Humic acid (HA) coated Fe 3 O 4 nanoparticles (Fe 3 O 4 /HA) were developed for the removal of toxic Hg(II), Pb(II), Cd(II), and Cu(II) from water. Fe 3 O 4 /HA were prepared by a coprecipitation procedure with cheap and environmentally friendly iron salts and HA. TOC and XPS analysis showed the as-prepared Fe 3 O 4 / HA contains ∼11% (w/w) of HA which are fractions abundant in O and N-based functional groups. TEM images and laser particle size analysis revealed the Fe 3 O 4 /HA (with ∼10 nm Fe 3 O 4 cores) aggregated in aqueous suspensions to form aggregates with an average hydrodynamic size of ∼140 nm. With a saturation magnetization of 79.6 emu/g, the Fe 3 O 4 /HA can be simply recovered from water with magnetic separations at low magnetic field gradients within a few minutes. Sorption of the heavy metals to Fe 3 O 4 /HA reached equilibrium in less than 15 min, and agreed well to the Langmuir adsorption model with maximum adsorption capacities from 46.3 to 97.7 mg/g. The Fe 3 O 4 /HA was stable in tap water, natural waters, and acidic/ basic solutions ranging from 0.1 M HCl to 2 M NaOH with low leaching of Fe (e3.7%) and HA (e5.3%). The Fe 3 O 4 /HA was able to remove over 99% of Hg(II) and Pb(II) and over 95% of Cu(II) and Cd(II) in natural and tap water at optimized pH. Leaching back of the Fe 3 O 4 /HA sorbed heavy metals in water was found to be negligible.

Metal-engineered nanoparticles (MENPs) with unique optical, electronic, and chemical properties have potential applications in catalysis, optical devices, and electronic applications. Particularly, metallic silver nanoparticles (AgNPs) have been applied as a broadspectrum antimicrobial agent in recent years. Colloidal nanosilver has been used for more than 100 years and has been registered as a biocidal material in the U.S. since 1954.2 AgNPs are the most common materials in nanotechnology-based consumer products, and the worldwide production of AgNPs was estimated at 500 t/a in 2008. 3 Inevitably, these MENPs can be discharged into the environment through the manufacturing, usage, disposal, and recycling processes of commercial products. 4À7The potential toxicity 8 and bioaccumula-

Room-temperature ionic liquids (ILs) are gaining wide recognition as novel solvents in chemistry. Their application in analytical chemistry, especially in separating analytes, is merited because ILs have some unique properties, such as negligible vapor pressure, good thermal stability, tunable viscosity and miscibility with water and organic solvents, as well as good extractability for various organic compounds and metal ions. This review gives a brief overview of the application of ILs in analytical chemistry, including sample preparation, chromatographic/capillary electrophoretic (CE) separation, and detection. ª

can be formed and survive for a longer extraction time; therefore, a much higher enrichment factor for PAHs can be reached. For low-volatility PAHs, direct-immersion LPME provides higher enrichment factors than that of headspace LPME. However, the enrichment factor obtained by headspace LPME was almost 3-fold of that by direct-immersion LPME in a 30-min extraction of the most volatile PAH, naphthalene. For 30-min directionimmersion LPME of EPA priority PAHs, the enrichment factor, correlation coefficient (R 2 ), and reproducibility (RSD, n ) 5) were in the range of 42-166, 0.9169-0.9976, and 2.8-12%, respectively. Considering that IL can be easily prepared from relatively inexpensive materials and tuned by combination of different anions and cations for task-specific extraction of analytes from various solvent media, this proposed method should have great potentiality in sample preparation. Furthermore, the nonvolatility of IL makes it potentially useful for headspace LPME of volatile analytes.Ionic liquids (IL) are ionic media resulting from combinations of organic cations and various anions. They may be liquids at room temperature. Their use as novel solvent systems for organic synthesis and catalysis has received a good deal of attention. 1 IL have several unique properties that make them useful in a variety of chemical processes. For example, they have no effective vapor pressure, the viscosity and the miscibility in water and other organic solvents can be tuned by changing the combination of different anions and cations of IL, and the preparation is easy from relatively inexpensive materials. 1,2 As a result of these properties, IL is emerging as an alternative recyclable medium for separation. Recently, IL were considered as attractive water-immiscible phases in liquid-liquid extraction. 3-5 IL were also used in organic solvent-supercritical CO 2 biphasic extractions 6-8 and in pervaporation. 4,9 By using two typical IL, 1-butyl-3-methylimidazolium hexafluorophosphate G.

Twelve elements (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, Cd and Pb) in 24 sediment samples at eight sites (S1 -S8) from the East China Sea were analyzed with the BCR sequential extraction (SE) protocol to obtain the metal distribution patterns in this region. The results showed that the heavy metal pollutions in S4 and S8 were more severe than in other sampling sites, especially Cd and Pb pollution. In the top sediments at S4 and S8, both the total contents and the most dangerous non-residual fractions of Cd and Pb were extremely high. More than 90% of the total concentrations of V, Cr, Mo and Sn existed in the residual fraction. Fe, Co, Ni, Cu and Zn mainly (more than 60%) occurred in the residual fraction. While Mn, Pb and Cd dominantly presented in the non-residual fractions in the top sediments. The metal distribution patterns with depth and the correlations between total organic carbon (TOC) and the total Fe -Mn content were also investigated. The results showed that, for most of the elements except Fe, the concentration of elements in fraction A in the top sediments was higher than that in other depth. The similar rule was also found in fraction B but not in fraction C. Besides, the distributions of V, Cd in fraction B and Pb, Cd, Cu in fraction C might be affected by TOC. D

Silver nanoparticles (AgNPs) were selectively concentrated from environmental water samples without disturbing their sizes and shapes by cloud point extraction (CPE) with Triton X-114 (TX-114). The highest extraction efficiency for AgNPs was obtained at about their zero point charge pH (pH PZC ), which was ∼3.0-3.5 for the studied AgNPs. Addition of salts such as 35 mM NaNO 3 or 10 mM Na 2 S 2 O 3 enhanced the phase separation and thus increased the extraction efficiency of AgNPs. Furthermore, Na 2 S 2 O 3 efficiently eliminated the interference of Ag + due to the formation of a complex between Ag + and S 2 O 3 2-that was not extracted into the TX-114-rich phase. The presence of humic acid at an environmentally relevant level (0-30 mg/L dissolved organic carbon) had no effect on the extraction of AgNPs. An enrichment factor of 100 was obtained with 0.2% (w/v) TX-114, and the recoveries of AgNPs from various environmental samples were in the range of 57-116% at 0.1-146 µg/L spiked levels. The AgNPs preconcentrated into the TX-114-rich phase were identified by transmission electron microscopy/scanning electron microscopy-energy dispersive spectrometer/UV-vis spectrum and quantified after microwave digestion by inductively coupled plasma mass spectrometry with a detection limit of 0.006 µg/L (34.3 fmol/L particles of AgNPs). As the proposed CPE procedure preserves the sizes and shapes of AgNPs, the original morphology of AgNPs in environmental waters can be obtained by characterizing the preconcentrated analytes in the TX-114-rich phase. This proposed method provides an efficient approach for the analysis and tracking of AgNPs in the environment.Given their large quantity of production and widespread applications, engineered nanomaterials (NMs) will inevitably be released into the environment during production, handling, and disposal. The unique properties of NMs, such as high surfaceto-volume ratio, mobility and catalytic activity, could cause adverse effects on the eco-environmental system. Evaluation of the risk of NMs to human health and the environment relies on the understanding of their fate, transport, and exposure, as well as their effects on the fate, transport, and exposure of other toxic substances. However, little is known about the occurrence, fate, and toxicity of NMs, partly due to the lack of quantitative methodology for NMs in environmental and biological matrixes. 1-6A variety of methods have been developed for characterization and quantitative analysis of NMs in simple matrixes, as well as natural NMs in a complex matrix such as environmental waters and soils. [7][8][9][10][11][12] Characterization was mainly conducted with microscopy and microscopy-related techniques (e.g., scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM)), whereas quantification was mainly based on the coupling of size separation techniques (e.g., size-exclusion chromatography, 13-15 field flow fractionation, [16][17][18] hydrodynamic chromatography, 19,20 and capill...

The adsorptive potential of multiwalled carbon nanotubes (MWNTs) for solid-phase extraction of bisphenol A, 4-nnonylphenol, and 4-tert-octylphenol was investigated for the first time. The three analytes are quantitatively adsorbed on a MWNTs-packed cartridge, then the analytes retained on the cartridge are quantitatively desorbed with suitable amounts of methanol. Finally, the analytes in the methanol eluate are determined by high performance liquid chromatography-fluorometric detection. Parameters influencing the extraction efficiency, such as volume of the sample solutions, pH of the sample, and the eluent volume, were examined. Comparative studies showed that MWNTs were superior to C 18 for the extraction of the more polar analyte bisphenol A and at least as effective as C 18 for the extraction of 4-n-nonylphenol and 4-tert-octylphenol. Compared to XAD-2 copolymer, MWNTs exhibited a better property for the extraction of all three analytes. The developed method has been applied to determine bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol in several environmental water samples. The accuracy of the proposed method was tested by recovery measurements on spiked samples, and good recovery results (89.8-104.2%) were obtained. Detection limits of 0.083, 0.024, and 0.018 ng mL -1 for bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol, respectively, were achieved under the optimized conditions.

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