Spectrophotometric Determination Of Mercury Research Articles

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.

Ultrasonic-assisted supramolecular solvent-based liquid phase microextraction of mercury as 1-(2-pyridylazo)-2-naphthol complexes from water samples

ABSTRACTA separation-preconcentration method based on supramolecular solvent ultrasonic-assisted liquid-phase microextraction (Ss-USA-LPME) for spectrophotometric determination of mercury as 1-(2-pyridylazo)-2-naphthol (PAN) chelates has been established. Red coloured Hg(II)-PAN hydrophobic complex was extracted into the supramolecular phase (1-decanol/THF) at pH 9.5. The extract was separated from aqueous phase by centrifugation, diluted with ethanol and determined by UV–Vis spectrophotometer at λmax = 560 nm. The influences of important analytical parameters such as pH, amount of PAN, 1-decanol and THF, sample volume and matrix effects for the quantitative recoveries were examined and optimised. Under the optimised experimental conditions, the amount of ligand, 1-decanol and THF were 1.0 × 10–4 M, 200 µL and 300 µL, respectively. The optimum time of ultrasonic bath and centrifugation were found as 2 min and 5 min. A linear calibration graph was obtained linearly in the concentration ranges of 8.3–1000 µg L−1. The preconcentration factor was obtained as 20. The limit of detection (LOD) was 2.6 µg L−1 with the relative standard deviation (RSD) of 2.4% for mercury (C = 100 µg L−1, n = 7). The validity of the developed Ss-USA-LPME technique was checked with a certified reference material of NIST 1641d. The presented method has been successfully applied to the determination of mercury in water samples.

Spectrophotometric determination of mercury(II) ions based on their stimulation effect on the peroxidase-like activity of molybdenum disulfide nanosheets

The authors describe a colorimetric method for the determination of Hg(II) ions by exploiting the peroxidase-lile activity of few-layered MoS2 nanosheets (MoS2-NSs). These were prepared by sonication-induced exfoliation of bulk MoS2 crystals in aqueous surfactant solution. The MoS2-NSs were found to acts as a peroxidase mimic that is capable of oxidizing the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) to give a blue product with an absorption maximum at 652 nm. The addition of Hg(II) strongly accelerates the kinetics of this reaction. It is shown that the enzyme mimic possesses a high affinity for TMB and a lower pseudo-Michaelis-Menten constant. The stimulating effect of Hg(II) is seriously influenced by the change of surface charge. The use of nanosheets covered with (negatively charged) polystyrene sulfonate results in a decrease in the formation of blue dye, while those covered with (cationic) poly(diallyldimethyl ammonium) ions cause a small increase. Under optimal conditions, the peroxidase-like activity of MoS2-NSs is affected by Hg(II) in the 2.0 to 200 μM concentration range. The method has a detection limit (LOD) of 0.5 μM which is much below the allowed level in cosmetics (1 ppm; ca. 5 μM). The method display excellent sensitivity, selectivity and stability. It was applied to the determination of total mercury in cosmetic samples, and results compared well with results obtained by ICP-AES.

Visual and spectrophotometric determination of mercury(II) using silver nanoparticles modified with graphene oxide

The authors describe the ultrasound-assisted synthesis of a graphene oxide-silver (GO-Ag) nanocomposite for the determination of mercury(II) (Hg(II)) using spectrophotometriy. The nanocomposite was characterized by UV-visible absorption spectra, XRD, TEM and Raman analyses. The spectral and colorimetric methods were performed for the optical determination of Hg(II). The reduction of absorption intensity with blue shift in the absorption band of Ag nanoparticles and the color change of the yellow nanocomposite solution were observed during the determination of Hg(II). The limit of detection was found to be 0.59 μM. The GO-Ag nanocomposite exhibited good selectivity toward the determination of Hg(II) in the presence of higher concentration of other environmentally relevant heavy metal ions.

Spectrophotometric determination of mercury(II) in environmental, soil, medicinal and biological samples using 2-benzoylpyridine-4-methyl3-thiosemicarbazone (BPMT)

Spectrophotometric determination of mercury(II) in environmental, soil, medicinal and biological samples using 2-benzoylpyridine-4-methyl3-thiosemicarbazone (BPMT)

Spectrophotometric determination of mercury in water samples using 2,4-dihydroxyacetophenone acetoylhydrazone

Spectrophotometric determination of mercury in water samples using 2,4-dihydroxyacetophenone acetoylhydrazone

Spectrophotometric determination of mercury(II) ion using gold nanorod as probe

A simple method for sensing mercury in aqueous solutions based on localized surface plasmon resonance was developed. Gold nanorods are aggregated in the presence of dithiothreitol. However, the strong coordination of Hg2+ with dithiothreitol results in a stable HgS covalent bond and inhibits the aggregation of the gold nanorods. The potential factors affecting the performance of the detection of Hg2+ were carefully optimized. Under the optimal conditions, the differences of ratios of absorbances at two wavelengths are directly proportional to the Hg2+ concentrations in the range of 1–50nmol/L. The limit of detection is 0.42nmol/L. The developed method shows a good selectivity for Hg2+ and can be applied to the determination of Hg2+ in water samples.

Spectrophotometric Determination of Mercury in Water Samples After Preconcentration Using Dispersive Liquid–Liquid Microextraction

A simple method for the determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction is described. The procedure is based on the extraction of mercury in the form of a complex and its subsequent determination by spectrophotometry. The complex is formed between Hg(II) and 2-(2-benzothiazolylazo)-p-cresol. The detection at 650 nm is performed directly in the metal-rich phase, which is spread on a triacetylcellulose membrane. The method eliminates the need to use a cuvet or large quantities of samples and reagents. The parameters that influence the preconcentration were studied, and the analytical characteristics were determined. The enrichment factor and the consumptive index for this method were 64 and 0.16 mL, respectively. The LOD (3.3 microg/L) and LOQ (11.1 microg/L) were also determined. The accuracy of the method was tested by the determination of mercury in certified reference materials BCR 397 (Human Hair) and SRM 2781 (Domestic Sludge). The method was applied to the determination of mercury in samples of drinking water, sea water, and river water.

Spectrophotometric determination of mercury(II) in environmental (water, soil and biological) samples using 3-methylthiophene-2-carbaxaldehyde thiosemicarbazone (3-MTAT)

Spectrophotometric determination of mercury(II) in environmental (water, soil and biological) samples using 3-methylthiophene-2-carbaxaldehyde thiosemicarbazone (3-MTAT)

Synthesis of New Bioactive Sulfur Compounds Bearing Heterocyclic Moiety and Their Analytical Applications

Some new bioactive sulfur compounds bearing heterocyclic nitrogen moieties such as 3- imino–2-thioxo-4,5-dihydro- thiazolidin – 4-one (3), 3-imino – 2-thioxo -3,4,5,6-tetrahydro-1, 3-thiazine-4, 6- (2 H)dione(4), N- substituted – pyrazol -3,5-dione (10) , 1,3 –disubstituted -2-thioxo-pyrimidin-4,6 –dione (11) and di –(3,5-diaminopyrazolin-1-yl)thioketone (13) derived from dithioc formic acid hydrazide (1) and thiocarbohydrazide (7)were prepared via condensation of compound 1 or 7 with acyclic and cyclic oxo compounds (e.g. aldehydes andketones) in 1:1 and 1:2 molar ratios, and addition of iso thiocyanate or treatment with active methylene compoundsfollowed by ring closing reactions in different media (Schemes I & II). The biocidal effect of some compoundstowards some bacteria and fungi was evaluated. Compound 4 was used as selective chelating agent forspectrophotometric determination of mercury (II) ions. The limit of detection (LOD) and quantification (LOQ) ofthe developed spectrophotometric method were found to be equal to 0.16 and 0.52 ?g mL-1 mercury (II),respectively. Compound 4 was also physically immobilized onto polyurethane foam (PUFs) and was successfullyused as solid sorbent in packed column for removal of mercury (II) ions from wastewater.

Synthesis and Application of New Resin Functionalized by Brilliant Green for Spectrophotometric Determination of Mercury in Environmental Samples

A new chelating resin was prepared by coupling Amberlite XAD-4 with brilliant green through an azo spacer, and it has been used for preconcentration and separation of mercury(II) in environmental samples prior to its determination by spectrophotometry. The sorption capacity of functionalized resin is 4.12 mg g−1. Spectrophotometric determination of Hg(II), free from the interference of almost all cations and anions found in the environmental water samples, is a notable advantage of the method. The determination of Hg(II) in wastewater and seawater was carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS).

Spectrophotometric determination of mercury(II) with sodium sulfite

A photometric procedure is developed for determining mercury(II) in aqueous media. It is based on the reaction of mercury(II) with sodium sulfite giving a product with an absorption maximum at 230 nm. The optimum conditions are found. The procedure allowed 0.5 to 13.0 μg/mL of mercury(II) to be determined for 1 min. The effect of some metal cations is estimated.

Dispersive liquid–liquid microextraction based on ionic liquid and spectrophotometric determination of mercury in water samples

A new simple and rapid dispersive liquid–liquid microextraction based on ionic liquid (IL) has been applied for the first time to preconcentrate trace levels of mercury as a prior step to its determination by spectrophotometric detection. In this method, small amount of an IL (1-hexyl-3-methylimmidazolium bis(trifluormethylsulfonyl)imid) as the extraction solvent was dissolved in acetone as the disperser solvent and the binary solution was then rapidly injected by a syringe into the water sample containing Hg cations which were complexed by 4,4′-bis(dimethylamino)thiobenzophenone (TMK) in the presence of sodium dodecyl sulphate as the anti-sticking agent. Thereby, a cloudy solution was formed and the Hg–TMK complex was extracted into the fine IL droplets. After centrifuging, the droplets of extractant were settled at the bottom of a conical test tube and the extracted phase was determined by spectrophotometry at 575 nm. Usually some parameters affect the complex formation and extraction, such as the type and volumes of extraction and disperser solvents, type and concentration of anti-sticking agent, salt concentration, pH and concentration of chelating agent, which have also been optimised for the presented method. Under optimum conditions, the enrichment factor of 18.8 was obtained from 10 mL of water. The detection limit of the method was found to be 3.9 µg L−1 and the relative standard deviation (n = 5) for 50 µg L−1 of mercury was 1.7%.

Spectrophotometric determination of mercury in water samples after cloud point extraction using nonionic surfactant Triton X-114

A cloud point extraction process using the nonionic surfactant Triton X-114 for extracting mercury from aqueous solutions was investigated. The method is based on the complexation reaction of Hg(II) with Thio-Michler's Ketone (TMK) and micelle-mediated extraction of the complex. The optimal extraction and reaction conditions (e.g., pH, reagent concentration, effect of time) were studied, and the analytical characteristics of the method (e.g., limit of detection, linear range) were obtained. Linearity was obeyed in the range of 5.0–80.0 ng mL −1 of Hg(II) ion. The detection limit of the method was 0.83 ng mL −1 of Hg(II) ion. The interference effect of some anions and cations was also tested. The method was applied to the determination of mercury in water samples.

Investigation of 3-amino-1,2,4-triazole azodye derivatives as reagents for determination of mercury(II)

AbstractThe reaction of mercury(II) with 3-(2,4-dihydroxyphen-1-ylazo)-1,2,4-triazole (HL1), 3-(2-hydroxy-5-methylphen-1-ylazo)-1,2,4-triazole (HL2), 3-(2-hydroxy-5-ethoxycarbonylphen-1-ylazo)-1,2,4-triazole (HL3), 3-(2-hydroxy-5-acetylphen-1-ylazo)-1,2,4-triazole (HL4), 3-(2-hydroxy-5-formylphen-1-ylazo)-1,2,4-triazole (HL5), and 3-(2-hydroxy-5-bromophen-1-ylazo)-1,2,4-triazole (HL6) was studied. A new, direct, and simple procedure was suggested for the spectrophotometric determination of mercury(II) based on its complexation reaction with HL1-HL6. The best reagent was found to be HL3 due to its high sensitivity and selectivity. In aqueous media of pH 9.0 containing 40 vol. % of methanol, Hg(II) reacts with HL3 to form a 1:2 (Hg(II) · HL3) complex having a sensitive absorption peak at 490 nm with the molar extinction coefficient of 3.31 × 104 L mol−1 cm−1 using 4 × 10−4 M of the reagent. Beer’s law is obeyed over the range from 0.00 µg mL−1 to 12.04 µg mL−1 of mercury(II). The proposed method was applied in the determination of mercury(II) in tap water, seawater and synthetic seawater samples, without the need of prior treatment, with satisfactory results.

Solid‐Phase Extraction and Spectrophotometric Determination of Mercury with 6‐Mercaptopurine in Environmental Samples

A highly selective, sensitive and rapid method for the determination of trace amounts of inorganic mercury based on the reaction of Hg (II) with 6-mercaptopurine and the solid phase extraction of the complex on C18 membrane disks was developed. The 6-mercaptopurine selectively reacts with Hg (II) to form a complex in the pH range of 5-8. This complex was preconcentrated by solid phase extraction with C18 disks. An enrichment factor of 100 was achieved. The molar absorptivity of the complex is 0.26 x 10(-6) L. mol(-1) cm(-1) measured at 315 nm. The Beer's law is obeyed in the concentration range of 0.002-0.048 microg mL(-1). The relative standard deviation for eleven-replicated measurement of 0.04 microg mL(-1) is 1.5 %. The detection limit is 0.001 microg mL(-1) in the water samples. The advantage of the method is that the determination of Hg (II) is free from interference of almost all the cations and anions found in environment and wastewater samples. The determination of Hg (II) in water samples of different origins and marine sediment were carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS). Also the method's accuracy was investigated by using SRM 2709. The obtained results by the present procedure were in good agreement with those of the CVAAS and certified value, so that the applicability of the proposed method was confirmed for the real samples.

Solid phase extraction and spectrophotometric determination of mercury by adsorption of its diphenylthiocarbazone complex on an alumina column

A simple method has been developed for the preconcentration of mercury based on the adsorption of its diphenylthiocarbazone complex on a neutral alumina column. The influence of acidity, eluting agents, stability of the column, sample volume and interfering ions has been investigated in detail. The adsorbed complex could be eluted using environmentally benign polyethylene glycol (PEG 400) and the concentration of mercury was determined by visible spectrophotometry at a wavelength maximum of 520 nm. A detection limit of 4 μg L −1 could be achieved and the developed procedure was successfully applied for the determination of mercury in spiked water samples and city waste incineration ash (CRM176). The preconcentration factor attainable for quantitative recovery (>95%) of mercury(II) was 100 for a 1000 mL sample volume.

Solid phase extraction and spectrophotometric determination of mercury in tobacco and tobacco additives with 5-(p-aminobenzylidene)-thiothiorhodanine

A highly sensitive, selective and rapid method for the determination of mercury based on the rapid reaction of mercury(II) with 5-(p-aminobenzylidene)-thiorhodanine (ABTR) and the solid phase extraction of the colored chelate with C18 disks has been developed. At pH 3.5 and in the presence of emulsifier-OP medium, ABTR reacts with mercury(II) to form a red chelate of a 1:2 (mercury to ABTR) molar ratio. This chelate was enriched by solid phase extraction with C18 disks and the retained chelate eluted form the disks with dimethyl formamide (DMF). An enrichment factor of 50 was achieved. In the DMF medium, the molar absorptivity of the chelate is 1.21´105 L mol-1 cm-1 at 545 nm, and Beer's law is obeyed in the 0.01~3 µg mL-1 range in the measured solution. The relative standard deviation for eleven sample replicate measurements at the 0.01 µg mL-1 level is 1.7%. This method was applied to the determination of mercury in tobacco and tobacco additives and good preconcentration was found between proposed and comparative methods results.

Solid Phase Extraction and Spectrophotometric Determination of Mercury in Tobacco and Tobacco Additives with p-Sulfobenzylidenerhodanine as Chromogenic Reagent

A highly sensitive, selective and rapid method for the determination of mercury based on the reaction of mercury(II) with p-sulfobenzylidenerhodanine (SBDR) and the solid phase extraction of the colored chelate with a C18 cartridge has been developed. In the presence of pH 3.8 acetate buffer solution and Tween-80 medium, SBDR reacts with mercury to form a red chelate of a molar ratio of 1:2 (mercury to SBDR). This chelate was enriched by solid phase extraction with a C18 cartridge and eluted from the cartridge with ethanol (containing 5% acetic acid). The enrichment factor of 50 was achieved. In the ethanol medium, the molar absorptivity of the chelate is 1.28×105 L·mol−1·cm−1 at 545 nm. Beer’s law is obeyed in the range of 0.01 ∼ 1.2 µg mL−1 in the measured solution. The relative standard deviation for eleven replicate samples of 0.01 µg mL−1 level is 1.52%. This method can be applied to the determination of mercury in tobacco and tobacco additives with good results.

Spectrophotometric determination of mercury in environmental sample and fungicides based on its complex with o-carboxy phenyl diazoamino p-azobenzene

In the present method a new reagent o-carboxyphenyl diazoamino p-azobenzene has been synthesised for the determination of mercury spectrophotometrically. The method is based on the reaction of mercury with the reagent in alkaline medium where the reagent is in the aci-form. The purple violet coloured dye–mercury complex showed an absorption maxima at 540 nm. Beer's law is valid over the concentration range of mercury from 0.08 to 0.8 μg ml −1 (0.08–0.8 ppm). The molar absorptivity and Sandell's sensitivity were found to be 2.22×10 5 mol −1 cm −1 and 0.0009 μg cm −2, respectively. The method has been successfully applied to the determination of mercury in air, water, soil and fungicide samples.