Simultaneous Determination Of Hg Research Articles

Cysteine-modified silica resin in DGT samplers for mercury and trace metals assessment

Diffusive gradients in thin-films (DGT) is an in situ passive sampling technique to assess labile trace metal concentrations in different environmental matrix. The technique is consisting of a diffusive domain backed up by a resin gel that binds free metals and metal complexes that dissociate in the diffusive domain. This technique requires specific resin for special metals, for example mercury (Hg), since the classic resin (Chelex-100) gel is not applicable for Hg measurement. A simultaneous determination of Hg with other metals by the DGT was not yet reported. Two biomolecule-based resins were prepared by glutaraldehyde immobilisation of cysteine onto 3-amino-functionalised silica and 3-aminopropyl-functionalised silica, respectively. The load of functional groups on modified resins was qualitatively and quantitatively characterised. The modified resins were applied in the DGT technique and the uptake efficiency, elution efficiency, and linear accumulation of analytes of the DGT were tested. This novel DGT technique, using two cysteine-modified resins, can accumulate Hg and other metals in a broad range of pH and ionic strength in solutions. In the Belgian coastal zone (BCZ), the concentrations of Hg and other trace metals sampled by cysteine-modified resin-DGTs were similar as those by the other two DGT assemblies for Hg and other trace metals, respectively. The cysteine-modified silica resin combined the features of Chelex-100 resin and 3-mercaptopropyl silica resin and allowed simultaneous determination of labile Hg and other trace metals. The resin with a higher load of functional groups also showed higher performance in the further application in the DGT technique.

Simultaneous determination of Hg(II) and Cu(II) in water samples using fluorescence quenching sensor of N-doped and N,K co-doped graphene quantum dots

The present study was aimed to use of N doped graphene quantum dots (N-GQDs) and N,K co-doped graphene quantum dots (N,K-GQDs) as a fluorescence quenching sensor to determine both mercury and copper in water sample, simultaneously using simple fluorescence protocol. Each of N-GQDs or N,K-GQDs was optimized separately with 1–5% (w/v) HNO3 or KNO3, respectively, and their quantum yields were determined and compared. It was found that N-GQDs, obtained from 3% (w/v) HNO3 doped resulted higher fluorescence intensity at the maximum excitation and emission wavelengths of 370 and 460 nm, respectively, with higher quantum yield (QY = 83.42%) compared with that of undoped GQDs (QY = 16.35%). While N,K-GQDs obtained from 5%(w/v) KNO3 gave somewhat different fluorescence spectrum, but still had the same maximum excitation and emission wavelengths with rather highest QY (94.07%). However, it is interesting that detection sensitivity expressed as slope of their calibration curve (y = 5.43x − 19.48; r2 = 0.9971) of the N-GQDs is rather higher than that (y = 1.29x + 17.66; r2 = 0.9977) of the N,K-GQDs for Hg2+ fluorescence quenching sensor, and the fluorescence intensity of N-GQDs had better selectively quenching effect only by both Hg2+ and Cu2+. Thus, their quenching effects were selected to develop the fluorescence turn-off sensor for trace level of both metal ions in real water samples. For method validation, the N-GQDs exhibited high sensitivity to detect both Hg2+ and Cu2+ with wide linear ranges of 20–100 μM and 100–500 μM, respectively. Limit of detection (LOD) and limit of quantitation (LOQ) were 0.42 μM & 1.41 μM for Hg2+ and 13.19 μM & 43.97 μM for Cu2+, respectively, with their precision expressed as an intra-day and an inter-day analysis of 6.98% & 11.35% for Hg2+ and 11.78% & 9.43% for Cu2+, respectively. Also the study of matrix analysis of the water samples (drinking water and tap water), was carried out using N-GQDs and N,K-GQDs resulted good percentage recoveries in comparison with those using undoped GQDs under the same optimum conditions.

The stripping analysis of Hg(II) and Cu(II) based on hierarchical RTIL/γ-AlOOH/Fe(OH)3 composite

It is rather important to not only obtain the better detection efficiency for metal ions, but also investigate the change of sensitivity and detection limit in the simultaneous detection. Herein, a novel type of room temperature ion liquid (RTIL)/γ-AlOOH/Fe(OH)3 composite was prepared. Both the individual and simultaneous determination of Hg(II) and Cu(II) were examined by the composite electrode. The electrode exhibited the lowest limits of detection (LODs) of 0.5 and 0.3 nM for Hg(II) and Cu(II) in simultaneous determination, the highest sensitivities of 64.5 and 65.9 μA/μM, respectively, and the shortest response time. Both Hg(II) and Cu(II) films electroplated on the surface of composite were used to further analyze change of sensitivity and LOD, respectively. The thickness of films influenced the sensitivity and LOD. The proposed electrode was also performed the analysis of soil sample. The analytic method in this study could open up an avenue for the analysis and detection of metal ions, and provide a reference of electrochemical sensor based on metal films.

Development of an immunochromatographic strip and its application in the simultaneous determination of Hg(II), Cd(II) and Pb(II)

Heavy metal contamination in water has attracted great attention worldwide. The development of a simple, inexpensive, mobile, and rapid analytical technique for simultaneous detection of Hg(II), Cd(II) and Pb(II) is still a challenging analytical problem. Here we describe an immunochromatographic strip based on specific monoclonal antibodies (McAbs)-labeled gold nanoparticle for rapid, simultaneous, and specific determination of Hg(II), Cd(II) and Pb(II) in water samples. In the method, Hg(II)-ITCBE-BSA, Cd(II)-ITCBE-BSA, Pb(II)-ITCBE-BSA and goat anti-mouse IgG antibody were coated on the NC membrane as test lines (TLs) and control line (CL), respectively. Anti-Hg(II)-ITCBE McAb-particle, anti-Cd(II)-ITCBE McAb-particle and anti-Pb(II)-ITCBE McAb-particle were applied to the conjugate pad. The flow of the McAb-particle conjugates along the strip resulted in characteristic TL inversely proportional to the concentration of metal ion, enabling visual and simultaneous determination of Hg(II), Cd(II) and Pb(II) in a single strip. The visual limits of detection (LODs) for the simultaneous determination of Hg(II), Cd(II) and Pb(II) were 8nM, 6nM and 6nM, respectively. The assay can be performed within 10min. The novelty of the developed immunochromatographic assay is simultaneous determination of multiple metal ions using a single strip.

Simultaneous determination of Hg(II) and Zn(II) using a GFP inspired chromophore

A dual-function chemosensor for Hg2+ and Zn2+ ions, inspired by the green fluorescent protein (GFP) chromophore, was designed and synthesized, which could specifically recognize Zn2+ through an “OFF–ON” fluorescence mechanism due to the restriction of the free rotation of the aryl–alkene bond, whilst also producing a selective visible colorimetric response from yellow to pink with Hg2+ ions. The response upon exposure to Zn2+ and Hg2+ is instantaneous, and the detect limits of Zn2+ and Hg2+ are 2.18×10−8M and 4.91×10−7M respectively.

Nonextractive Trace Level Simultaneous Determination of Mercury(II) and Zinc(II) in Environmental Samples with 2‐(5‐Bromo‐2‐pyridylazo)‐5‐diethylaminophenol and Cetylpyridinium Chloride

A simple, rapid, selective, and sensitive method for the derivative spectrophotometric determination of Hg(II) and its simultaneous determination in the presence of Zn(II) using 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant, has been developed. The molar absorption coefficient and analytical sensitivity of the 1∶1 Hg(II) complex at 558 nm (λmax) are 5.78×104 L mol−1 cm−1 and 0.67 ng mL−1, respectively. The detection limit of Hg(II) is 1.40×10−2 ng mL−1, and Beer's law is valid in the concentration range 0.05–2.40 µg mL−1. Overlapping spectral profiles of Hg(II) and Zn(II) complexes in zero‐order mode interfere in their simultaneous determination. However, 0.10–2.00 µg mL−1 of Hg(II) and 0.065–0.650 µg mL−1 of Zn(II), when present together, can be simultaneously determined at zero cross point of the derivative spectrum, without any prior separation. The relative standard deviation for six replicate measurements of solutions containing 0.134 µg mL−1 of Hg(II) and 0.620 µg mL−1 of Zn(II) is 1.72 and 1.47%, respectively. The proposed method has successfully been evaluated for trace level simultaneous determination of Hg(II) and Zn(II) in environmental samples.

Simultaneous determination of Hg(II) and alkylated Hg, Pb, and Sn species in human body fluids using SPME-GC/MS-MS

A GC/MS-MS method for the determination of Hg(II) and alkylated Hg, Pb, and Sn species in human urine is described. Separation and identification of the metal species are performed by capillary gas chromatography coupled with an ion-trap mass spectrometer with electron impact ionization in the tandem-MS mode. For sample preparation a very promising technique was applied that is based on a derivatization with sodium tetraethylborate followed by headspace solid phase microextraction (SPME). Operation of the used ion trap in the tandem-MS mode yields in improved detection limits because of a signal-to-noise ratio that is at least one order of magnitude better than in the MS mode. The detection limits in real matrices like urine are between 7 and 22 ng/L for all species investigated. Urinary levels of inorganic Hg in non-occupationally exposed persons with and without dental amalgam were found to be between 0.1 and 1.4 μg/L. A reference material (“ClinRep, Level I”) was used for quality assurance. Compared to the coupling of GC with ICP-MS (“inorganic” MS), the advantage of the proposed method using an “organic” MS is that (i) the species can be directly identified via their precursor and daughter ions and (ii) analysis can be performed with a commercially available hyphenated technique at moderate costs and needs no lab-made interfacing. Moreover, it offers a real multi-element/multi-species capability with low detection limits and a minimum of sample preparation.