Determination Of Mercury In Water Research Articles

Bionanomaterial composed of Bradyrhizobium japonicum and graphene oxide for determination of mercury in water and fruit juice samples

In the present work, the synthesis of a novel hybrid bionanomaterial formed by the bacteria Bradyrhizobium japonicum (BJ) and the graphene oxide (GO) nanomaterial implemented in the miniaturized dispersive microsolid phase extraction technique (D-μ-SPE) was reported for the first time for the preconcentration and determination of Hg in water and fruit juice samples after a multivariate optimization. Selective Hg extraction was achieved by forming a complex with ammonium pyrrolidinedithiocarbamate (APDC) reagent and a multivariate study was performed to optimize the experimental conditions. The optimal Hg extraction conditions for 25 mL of sample were 3 mg of BJ@GO, NaNO3 at 1% (w/v), 6 min of vortex agitation and 9 min of centrifugation. For back extraction, 500 µL of 14 mol L−1 HNO3, 6 min of vortex agitation and 6 min of centrifugation were used followed by detection by cold vapor atomic fluorescence spectrophotometry (CV-AFS). Under optimized experimental conditions, an extraction efficiency of 98%, a detection limit of 0.08 µg L−1, a relative standard deviation of 3.5% (at 1 µg L−1 of Hg, n = 10), and a linear range of 0.26 - 4.0 µg L−1 were obtained. In addition, the sustainability of the method developed through the use of the Analytical GREEnness calculator (AGREE) software was evaluated, obtaining a greenness degree of 0.59. This work reports the first application of BJ@GO along with the D-μ-SPE technique for trace Hg determination water and fruit juice samples. In this way, this research work allows the exact and precise determination of low Hg concentrations in water and juice samples, which allows the evaluation of the contamination degree by this toxic metal in beverages widely consumed by the population.

Solid Phase Photothermo-Induced Chemical Vapor Generation: A New Desorption Method for Mercury Analysis by High-Throughput 20-Fiber Direct Immersion Solid Phase Microextraction.

A simple solid phase photothermo-induced chemical vapor generation (SP-PT-CVG) is described and used as an environmentally friendly desorption method for the sensitive determination of mercury in water by direct immersion solid phase microextraction (DI-SPME) atomic fluorescence spectrometry (AFS). A DI-SPME array equipped with 20 nano-TiO2-coated tungsten fibers was employed to simultaneously preconcentrate mercury from 20 samples, enabling an extraction throughput of 40 samples per hour. Subsequently, the fibers were drawn from the sample solutions and inserted into an inner tube sealed in a specially designed UV lamp in turn for SP-PT-CVG to generate Hg0, which was swept to an AFS detector for its detection. It is worth noting that the tube served as both a vapor generator and a desorption chamber. This proof-of-concept study confirms the feasibility of solid phase CVG. Compared to conventional CVG carried out in the liquid phase, solid phase CVG not only retains the advantages of conventional CVG but also alleviates the matrix interference on vapor generation and preconcentrates analyte prior to vapor generation, improving analytical performance for liquid state samples. DI-SPME-SP-PT-CVG-AFS provides a limit of detection of 2.3 ng L-1 for mercury determination by AFS. In the proposed method, the combination of DI-SPME and SP-PT-CVG eliminates the tedious derivatization steps required in conventional headspace SPME, thus minimizing toxic reagent consumption and improving extraction throughput. The practicality of DI-SPME-SP-PT-CVG-AFS was evaluated by analyzing two different certified reference materials and river water samples with good spike recoveries (98-107%).

Ultrasensitive and selective determination of mercury in water, beverages and food samples by EDXRF and TXRF using graphene oxide modified with thiosemicarbazide

The paper presents novel analytical methods for sensitive mercury determination in various samples, i.e., waters, beverages, seafood, plants, and biological samples. The procedure is based on selective preconcentration/separation of Hg(II) ions using graphene oxide/thiosemicarbazide in dispersive micro-solid phase extraction (DMSPE) and detection by energy-dispersive (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The DMSPE/EDXRF and DMSPE/TXRF procedures are characterized by very high enrichment factors and low detection limits (LODs). DMSPE/TXRF allows obtaining LODs of 2.1 pg mL−1 for liquids and 1.8 ng g−1 for solid samples. In the case of DMSPE/EDXRF, the LODs are higher, 60 pg mL−1 for liquid and 73 ng g−1 for solid samples, due to the worse sensitivity of EDXRF measurement. The method was validated using spiked samples (water, apple juice, beer, wine) and certified reference materials (seawater, groundwater, wastewater, herring, cormorant and cod tissues, pig kidney, lobster, tobacco, scallion, celery, and spinach).

Gold–Copper Film Electrode for Voltammetry Determination of Mercury in Water

Gold-copper film electrode prepared in situ on carbon paste solid disk substrate (Au–CuF/CPE) was studied as a working electrode. The factors influencing mercury stripping peak currents, such as C Au III (0.20 mg/L), C Cu II (0.05 mg/L), type of acids and their concentration (HClO4, 0.005 M), deposition potential (-800 mV) for Au–CuF/CPE, deposition time (180 s), and interferents, were investigated and optimized. The method has a low limit of detection of 0.13 μg/L and is not affected significantly by the examined ions/substance. It was applied to detect the concentration of Hg in real water samples and is promising for practical usage.

Interference from Soluble Iron on Mercury Determination in Water by Cold Vapor Atomic Absorption Spectrometry (CV-AAS) with Sodium Borohydride as Reductant.

This study demonstrated the signal enhancement interference from soluble iron (Fe) during mercury (Hg) determination in water by cold vapor atomic absorption spectrometry (CV-AAS) using sodium borohydride (NaBH4) as reductant. In the presence of 50 mg L-1 soluble Fe, Hg values will be overestimated by around 25%. The reason for the Hg signal enhancement is still unclear, but it is speculated to be attributable to the catalyst function for the equilibrium reduction reaction between Hg2+ and BH4- from the atomic Fe formed at the same time. Using the matrix matching calibration standards prepared in 50 mg L-1 Fe solution, the problem of Hg overestimation could be minimized. This study also indicated that stannous chloride (SnCl2), another common reductant for Hg analysis, does not suffer from the overestimation problem from soluble Fe in the presence of NaBH4.

Preconcentration and spectrophotometric determination of mercury in water, food and hair samples through ionic-liquid induced micelle-mediated extraction

A new, eco-friendly, and rapid micelle-mediated preconcentration technique was described for trace mercury in water, food and hair samples perior to its spectrophotometric determination. The developed method depended on cloud point extraction supported with ionic liquid (IL-CPE) for extraction of mercury utilizing a nonionic surfactant (Triton X-114) and 1-hexadecyl-3-methylimidazolium chloride (C16MeImCl) ionic liquid, as an extracting phase in the presence of 5-benzyl-4-[4-methoxybenzylideneamino)-4H-1,2,4-triazole-3-thiol (BMBATT) as a new chelating agent at pH 7.0. The influence of varous analytical variables on improving the extraction performance was tested. In the range of 2.0-600 µg L−1, the calibration curve was linear with correlation coefficient of 0.9997. The detection limit and preconcentration factor were 0.4 µg L−1 and 100, respectively. The reliability and precision of the developed IL-CPE system as the relative standard deviation (RSD %) of 100 and 400 µg L−1 mercury were in the range 1.0 and 2.4%, respectively (n=10). The validity of the developed IL-CPE approach was confirmed by the analysis of certified reference materials (NIST-1641d mercury in natural water and NCS ZC81002B human hair). The applicability of proposed IL-CPE technique was demonstrated successfully by estimation of trace mercury in real water, food and hair samples.

Modified 3D-printed device for mercury determination in waters

3D printing technology is increasingly used in flow analysis, to develop low cost and tailor-made devices. The possibility of grafting specific molecules onto 3D printed parts offers new perspectives for the development of flow systems. In this study, a MPFS system including a dicarboxylate 1,5-diphenyl-3-thiocarbazone grafted 3D-printed device has been developed for mercury determination. For this purpose, the surface of 3D-printed cuboids was first modified with amine functional groups and then grafted with dicarboxylate 1,5-diphenyl-3-thiocarbazone. This new grafted device resulted in selective mercury preconcentration with extraction and elution yields higher than 90% even at high sampling flow rates. The detection can then be carried out in two ways: a direct detection of mercury extracted onto 3D-printed grafted cuboids by atomic absorption spectrophotometry after amalgam on gold or a detection of mercury in solution after elution with l-cysteine by spectrophotometry or cold vapour atomic absorption spectrometry.

Determination of Mercury Impurities in Protamine Sulfate Medicament by Stripping Voltammetry

Introduction. The article presents data of the quantitative mercury determination in an aqueous solution of the pharmaceutical substance protamine sulfate by stripping voltammetry on graphite electrodes modified with a gold-polymer composition. The existing method to determine the mercury impurity in protamine sulfate according to the European Pharmacopoeia – multistage titration with dithizone – is laborious and does not allow to achieve repeatability.Aim. Analyzing the content of bioaccumulative mercury impurities in a protamine sulfate solution by stripping voltammetry. Materials and methods. Protamine Sulfate Substance (Manufacturer Alps Pharmaceutical Industry Co.Ltd). Experimental data were obtained on a TA-4 semi-automatic analyzer (OOO NPP Tomianalit, Tomsk) with VALabTx software.Results and discussion. We adapted the method for mercury determination in water and presented the results of its testing on protamine sulfate solution. The results of testing the electrode operation using the «entered-found» method are given, the results of a single mercury analysis were included in the interval 0, 0038–0,0063 mg/l, which confirms their readiness for work. This interval is registered in the methodology and means the limits of permissible deviations. The limits of detection of mercury on the device are 10-6 –10-10 mol/l. We prepared a solution with concentrations of 10 mg/m from the protamine sulfate substance and measured it on prepared electrodes. The mercury content in the test sample was 0.00034 mg/l. According to the certificate of protamine sulfate, the mercury content should be ≤10 ppm. We studied the effect in changing of accumulation time. The optimal accumulation time was 80 seconds, because under standard conditions, not all mercury concentrates on the electrode surface, and above 80 seconds there is no significant increase in mercury content.Conclusion. The proposed method for mercury determination in water by stripping voltammetry on graphite electrodes modified with a gold-polymer composition can be adapted to determine bioaccumulative mercury in the pharmaceutical substance protamine sulfate. The findings suggest that this method can be used in quality control of medicines, as an alternative express method for mercury impurities determination to the existing multistage titration method with dithizone.

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.

Speciation of mercury in water and freshwater fish samples using two-step hollow fiber liquid phase microextraction with electrothermal atomic absorption spectrometry

A novel method for trace inorganic mercury (Hg2+) and methylmercury (MeHg) speciation was developed utilizing two-step hollow fiber liquid phase microextraction (two-step HF-LPME) procedures with two/three phases combined with electrothermal atomic absorption spectrometry (ETAAS). This allowed for consecutive determination of MeHg and Hg2+ in water and fish samples. MeHg was firstly extracted into a polypropylene hollow fiber containing toluene by HF(3)-LPME, Na2S2O3 was then injected inside the fiber lumen as an acceptor phase to trap the analyte, while Hg2+ still existed in the aqueous solution. For Hg2+ determination, HF(2)-LPME procedure was subsequently applied after Hg2+ was chelated with diethyldithiocarbamate (DDTC) and then Hg2+-DDTC was extracted using 1-octanol. The key parameters and ETAAS profiles were investigated and optimized. This method was then applied to mercury speciation in several real-world samples and the recoveries of these samples including a standard reference material (SRM-1566b). This led to LODs of 0.14 and 0.06 μg L−1 with 2.3 and 3.7% RSD (n = 6) achieved with enrichment factors of 103 and 95 for Hg2+ and MeHg, respectively. The developed method was then evaluated and compared to other analytical techniques for mercury determination in water and fish samples.

Magnetic dispersive solid phase extraction with graphene/ZnFe2O4 nanocomposite adsorbent for the sensitive determination of mercury in water and fish samples by cold vapor atomic absorption spectrometry

In this study, the magnetic graphene/ZnFe2O4 composite material was synthesized and characterized by X-ray diffraction, scanning electron microscopy equipped with energy dispersive (X-ray spectrometry), Brunauer, Emmett and Teller surface area and zeta potential measurements. This material was investigated for the first time as an adsorbent for the magnetic dispersive solid phase extraction of Hg(II) ions from various samples. Mercury determination in solutions was made by using cold vapor atomic absorption spectrometry. The experimental conditions affecting the preconcentration of mercury were optimized. They were found as follows: sample pH, 6; adsorption and elution contact time, 3 min; elution solvent, 5 mL of 2 mol L−1 HCl. The preconcentration factor, detection limit, and precision (as RSD%) of the method were found to be 30-fold, 10 ng L−1, and 2.7% for mercury, respectively. The developed method was successfully verified by analyzing certified reference materials (DOLT-4 Dogfish Liver and NCS ZC 81002b Human Hair) and by recovery experiments in SPS-WW1 wastewater, tap water, well water, wastewater and fish samples.

A highly sensitive eco-scale method for mercury determination in water and food using photochemical vapor generation and miniaturized instrumentation for capacitively coupled plasma microtorch optical emission spectrometry

A sensitive method with a green profile for Hg determination in food and water was developed.

Electromembrane extraction-preconcentration followed by microvolume UV-Vis spectrophotometric determination of mercury in water and fish samples.

Electromembrane extraction technique combined with microvolume UV-Vis spectrophotometric detection was proposed for the preconcentration-determination of mercury in water and fish samples. The optimized conditions for preconcentration step were: the applied potential 70V, bis(2-ethylhexyl) phosphate as the extractant in 1-octanol 2% v/v, extraction time 10min, stirring rate 700rpm, acceptor and donor solutions pH 3 and 7, respectively. The linear range was found to be 2.3-950.0μgL-1 and 40-9500μgkg-1 in water and fish samples, with corresponding detection limits of 0.7μgL-1 and 12μgkg-1, respectively. The method showed satisfactory repeatability and reproducibility (CV<6%). Methodological validation was performed by using cold vapor atomic absorption spectroscopy. The proposed method provided a rapid, sensitive and accurate method which is applicable for routine analysis of total mercury contents in water and fish samples.

Ultrasensitive determination of mercury in waters via photochemical vapor deposition onto quartz substrates coated with palladium nanoparticles followed by total reflection X-ray fluorescence analysis

We describe a method for ultrasensitive detection of mercury (Hg) by total reflection X-ray fluorescence following photogeneration of Hg vapor and trapping onto quartz substrates coated with nanostructured palladium. The nanostructured coating was characterized by transmission electron microscopy. Hg vapor was generated by online photo-UV reduction in the presence of acetic acid, which acts as a precursor for reducing species. Trapping of Hg occurred as a result of amalgamation. A trapping time of 30 min and an acetic acid concentration of 2 mol L−1 provided the best results. An enrichment factor of 127 and a limit of detection as low as 54 ng L−1 of Hg were achieved. The repeatability of the method (expressed as the relative standard deviation at a level of 1 μg L−1) was 3 %. The method was successfully applied to the determination of Hg in water samples spiked with 10 μg L−1 of Hg. Recoveries ranged from 96 to 101 %.

X-ray fluorescence determination of mercury on foam polyurethane sorbent chemically modified by resorcin

A method of X-ray fluorescence determination of mercury in water with preliminary concentration on a foam polyurethane sorbent chemically modified with resorcin has been proposed. It has been shown that small-angle excitation of X-ray fluorescence of mercury directly in the sorbent phase makes it possible to increase the sensitivity of determination and range of linearity of the calibration curve of the sorption-X-ray fluorescence method by an order of magnitude.

Total-reflection X-ray fluorescence determination of cobalt and mercury in water using preconcentration on a polyurethane foam sorbent

A technique for X-ray fluorescence determination of cobalt and mercury in water using static and dynamic concentration in the form of thiocyanate and iodate complexes on polyurethane foam sorbents based on ethers is suggested. The possibility of the measurement of the X-ray fluorescence signal of analytes in the total external reflection mode, both in eluates and directly in the sorbent phase, is considered. The suggested approach allows one to improve the sensitivity of cobalt and mercury determination in water by 2–4 orders of magnitude in comparison with the classical sorption X-ray fluorescence techniques.

Use of nanohybrid materials as electrochemical transducers for mercury sensors

The electrochemical behavior of mercury using different nanostructured screen-printed transducers has been studied. The first underpotential deposition (UPD) was chosen as the best electrodic process to detect low amounts of mercury on gold nanostructured electrodes. Several nanostructured electrochemical transducers using carbon nanotubes, graphene oxide and gold nanoparticles were generated, characterized and optimized for mercury determination in water. The transducer with a nanohybrid surface of carbon nanotubes and gold nanoparticles was the best suited to solve the analytical problem. For this sensor, a calibration plot from 0.5 to 50μg/L was obtained in acidic solutions of Hg(II) with an intraelectrodic reproducibility of 3% (n=5). The detection limit was 0.2μg/L of mercury. The performance of the sensor was then evaluated using real samples of tap and river water with good accuracy.

Simple mercury speciation analysis by CVG-ICP-MS following TMAH pre-treatment and microwave-assisted digestion

A simple method was proposed for mercury cold vapor generation (CVG) in tetramethylammoniumhydroxide (TMAH) solution for speciation analysis of ultratrace inorganic mercury and total mercury in biological samples by inductively coupled plasma mass spectrometry (ICP-MS). Prior to analysis, 100–300mg of the biological sample was accurately weighed into a conical tube. Then, 2mL of 25% (m/v) TMAH solution was added to the sample, incubated at room temperature for several hours (hair, 3h), and diluted to 25mL with water. Finally, inorganic mercury was directly determined by CVG-ICP-MS, while microwave-assisted oxidation with H2O2 was needed for total mercury detection. The concentration of organic mercury, mainly methylmercury, was obtained by difference of total mercury and inorganic mercury. Only one calibration curve against mercury aqueous standards in 2% TMAH medium was needed for both procedures. Optimum conditions for mercury CVG, as well as sample preparation and microwave-assisted digestion were investigated in detail. A limit of detection (LOD, 3σ) of 3ngL−1 was obtained and the linear working range was 0.1–100μgL−1. Validation data were provided based on the analysis of water samples, as well as a CRM human hair sample (GBW 070601). This is a simple, rapid, ultrasensitive and relatively green method for the determination of mercury in water and biological samples.

Determination of Hg in water and wastewater samples by CV-AAS following on-line preconcentration with silver trap

An online mercury preconcentration and determination system consisting of cold vapor atomic absorption spectrometry (CV-AAS) coupled to a flow injection (FI) method was studied. The method was developed involving the determination of ng/L levels of mercury retained on the silver wool solid sorbent. Experimental conditions such as sample volume, flow rate, stability of the column and effect of foreign ions on the determination of trace amounts of mercury were optimized. The detection limit is 3 ng/L and dynamic range 10–250 ng/L require only 50 mL of sample. The relative standard deviations (RSD) of the determinations are below 4%. The presence of common metal ions, such as K+, Na+, Cu2+, Pb2+, Fe3+, Ni2+, and Mn2+, does not interfere with the measurement of mercury by this method. The method was successfully applied to the determination of mercury in water and wastewater samples.

Determination of mercury in water and fish samples by cold vapor atomic absorption spectrometry after solid phase extraction on agar modified with 2-mercaptobenzimidazole

A novel solid phase extraction method for the determination of mercury has been developed. The Hg(II) ions were retained on a mini-column packed with agar powder modified with 2-mercaptobenzimidazole at a flow rate of 6 mL min −1. The retained Hg(II) ions were eluted with 3 mol L −1 solution of HCl and measured by cold vapor atomic absorption spectrometry (CV-AAS). The effect of different variables such as pH, sample flow rate, amounts of 2-mercaptobenzimidazole loaded on agar and SnCl 2 concentration was investigated and optimum conditions were established. The calibration curve was linear in the range of 0.040–2.40 ng mL −1 with r = 0.9994 ( n = 8). The limit of detection based on three times the standard deviation (3S b) ( n = 10) obtained under optimum conditions was 0.02 ng mL −1. The relative standard deviation (R.S.D.) for the determination of 0.4 and 2.0 ng mL −1 of Hg(II) was 2.6 and 1.9% ( n = 8), respectively. The method was successfully applied to determine Hg(II) in water, wastewater and fish samples.