derivatives which could be sampled from the headspace prior to GC-ICP-MS analysis. For concentrations in the ng kg–1 range, the on-line ITEX method was applied, whereas the μg kg–1 range was accessible by static headspace. Quantitation of Hg species was carried out by a double isotope dilution method, with quantitative recoveries of methylmercury (MeHg, average 101 ± 5%) and inorganic mercury (InHg, average 97 ± 7%) by direct headspace injection. Average recoveries of Hg spikes after on-line ITEX pre-concentration were 95 ± 3% for MeHg and 98 ± 8% for InHg. The detection limits for MeHg and InHg were 428 and 46 ng kg–1 when measured by static headspace, and 2.4 ng kg–1 and 1.7 ng kg–1 by on-line ITEX pre-concentration. The accuracy of the pre-concentration method was demonstrated by analysis of a crude oil standard reference material (NIST 2722) certified for InHg.

Speciation analysis of mercury by dispersive solid-phase extraction coupled with capillary electrophoresis.

A pretreatment method of dispersive solid-phase extraction (DSPE) along with back-extraction followed by CE-UV detector was developed for the determination of mercury species in water samples. Sulfhydryl-functionalized SiO2 microspheres (SiO2 -SH) were synthesized and used as DSPE adsorbents for selective extraction and enrichment of three organic mercury species namely ethylmercury (EtHg), methylmercury (MeHg), and phenylmercury (PhHg), along with L-cysteine (L-cys) containing hydrochloric acid as back-extraction solvent. Several main extraction parameters were systematically investigated including sample pH, amount of adsorbent, extraction and back-extraction time, volume of eluent, and concentration of hydrochloric acid. Under optimal conditions, good linearity was achieved with correlation coefficients over 0.9990, in the range of 4-200μg/L for EtHg, and 2-200μg/L for MeHg and PhHg. The LODs were obtained of 1.07, 0.34, and 0.24μg/L for EtHg, MeHg, and PhHg, respectively, as well as the LOQs were 3.57, 1.13, and 0.79μg/L, respectively, with enrichment factors ranging from 109 to 184. Recoveries were attained with tap and lake water samples in a range of 62.3-107.2%, with relative standard deviations of 3.5-10.1%. The results proved that the method of SiO2 -SH based DSPE coupled with CE-UV was a simple, rapid, cost-effective, and eco-friendly alternative for the determination of mercury species in water samples.

Utility of ultrasound assisted-cloud point extraction and spectophotometry as a preconcentration and determination tool for the sensitive quantification of mercury species in fish samples

The current study reports, for the first time, the development of a new analytical method employing ultrasound assisted-cloud point extraction (UA-CPE) for the extraction of CH3Hg+ and Hg2+ species from fish samples. Detection and quantification of mercury species were performed at 550nm by spectrophotometry. The analytical variables affecting complex formation and extraction efficiency were extensively evaluated and optimized by univariate method. Due to behave 14-fold more sensitive and selective of thiophene 2,5-dicarboxylic acid (H2TDC) to Hg2+ ions than CH3Hg+ in presence of mixed surfactant, Tween 20 and SDS at pH5.0, the amounts of free Hg2+ and total Hg were spectrophotometrically established at 550nm by monitoring Hg2+ in the pretreated- and extracted-fish samples in ultrasonic bath to speed up extraction using diluted acid mixture (1:1:1, v/v, 4molL−1 HNO3, 4molL−1 HCl, and 0.5molL−1 H2O2), before and after pre-oxidation with permanganate in acidic media. The amount of CH3Hg+ was calculated from difference between total Hg and Hg2+ amounts. The UA-CPE method showed to be suitable for the extraction and determination of mercury species in certified reference materials. The results were in a good agreement (with Student's t-test at 95% confidence limit) with the certified values, and the relative standard deviation was lower than 3.2%. The limits of detection have been 0.27 and 1.20μgL−1, for Hg2+ from aqueous calibration solutions and matrix-matched calibration solutions spiked before digestion, respectively, while it is 2.43μgL−1 for CH3Hg+ from matrix-matched calibration solutions. A significant matrix effect was not observed from comparison of slopes of both calibration curves, so as to represent the sample matrix. The method was applied to fish samples for speciation analysis of Hg2+ and CH3Hg+. In terms of speciation, while total Hg is detected in range of 2.42–32.08μgkg−1, the distribution of mercury in fish were in range of 0.7–11.06μgkg−1 for CH3Hg+ and in range of 1.72–24.56μgkg−1 for Hg2+.

Automated dispersive liquid-liquid microextraction coupled to high performance liquid chromatography - cold vapour atomic fluorescence spectroscopy for the determination of mercury species in natural water samples

An automated, home-constructed, and low cost dispersive liquid-liquid microextraction (DLLME) device that directly coupled to a high performance liquid chromatography (HPLC) – cold vapour atomic fluorescence spectroscopy (CVAFS) system was designed and developed for the determination of trace concentrations of methylmercury (MeHg+), ethylmercury (EtHg+) and inorganic mercury (Hg2+) in natural waters. With a simple, miniaturized and efficient automated DLLME system, nanogram amounts of these mercury species were extracted from natural water samples and injected into a hyphenated HPLC-CVAFS for quantification. The complete analytical procedure, including chelation, extraction, phase separation, collection and injection of the extracts, as well as HPLC-CVAFS quantification, was automated. Key parameters, such as the type and volume of the chelation, extraction and dispersive solvent, aspiration speed, sample pH, salt effect and matrix effect, were thoroughly investigated. Under the optimum conditions, linear range was 10–1200ngL−1 for EtHg+ and 5–450ngL−1 for MeHg+ and Hg2+. Limits of detection were 3.0ngL−1 for EtHg+ and 1.5ngL−1 for MeHg+ and Hg2+. Reproducibility and recoveries were assessed by spiking three natural water samples with different Hg concentrations, giving recoveries from 88.4–96.1%, and relative standard deviations <5.1%.

Ultrasound-assisted dispersive micro solid-phase extraction with nano-TiO2 as adsorbent for the determination of mercury species

The combination of ultrasound-assisted dispersive micro solid-phase extraction (USA DMSPE), with the use of TiO2 nanoparticles (NPs) as adsorbent, with cold vapor atomic absorption spectrometry (CV AAS) is proposed for preconcentration and determination of mercury species (Hgtotal, Hg2+ and CH3Hg+) in biological, geological and water samples. The experimental parameters including the amount of TiO2 NPs, pH of sample solution, ultrasonication and centrifugation time, TiO2 slurry solution preparation before injection to CV AAS were investigated. Effective preconcentration of trace mercury with 10mg of TiO2 was achieved in pH 7.5. After extraction, adsorbent with analytes was mixed with 500μL of 1molL−1 HNO3 to prepare slurry solution. The concentration limit of detection was 0.004ngmL−1 for Hg2+. The achieved preconcentration factor was 35. The relative standard deviations (RSDs, %) for mercury species in real samples were 4–20%. The accuracy of this method was evaluated by analyses of certified reference materials: DOLT-2 (Dogfish Liver), IAEA-085 (Human hair), SRM 2709 (San Joaquin Soil), SRM 2711 (Montana Soil) and SRM 2704 (Buffalo River Sediment). The measured mercury species contents in reference materials were in satisfactory agreement with the added amounts (according to the t-test for a 95% confidence level). The presented method has been successfully applied for the determination of mercury species in real water samples (lake and river water).

Application of flow injection–green chemical vapor generation–atomic fluorescence spectrometry to ultrasensitive mercury speciation analysis of water and biological samples

A simple, non-chromatographic and green method based on flow injection UV photochemical or ultrasonic vapor generation atomic fluorescence spectrometry (AFS) was developed for the determination and speciation analysis of mercury. Mercury cold vapor (Hg0) was generated by using only formic acid and UV or ultrasonic irradiation, and was subsequently detected by AFS. Both mercury (Hg2+) and methyl mercury (MeHg) can be converted to Hg0 for the determination of total mercury with UV irradiation, while only Hg2+ can be reduced to Hg0 with ultrasonic irradiation, thus determining only Hg2+. Then, the concentration of MeHg can be calculated by subtracting the Hg2+ concentration from the total mercury concentration. The optimal conditions for the best cold vapor generation efficiencies are discussed in detail, together with interference from transition metals. This new speciation analysis not only provides high sensitivity for the determination of mercury species but further eliminates the use of toxic reducing reagents and avoids potential destruction of analyte species that occur in chromatographic separation. Moreover, a simpler and less toxic Hg2+ standard series can be used for the calibration of both Hg2+ and MeHg. The limit of detection is 0.005 or 0.01μgL−1 for total mercury with the UV or inorganic mercury with the ultrasonic irradiation, respectively. This method was successfully applied to ultrasensitive mercury speciation analysis of water and biological samples.

Chip-Based Magnetic Solid-Phase Microextraction Online Coupled with MicroHPLC–ICPMS for the Determination of Mercury Species in Cells

Trace mercury speciation in cells is critical to understand its cytotoxicity and cell protection mechanism. In this work, we fabricated a chip-based magnetic solid-phase microextraction (MSPME) system, integrating a cell lysis unit as well as a sample extraction unit, and online combined it with micro high-performance liquid chromatography (microHPLC)-inductively coupled plasma mass spectrometry (ICPMS) for the speciation of mercury in HepG2 cells. Magnetic nanoparticles with sulfhydryl functional group were synthesized and self-assembled in the microchannels for the preconcentration of mercury species in cells under an external magnetic field. The enrichment factors are ca. 10-fold, and the recoveries for the spiked samples are in the range of 98.3-106.5%. The developed method was used to analyze target mercury species in Hg(2+) or MeHg(+) incubated HepG2 cells. The results demonstrated that MeHg(+) entered into the HepG2 cells more easily than Hg(2+), and part of the MeHg(+) might demethylate into Hg(2+) in HepG2 cells. Besides, comprehensive speciation of mercury in incubated cells revealed different detoxification mechanisms of Hg(2+) and MeHg(+) in Hg(2+) or MeHg(+) incubated HepG2 cells.

Highly Selective Fluorescent Probe for the Sensitive Detection of Inorganic and Organic Mercury Species Assisted by H2O2

Mercury (Hg) and its derivatives pose a serious threat to the environment and human health because of their durability, easy transference, and high biological accumulation. Thus, the development of methods for selective and sensitive determination of Hg2+ is very important to understand its distribution and implement more detailed toxicological studies. Herein, we report a simple 4-hydroxynaphthalimide-derived fluorescent probe (1) for the detection of both inorganic and organic mercury species in aqueous solution. Probe 1 could quantificationally detect mercury species by fluorescence spectroscopy with high selectivity and sensitivity. Importantly, probe 1 could serve as a “naked-eye” indicator for mercury species and exhibited a large fluorescent enhancement with the help of hydrogen peroxide (H2O2). Additionally, the mechanism of the reaction between probe 1 and mercury species was confirmed using 1H NMR and ESI-MS. And, analytical applications of probe 1 to the river water samples further demonstrated that it provided an excellent method for the determination of mercury species in the environment.

Determination of Mercury Species in Fish and Seafood by Gas Chromatography-Mass Spectrometry: Validation Study

The validation of a method to identify and quantify methylmercury and ethylmercury by liquid-liquid extraction with hexane and determination by using gas chromatography coupled to mass spectrometry was evaluated. The method was validated according to EU Commission Decision 2002/657/EC. Certified reference materials NIST 2976 (mussel tissue) and NMIJ 7402-a (cod fish tissue) and an “in house” full matrix were used. Fractional factorial design was applied, whereas six experimental factors at two levels were employed. Analyses were carried out by two analysts and the intra-days and inter-days significance were considered, thus demonstrating that this method is adequate for the purpose in hand. The decision limits (CCα) and detection capability (CCβ) of the method were 13.88 and 14.55 μg L−1 for methylmercury and 15.74 and 16.07 μg L−1 for ethylmercury, respectively. Accuracy and precision were evaluated by means of recovery experiments at three concentration levels (20, 30, and 40 μg L−1), obtaining recoveries between 70 and 120 % and a coefficient of variation below 10 %. The validated method was successfully applied for determination of methylmercury and ethylmercury in canned tuna, fresh fish, and seafood samples obtained from local markets in Medellin, Colombia.