Man He

Dithizone modified magnetic nanoparticles for fast and selective solid phase extraction of trace elements in environmental and biological samples prior to their determination by ICP-OES.

A fast and simple method for analysis of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II) in environmental and biological samples was developed by combining magnetic solid phase extraction (MSPE) with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection. Dithizone modified silica-coated magnetic Fe(3)O(4) nanoparticles (H(2)Dz-SCMNPs) were prepared and used for MSPE of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II). The prepared magnetic nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The factors affecting the extraction of the target metal ions such as pH, sample volume, eluent, and interfering ions had been investigated and the adsorption mechanism of the target metals on the self-prepared H(2)Dz-SCMNPs was investigated by FT-IR and X-ray photo electron spectroscopy (XPS). Under the optimized conditions, the detection limits of the developed method for Cr(III), Cu(II), Pb(II) and Zn(II) were 35, 11, 62, and 8ngL(-1), respectively, with the enrichment factor of 100. The relative standard deviations (RSDs, c=10μgL(-1), n=7) were in the range of 1.7-3.1% and the linear range was 0.1-100μgL(-1). The proposed method had been validated by two certified reference materials (GSBZ50009-88 environmental water and GBW07601 human hair), and the determined values were in good agreement with the certified values. The method was also applied for the determination of trace metals in real water and human hair samples with recoveries in the range of 85-110% for the spiked samples. The developed MSPE-ICP-OES method has the advantages of simplicity, rapidity, selectivity, high extraction efficiency and is suitable for the analysis of samples with large volume and complex matrix.

Chromium(III)-imprinted silica gel for speciation analysis of chromium in environmental water samples with ICP-MS detection

A new chromium(III)-imprinted 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS)-functionalized silica gel sorbent was synthesized by a surface imprinting technique and was employed as a selective solid-phase extraction material for speciation analysis of chromium in environmental water samples prior to its determination by inductively coupled plasma mass spectrometry (ICP-MS). The prepared Cr(III)-imprinted silica gel shows the selectivity coefficient of more than 700 for Cr(III) in the presence of Mn(II). The static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Cr(III) were 30.5 mg g(-1) and 13.4 mg g(-1). It was also found that Cr(VI) could be adsorbed at low pH by the prepared imprinted silica gel, and this finding makes it feasible to enrich and determine Cr(VI) at low pH without adding reducing reagents. The imprinted silica gel sorbent offered a fast kinetics for the adsorption and desorption of both chromium species. Under the optimized conditions, the detection limits of 4.43 pg mL(-1) and 8.30 pg mL(-1) with the relative standard deviations (R.S.D.s) of 4.44% and 4.41% (C=0.5 ng mL(-1), n=7) for Cr(III) and Cr(VI) were obtained, respectively. The proposed method was successfully applied to the speciation of trace chromium in environmental water samples. To validate the proposed method, two certified reference materials were analyzed and the determined values were in a good agreement with the certified values. The developed method is rapid, selective, sensitive and applicable for the speciation of trace chromium in environmental water samples.

Graphene oxide–silica composite coating hollow fiber solid phase microextraction online coupled with inductively coupled plasma mass spectrometry for the determination of trace heavy metals in environmental water samples

In this work, a novel graphene oxide-silica (GO-silica) composite coating was prepared for hollow fiber solid phase microextraction (HF-SPME) of trace Mn, Co, Ni, Cu, Cd and Pb followed by on-line inductively coupled plasma mass spectrometry (ICP-MS) detection. The structure of the prepared graphene oxide and GO-silica composite was studied and elucidated by atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The GO-silica composite coated hollow fiber was characterized by scanning electron microscope (SEM), and the results show that the GO-silica composite coating possessed a homogeneous and wrinkled structure. Various experimental parameters affecting the extraction of the target metal ions by GO-silica composite coated HF-SPME have been investigated carefully. Under the optimum conditions, the limits of detection (LODs, 3σ) for Mn, Co, Ni, Cu, Cd and Pb were 7.5, 0.39, 20, 23, 6.7 and 28 ng L(-1) and the relative standard deviations (RSDs, c(Mn, Co, Cd)=0.05 μg L(-1), c(Ni, Cu, Pb)=0.2 μg L(-1), n=7) were 7.2, 7.0, 5.6, 7.3, 7.8 and 4.6%, respectively. The accuracy of the proposed method was validated by the analysis of Certified Reference Material of GSBZ 50009-88 environmental water and the determined values were in a good agreement with the certified values. The proposed method has been successfully applied for the determination of trace metals in real environmental water samples with recoveries ranging from 85 to 119%.

Simultaneous speciation analysis of inorganic arsenic, chromium and selenium in environmental waters by 3-(2-aminoethylamino) propyltrimethoxysilane modified multi-wall carbon nanotubes packed microcolumn solid phase extraction and ICP-MS

Speciation analysis of inorganic arsenic, chromium and selenium in environmental waters is of great significance for the monitoring of environmental pollution. In this work, 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS) functionalized multi-wall carbon nanotubes (MWCNTs) were synthesized and employed as the adsorbent for simultaneous speciation analysis of inorganic arsenic, chromium and selenium in environmental waters by microcolumn solid-phase extraction (SPE)-inductively coupled plasma mass spectrometry (ICP-MS). It was found that As(V), Cr(VI) and Se(VI) could be selectively adsorbed on the microcolumn packed with AAPTS-MWCNTs adsorbent at pH around 2.2, while As(III), Cr(III) and Se(IV) could not be retained at this pH and passed through the microcolumn directly. Total inorganic arsenic, chromium and selenium was determined after the oxidation of As(III), Cr(III) and Se(IV) to As(V), Cr(VI) and Se(VI) with 10.0 μmol L(-1) KMnO4. The assay of As(III), Cr(III) and Se(IV) was based on subtracting As(V), Cr(VI) and Se(VI) from the total As, Cr and Se, respectively. Under the optimized conditions, the detection limits of 15, 38 and 16 ng L(-1) with the relative standard deviations (RSDs) of 7.4, 2.4 and 6.2% (c=1 µg L(-1), n=7) were obtained for As(V), Cr(VI) and Se(VI), respectively. The developed method was validated by analyzing four Certified Reference Materials, rainwater, Yangtze River and East Lake waters.

On-line separation and preconcentration of inorganic arsenic and selenium species in natural water samples with CTAB-modified alkyl silica microcolumn and determination by inductively coupled plasma-optical emission spectrometry

A new, simple, and selective method has been presented for the separation and preconcentration of inorganic arsenic (As(III)/As(V)) and selenium (Se(IV)/Se(VI)) species by a microcolumn on-line coupled with inductively coupled plasma-optical emission spectrometry (ICP-OES). Trace amounts of As(V) and Se(VI) species were separated and preconcentrated from total As and Se at desired pH values by a conical microcolumn packed with cetyltrimethylammonium bromide (CTAB)-modified alkyl silica sorbent in the absence of chelating reagent. The species adsorbed by CTAB-modified alkyl silica sorbent were quantitatively desorbed with 0.10 ml of 1.0 mol l(-1) HNO(3). Total inorganic arsenic and selenium were similarly extracted after oxidation of As(III) and Se(IV) to As(V) and Se(VI) with KMnO(4) (50.0 micromol l(-1)). The assay of As(III) and Se(IV) were based on subtracting As(V) and Se(VI) from total As and total Se, respectively. All parameters affecting the separation/preconcentration of As(V) and Se(VI) including pH, sample flow rate and volume, eluent solution and volume have been studied. With a sample volume of 3.0 ml, the sample throughput was 24h(-1) and the enrichment factors for As(V) and Se(VI) were 26.7 and 27.6, respectively. The limits of detection (LODs) were 0.15 microg l(-1) for As(V) and 0.10 microg l(-1) for Se(VI). The relative standard deviations (RSDs) for nine replicate determinations at 5.0 microg l(-1) level of As(V) and Se(VI) were 4.0% and 3.6%, respectively. The calibration graphs of the method for As(V) and Se(VI) were linear in the range of 0.5-1000.0 microg l(-1) with a correlation coefficient of 0.9936 and 0.9992, respectively. The developed method was successfully applied to the speciation analysis of inorganic arsenic and selenium in natural water samples with satisfactory results.

Separation and preconcentration of inorganic arsenic species in natural water samples with 3-(2-aminoethylamino) propyltrimethoxysilane modified ordered mesoporous silica micro-column and their determination by inductively coupled plasma optical emission spectrometry.

A simple and sensitive method using micro-column packed with 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS) modified ordered mesoporous silica combined with inductively coupled plasma optical emission spectrometry (ICP-OES) for the speciation of inorganic arsenic (As(III) and As(V)) has been developed. The adsorption behaviors of As(III) and As(V) on AAPTS modified ordered mesoporous silica were investigated. It was found that As(V) can be selectively adsorbed on the micro-column within pH of 3-9, while As(III) could not be retained in the studied pH range and passed through the micro-column directly. Total inorganic arsenic was extracted after the oxidation of As(III) to As(V) with 50.0 micromol L(-1) KMnO(4). The assay of As(III) was based on subtracting As(V) from total As. The effect of various parameters on the separation/preconcentration of As(III) and As(V) have been investigated and the optimal experimental conditions were established. The adsorption capacity of AAPTS modified ordered mesoporous silica for As(V) was found to be 10.3 mg g(-1). The detection limit of the method for As(V) was 0.05 microg L(-1) with an enrichment factor of 100, and the relative standard deviation (R.S.D.) was 5.7% (n=7, C=1.0 microg L(-1)). In order to validate the developed method, a certified reference material GSBZ50004-88 environmental water sample was analyzed and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the speciation analysis of inorganic arsenic in natural water samples.

Speciation of butyltin compounds in environmental and biological samples using headspace single drop microextraction coupled with gas chromatography-inductively coupled plasma mass spectrometry

A method based on headspace single drop microextraction (HS-SDME) in combination with gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) was proposed for the speciation analysis of butyltin compounds in environmental and biological samples. The sodium tetraethylborate (NaBEt4) and sodium tetrahydroborate (NaBH4) were used as the derivatizing reagent for in situ derivatization of the butyltins. For the two derivatizations, the HS-SDME parameters such as organic solvent, drop volume, sample pH, stirring rate, temperature, extraction time and the ionic strength were examined systematically. The analytical performance including the linearity ranges, limits of detection (LODs) and reproducibilities of the two derivatizations were compared under the respective optimized conditions. Derivatization with NaBEt(4) proved to be more sensitive and robust than that with NaBH4, leading to the LODs of 1.4 ng/L for MBT, 1.8 ng/L for DBT and 0.8 ng/L for TBT. The reproducibilities, expressed as relative standard deviations (RSDs), were in the range of 1.1-5.3% (c=1 microg/L, n=3). With tripropyltin (TPrT) as internal standard, HS-SDME-GC-ICP-MS with NaBEt(4) derivatization was applied for the speciation analysis of butyltins in real seawater and shellfish samples. The butyltins found in the real-world samples are 31ng/L MBT, 79 ng/L DBT and 32 ng/L TBT for seawater, and 11.6-30.4 ng/g MBT, 11.8-8.9 ng/g DBT and 12.8-52.6 ng/g TBT for different shellfish samples. For validation, the developed method was also employed for the speciation analysis of butyltins in certified reference material (CRM) of PACS-2 sediment, and the determined values are in a good agreement with the certified values. The developed method is simple, rapid, sensitive, and cost-effective and provides an attractive alternative for butyltins speciation in biological and environmental samples with complex matrix.

Polydimethylsiloxane/metal-organic frameworks coated stir bar sorptive extraction coupled to high performance liquid chromatography-ultraviolet detector for the determination of estrogens in environmental water samples

In this work, three kinds of metal-organic frameworks (MOFs), MOF-5, MOF-199 and IRMOF-3, were introduced in stir bar sorptive extraction (SBSE) and novel polydimethylsiloxane (PDMS)/MOFs (including PDMS/MOF-5, PDMS/MOF-199 and PDMS/IRMOF-3) coated stir bars were prepared by sol-gel technique. These PDMS/MOFs coatings were characterized and critically compared for the extraction of seven target estrogens (17-β-estradiol, dienestrol, diethylstilbestrol, estrone, 4-t-octylphenol, bisphenol-A and 17α-ethynylestradiol) by SBSE, and the results showed that PDMS/IRMOF-3 exhibited highest extraction efficiency. Based on the above facts, a novel method of PDMS/IRMOF-3 coating SBSE-high performance liquid chromatography ultraviolet (HPLC-UV) detection was developed for the determination of seven target estrogens in environmental waters. Several parameters affecting extraction of seven target estrogens by SBSE (PDMS/IRMOF-3) including extraction time, stirring rate, pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.15-0.35 μg/L. The linear range was 2-2,500 μg/L for 17α-ethynylestradiol and 1-2,500 μg/L for other estrogens. The relative standard deviations (RSDs) were in the range of 3.7-9.9% (n=8, c=20 μg/L) and the enrichment factors were from 30.3 to 55.6-fold (theoretical enrichment factor was 100-fold). The proposed method was successfully applied to the analysis of estrogens in environmental water samples, and quantitative recoveries were obtained for the spiking experiments.

Nanometer-sized materials for solid-phase extraction of trace elements

AbstractThis review presents a comprehensive update on the state-of-the-art of nanometer-sized materials in solid-phase extraction (SPE) of trace elements followed by atomic-spectrometry detection. Zero-dimensional nanomaterials (fullerene), one-dimensional nanomaterials (carbon nanotubes, inorganic nanotubes, and nanowires), two-dimensional nanomaterials (nanofibers), and three-dimensional nanomaterials (nanoparticles, mesoporous nanoparticles, magnetic nanoparticles, and dendrimers) for SPE are discussed, with their application for trace-element analysis and their speciation in different matrices. A variety of other novel SPE sorbents, including restricted-access sorbents, ion-imprinted polymers, and metal–organic frameworks, are also discussed, although their applications in trace-element analysis are relatively scarce so far. Graphical AbstractNanometer-sized materials for solid-phaseextraction of trace elements and their species

Cellular uptake, elimination and toxicity of CdSe/ZnS quantum dots in HepG2 cells.

In this work, the cellular uptake, elimination and toxicity of CdSe/ZnS QDs in HepG2 cells were comprehensively studied using inductively coupled plasma mass spectrometry (ICP-MS), MTT assay, AO/EB staining, and glutathione level and gene expression analysis. ICP-MS analytical results showed that the uptake efficiency of CdSe QDs by HepG2 cells was lower than that of Cd(II) and Se(IV), and the uptake was dose- and time-dependent. The uptake amount was related to the physicochemical properties of QDs, and NH2-QDs with smaller size were more easily taken up by cells. In combination with various biochemical methodologies, a systematic and thorough quantitative analysis of the in vitro effects of CdSe/ZnS QDs with different coatings was conducted, along with that of Cd (II) and Se (IV). Although Cd(II) above 8.9 μM exhibited obvious toxicity to the cells, no obvious toxicity of four CdSe/ZnS QDs was observed within the tested concentration range (10-100 nM), most likely due to the protection of the ZnS shell and the PEG coating. From the molecular levels point of view, QDs at concentration of 100 nM exhibit obvious impact on the cells, such as increased gene expression (MT1A and CYP1A1), which was positively correlated with the intracellular concentration of QDs.