Just Published: Microchemical Journal

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Microchemical Journal
http://rss.sciencedirect.com/publication/science/6599

Selected papers from the latest issue:

Bioaccumulation of trace elements in water, sediment, and six fish species from a freshwater wetland, Iran

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
A. Hosseini Alhashemi, M.S. Sekhavatjou, B. Hassanzadeh Kiabi, A.R. Karbassi
The distributions of Cd, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in water, sediment, and six fish species (Barbus grypus, Barbus luteus, Barbus sharpeyi, Cyprinus carpio, Liza abu, and Silurius trisostegus) in the most important and largest wetland in southwest, Iran were determined. The concentrations of vanadium (0.10–0.37mgL⁻¹) and lead (0.63–0.12mgL⁻¹) in water and manganese (153.1–420.1mgkg⁻¹), and nickel (17.8–79.21mgkg⁻¹) in sediment were high among other elements. Accumulation of trace elements in muscle of studied fishes was related to Zn (28.57–49.50mgkg⁻¹), Mn (1.03–24.80mgkg⁻¹), V (4.87–6.75mgkg⁻¹), Pb (2.90–6.39mgkg⁻¹), Cu (3.21–5.00mgkg⁻¹), Ni (0.96–2.63mgkg⁻¹), Cr (0.7–2.60mgkg⁻¹), Co (0.41–1.26mgkg⁻¹) and Cd (0.13–0.41mgkg⁻¹). Also, concentration levels of all studied elements in whole body of L. abu were the highest. The potential uptake of toxic elements including Cd, Cr, Co, Ni and Pb in muscle of studied fish species decreases as B. luteus > C. carpio > B. sharpeyi > B. luteus.

Highlights

► Heavy metals in sediment decreases as Mn>Ni>Zn>V>Cu>Pb>Cr>Co>Cd. ► Accumulation of elements in carnivore specimen was lower than omnivore species. ► All fish species showed high effective ingested dose over the EPA guideline.

Dielectric barrier discharge micro-plasma emission source for the determination of thimerosal in vaccines by photochemical vapor generation

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Haiyang He, Zhenli Zhu, Hongtao Zheng, Qing Xiao, Lanlan Jin, Shenghong Hu
A fast, simple and green approach to direct determinate thimerosal in vaccines by photochemical vapor generation (PVG) coupled to optical emission spectrometry (OES) using dielectric barrier discharge (DBD) as excitation/emission source was described in this paper. With the exception of dilution and formic acid addition, the sample was not subjected to other treatment. This method eliminated the need for using strong oxidizing conditions and conventional chemical reducing agents. In addition, the DBD micro-plasma emission source was operated with low power (≤18W) and low gas consumption (120mLmin⁻¹). A sample throughput of 30h⁻¹ was obtained with the proposed flow injection-PVG-DBD-OES. The main operation parameters and the potential interferences affecting the determination were investigated. The detection limits for Hg²⁺ and thimerosal (as Hg) were calculated to be 0.19μgL⁻¹ and 0.17μgL⁻¹. Repeatability, expressed as the relative standard deviation of the spectral peak height, was 0.99% (n=11) and 1.9% (n=11) for 20μgL⁻¹ Hg²⁺ and thimerosal standard, respectively. The proposed method was successfully applied to the analysis of commercial vaccines. All these results demonstrated that PVG-DBD-OES could provide a green way for the rapid detection of thimerosal in vaccines.

Highlights

► PVG provides good compatibility with DBD micro-plasma. ► No sample pretreatment is essential for thimerosal determination. ► Greatly reduced the use of chemical reagents, enhanced the “green” character. ► DBD sustained at low power and gas consumption, miniaturized the entire system.

Arsenic determination in complex mining residues by ICP OES after ultrasonic extraction

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Jéssica F.R. Paula, Roberta E.S. Froes-Silva, Virgínia S.T. Ciminelli
The impact caused by mining residue deposits with high amounts of arsenic is a potential environmental problem and motive for investigations. Arsenic is always associated with gold ores and is present in mining areas, probably due to sulfide oxidation and the high pH range where arsenic is soluble. It has been shown that some samples of residues coming from the studied deposits presented arsenic concentrations above 2500mg kg⁻¹. The aim of this work is to develop methods for arsenic extraction in mining residues employing ultrasound assistance extraction and analyte determination by hydride generation ICP OES. The analytical method provided analysis precision and a better evaluation of environmental impact of mining residue deposits. Optimal conditions for ultrasound assisted extraction were obtained by evaluation of parameters such as the position of the sample flask inside the ultrasound bath and temperature as a function of the immersion time. These tests identified the ideal position of the sample flask and indicated that the maximum time that the sample could be analyzed without arsenic lost due to increase of the temperature was 180minutes. With these conditions, an experimental design was developed to obtain the optimal conditions of arsenic extraction, evaluating the type of extraction solution and the sonication time. A 2² Central Composite Design (CCD) was employed to evaluate the acid concentration (HCl, HNO3 and H3PO4) and the sonication time (maximum 180minutes). The quadratic equation of response surface generated by CCD, employing HNO3, indicated that the best condition for arsenic extraction is using an acid concentration of 2.7molL⁻¹ and sonication for 136minutes to give an average concentration of 1847±17mgkg⁻¹. Recovery studies were carried out and the obtained values were close to 100%. Optimal conditions of arsenic extraction were obtained by evaluating the operational parameters of ultrasound bath and the analysis conditions with the experimental design. The method developed contributes significantly to a more precise evaluation of the real environmental impact caused by the mining residues deposit.

Highlights

► The use of ultrasound bath for arsenic extraction can be used without analyte loss until 180minutes of sonication. ► Operational conditions established for arsenic extraction were acid concentration (HNO3) of 2.7molL⁻¹ and sonicating for 136minutes. ► Application and recovery studies with real samples close to 100% of extraction.

Investigation of Cd contents in several phosphate rocks used for the production of fertilizer

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Swe Swe Mar, Masanori Okazaki
Phosphate rocks (PRs) can be a source of cadmium pollution in soil and food chain. PRs are mainly used for the manufacturing of phosphate fertilizers. The characteristics of PRs with special reference to cadmium, which are important phosphate fertilizer source, were investigated. In my field of study, PR of USA (PR1: from Wyoming, PR2: from Florida PR3: from Idaho), Morocco (PR4: from Qued Zem), Russia (PR5 from Slyudanka), and Japan (PR6: from Okinawa) were selected and compared using X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray diffraction (XRD). Elemental analysis results of PR samples showed that they were mainly composed of Ca, P, Si, Al, S and Fe. Total phosphate concentration in all PRs was 6 to 38% on the average. The Cd concentration levels in all PR samples ranged from 0.15 to 507mgkg⁻¹. PR4 sample exhibited about two times higher Cd concentration than those of the literatures so far published. XRD analysis revealed that; fluorapatite ((Ca5(PO4)3)F), hydroxyapatite (Ca10(PO4)6(OH)2) and carbonate fluorapatite (Ca5(PO4,CO3)3F) were the dominant minerals. This study also confirmed that PR3 and PR4 exhibited higher Cd content and prominent mineral component was carbonate fluorapatite, suggesting that Cd might be exchanged to Ca and/or occluded in carbonate fluorapatite during its formation by sedimentation.

Highlights

► Investigation of PR on Cd conc. was needed to consider phosphate fertilizer source. ► Cd conc. in several PRs was compared under this study and other studies. ► PR4 exhibited the highest Cd conc. than those of the literature so far published. ► Main peak mineral of PR samples was found to be F, HA and CFA. ► Higher Cd content and prominent mineral of CFA in PR3 and PR4 were demonstrated.

Indirect cloud point extraction and spectrophotometric determination of nitrite in water and meat products

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Nahid Pourreza, Mohammad Reza Fat'hi, Ali Hatami
A new indirect micelle mediated cloud point extraction method has been developed for sensitive determination of trace amounts of nitrite by spectrophotometry. The method is based on the well known oxidation–reduction reaction of nitrite by iodide ion in acidic medium and cloud point extraction of I3 ⁻ formed from aqueous solution using Triton X-100. The extracted surfactant rich phase is diluted with water and its absorbance is measured at 365nm. The effects of different operating parameters such as concentration of surfactant, KI concentration, temperature, incubation time and acid concentration on the cloud point extraction were studied in details and a set of optimum conditions was obtained. A linear calibration graph was obtained in the range of 8–120ngmL⁻¹. The limit of detection (LOD) based on three times the standard deviation of the blank (3Sb) was 6.0ngmL⁻¹ (n=10) and the relative standard deviation (RSD) for determination of 60ngmL⁻¹ of nitrite was 3.40% (n=10). The method was applied to the determination of nitrite in meat products and water samples.

Highlights

► A new indirect micelle mediated cloud point extraction method for nitrite. ► The method uses the well known oxidation–reduction reaction of nitrite by iodide to form I3 ⁻. ► The method was applied to determine nitrite in water samples and meat product. ► The procedure is eco-friendly.

Headspace solid-phase microextraction for the determination of volatile sulfur compounds in odorous hyper-eutrophic freshwater lakes using gas chromatography with flame photometric detection

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Xin Lu, Chengxin Fan, Jingge Shang, Jiancai Deng, Hongbin Yin
A simple and efficient method based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography coupled to flame photometric detection was developed for the simultaneous determination of five volatile sulfur compounds (VSCs; hydrogen sulfide (H2S), methanethiol (MeSH), dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS)) in hyper-eutrophic freshwater lakes suffering from black water agglomerate. Carboxen/polydimethylsiloxane (CAR/PDMS) fiber was selected for the extraction of VSCs, and various parameters, such as the stirring rate, sample volume, ionic strength, duration and temperature of extraction and the duration and temperature of desorption, were optimized for extraction efficiency. The linearity spanned approximately three orders of magnitude for all of the studied compounds. The method detection limits (MDLs) and method quantification limits (MQLs) ranged from 1.6 to 93.5ngL⁻¹ and 10 to 500ngL⁻¹, respectively, depending on the analyzed compound. The reproducibility of the method was between 3.7 and 11.9%, and the recovery was approximately 100%. The developed analytical method was successfully applied to the determination of VSCs in odorous freshwater lakes, and the concentrations of the five target compounds were detected in the 0.33 to 166.60μgL⁻¹ range.

Highlights

► Optimized HS-SPME by GC-FPD for routine determination of fives VSCs in lake waters. ► VOSCs and the inorganic species H2S were simultaneously determined. ► Parameters that may affect to the determination were systematically optimized. ► The detection of VSCs was linear over three orders of magnitude for target compounds. ► The method was applied to analysis of odorous water samples from the Lake Taihu. (China).

Ultrasensitive determination of cobalt and nickel by atomic fluorescence spectrometry using APDC enhanced chemical vapor generation

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Chujie Zeng, Yunzhen Jia, Yong-Ill Lee, Xiandeng Hou, Li Wu
Ammonium pyrrolidine dithiocarbamate (APDC) was used to enhance the chemical vapor generation (CVG) efficiency of nickel and cobalt. Volatile nickel and cobalt species were effectively generated through reduction of acidified analyte solution with 2% potassium tetrahydroborate (KBH4) solution in the presence of 0.02% (m/v) APDC. Thus, a new CVG-atomic fluorescence spectrometric (AFS) method was developed for determination of ultratrace nickel and cobalt. Influencing parameters were evaluated in detail, including the complexing reagents, the concentrations of APDC, nitric acid and KBH4, flow rates of carrier gas and shield gas, lengths of the reaction tube and the transfer tube, as well as interferences. Under the optimized conditions, the limits of detection (LOD) were 1ngmL⁻¹ and 6ngmL⁻¹ for nickel and cobalt, respectively. The calibration curves were linear in the range of 10 to 300ngmL⁻¹ and 50 to 1200ngmL⁻¹ for nickel and cobalt, respectively. The potential application of this method was validated by the accurate determination of nickel in three certified reference materials. It was also applied to determination of cobalt in water samples and Vitamin B12 with good recoveries of spiked samples.

Highlights

► APDC could remarkably improve the chemical vapor generation efficiency of nickel and cobalt. ► A new method was established for determination of ultratrace nickel and cobalt by AFS. ► The method was sucessfully used in real sample analysis for nickel and cobalt.

Spectroscopic visualization of CH in methane/hydrogen plasmas for synthesis of carbonaceous materials and surface micromorphology

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Qingchun Shen, Yasushi Miyata, Shigeaki Morita, Kuniyuki Kitagawa
Plasma-enhanced chemical vapor deposition (PECVD) is among the promising processes to synthesize advanced materials. Carbon films of sp² with different micro-structures (wall-like/pole-like) are attractive for battery electrodes and have been synthesized from different methane+hydrogen plasmas. To clarify the interaction between plasma and a substrate target surface, an attempt to visualize the intermediate species CH was made in this work. Visible spectra (VIS-spectra) of the spontaneous optical emission from the plasmas were recorded by a multi-channel spectrometer to elucidate reaction mechanisms during the deposition process. The overall spectroscopic emission intensity from the methane-lean plasma was much higher than that from the methane-rich plasma. However, the emission intensity of CH radical in the methane-rich plasma was slightly higher than that in the methane lean one. In addition, two-dimensional spectroscopic images of CH radicals generated in the plasmas were captured using a CCD camera fitted with an optical band-pass filter at 430nm. It was found that the negative bias voltage was responsible for a turbostratic in the deposited films.

Highlights

► CH radical visualizations showed intuitive spontaneous emission intensity changes according to the different plasma conditions. ► The negative bias voltage is responsible for the turbostratic structure on the surfaces of the substrates. ► Aggregation structures of the synthesized carbonaceous films varied from the density of CH radicals in the plasma gases.

Application of flow field-flow fractionation (FlFFF) for size characterization of carbon black particles in ink

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Jingi Bae, Woonjung Kim, Kyunil Rah, Euo Chang Jung, Seungho Lee
The size and distribution of the carbon black particles play important roles with respect to application in diverse areas. When used in inks, the smaller the particle size, the better the carbon black particles are dispersed, and thus the glossiness of ink increases. Asymmetrical flow field-flow fractionation (AsFlFFF) has shown to be applicable for size characterization of various types of colloidal particles. In the present study, AsFlFFF was employed to analyze the size of carbon black particles used in ink. Carbon black suspensions were prepared by dispersing carbon black powder in aqueous media containing various types of copolymeric dispersing agents of hydrophobic (styrene) and hydrophilic (acrylic or maleic acid) monomers. Experimental parameters of AsFlFFF including the type of the surfactant added to the carrier liquid, the channel and the cross flow rates, and the ionic strength were varied to find an optimum condition for analysis of the carbon black particles. It was found that the use of FL-70 as an additive to the carrier liquid resulted in the best elution profile among the tested surfactants (cationic, anionic, and nonionic surfactant). Although the mean sizes obtained by AsFlFFF and dynamic light scattering (DLS) were generally in good agreements, DLS failed to distinguish between the carbon black suspensions having different size distributions, whereas AsFlFFF was able to differentiate easily. Results indicated that the carbon black particles were dispersed better with the copolymeric dispersing agents having the hydrophobic content of 2 to 3 times higher than the hydrophilic molecules. At the styrene:acrylic acid of 1:1, the carbon black particles tend to have larger mean sizes and the size distributions tend to become broader, probably due to poor dispersion. Furthermore, it was observed that as the mean size of the carbon black particles decreased and the size distribution became narrower, the ink became clearer and glossier.

Highlights

► Flow FFF was employed to analyze carbon black particles. ► Use of FL-70 as an additive to the carrier liquid resulted in the best elution profile. ► Carbon black was dispersed well with dispersants having hydrophobic content of 2-3 times higher than hydrophilic content. ► As the carbon black particle size decreased, the ink became clearer and glossier.

A new pretreatment and improved method for determination of selected estrogens in high matrix solid sewage samples by liquid chromatography mass spectrometry

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Qingcai Chen, Jianghong Shi, Wei Wu, Xiaowei Liu, Hui Zhang
This article describes a pretreatment procedure for samples that possess high matrix interferences to better analyze four estrogens including estrone (E1), 17β-estradiol (E2), estriol (E3) and 17α-ethinyl estradiol (EE2) and xenoestrogens bisphenol A (BPA) in solid samples, including the activated sludge and sediment samples investigated here. During the pretreatment procedure, the target compounds were extracted from the samples using accelerated solvent extraction (ASE), and the extracted samples were then purified using four steps for clean-up: liquid–liquid extraction (LLE), Florisil clean-up, aqueous alkali extraction (AAE) and hydrophilic–lipophilic balance (HLB) enrichment. The absolute recoveries of the activated sludge and sediment were 88–97% and 75–100%, respectively, and the limits of detection were both below 0.1ngg⁻¹. After the activated sludge and sediment samples were purified using the four clean-up steps, their matrix interference effects decreased to 0.5–32% and −3.2–0.8%, respectively, and their absorbance values were also clearly reduced. However, the activated sludge and sediment samples that were extracted by ASE but were not purified through the above-mentioned four steps resulted in matrix interference effects on the four estrogens and BPA that reached 81–233% and 47–95%, respectively, in which E3 and BPA were completely suppressed in the activated sludge samples.

Highlights

► This analytical method is applied for trace estrogens under a complex matrix. ► Good purification results are ensured by a precisely designed procedure. ► The purification effects were evaluated by UV–vis and matrix effect equation. ► Both recovery and optimization experiments were conducted for each procedure. ► Factors which influence the recovery were discussed in a mechanism level.

Histidine functionalized multi-walled carbon nanotubes as sorbent for flow injection-electrothermal atomic absorption spectrometric ultrasensitive determination of trace vanadium (V) in biological and environmental samples

06 June 2012, 09:03:53

Publication year: 2012
Source:Microchemical Journal, Volume 104
Yue Liu, Yan Li, Lin Yang
Histidine functionalized multi-walled carbon nanotubes (MWCNTs-His) were synthesized for selective preconcentration of V(V). Using flow injection coupled with electrothermal atomic absorption spectrometric strategy, an on-line ultrasensitive determination of V(V) in biological and environmental samples was achieved. Statical and dynamical adsorption of V(V) with MWCNTs-His was carefully evaluated. Isotherm and kinetics of adsorption were studied and fitted in the Langmuir model. The MWCNTs-His sorbent was demonstrated to be good column packings for on-line preconcentration. All of the experimental conditions with MWCNT-His packed microcolumn for the preconcentration and determination of V(V) were investigated in detail. Including the optimal sample's pH, sample's flow rate, loading time, eluting solution and interfering ions were performed on-line, to ensure automatic determination with a high precision. With a consumption of 5.0mL sample solution and a preconcentration time of 1min, an enhancement factor of 35 with a detection limit (3s) of 9ngL⁻¹ or 0.2nM is achieved. The sample throughput and the precision (RSD) for 11 replicate measurements of 400ngL⁻¹ level was 28h⁻¹ and 1.5%, respectively. The method was applied to the determination of trace V(V) in a variety of biological and environmental samples.

Highlights

► MWCNTs-His have been employed as sorbents for detection of trace V(V). ► MWCNTs-His was proved to be good column packings after preconcentration of V(V) statically and dynamically evaluated. ► The detection limit (3 s) of developed method achieved 9ngL⁻¹ or 0.2nM. ► The developed method was applied to determination of trace V(V) in a variety of biological and environmental samples.