Separation of inorganic anions on reversed-phase C18 columns with a phosphomolybdate mobile phase.

Reversed-phase high performance liquid chromatography (RP-HPLC) is the most widely used chromatographic method. In addition to hydrophobic interactions, additional interactions such as electrostatic interactions may participate in the retention behaviour of an analyte. This makes it possible to use RP-HPLC for many types of analyte. We describe a simple method for separating inorganic anions on a C18 column, in which retention of inorganic anions is almost entirely due to electrostatic interactions. This leads to rapid separations as well as higher theoretical plate numbers. We used 2 mM phosphoric acid containing a low concentration of disodium molybdate as the mobile phase, which allows UV detection of non-UV-absorbing anions. With this method, we determined eight inorganic anions including several non-UV-absorbing anions photometrically at 220 nm. The detection limits of the examined eight inorganic anions calculated at a signal-to-noise ratio of 3 were between 0.3 and 10 µM. The detector response was linear over three orders of magnitude of inorganic anion concentration. The proposed RP-HPLC/UV method was successfully applied to determine inorganic anions in some water samples.

The determination of zinc using flow injection and continuous flow analysis combined with a polymer inclusion film-coated column: Application to the determination of zinc in alloys and commercial lithium chloride.

A column coated with a polymer inclusion film (PIF) containing Aliquat 336 as carrier cast on glass beads packed in a glass tube is described for the separation, preconcentration, and determination of zinc(II) in flow injection analysis (FIA) and continuous flow analysis (CFA) systems. In the FIA method, 200 µL of a sample solution containing 2 mol/L lithium chloride is injected into a 2 mol/L lithium chloride stream. This converts zinc(II) ion into its anionic chlorocomplexes which are then extracted into the Aliquat 336-based PIF by anion exchange. The extracted zinc(II) is then back-extracted into a stream of 1 mol/L sodium nitrate solution and determined spectrophotometrically using 4-(2-pyridylazo)resorcinol as the color reagent. The limit of detection (LOD, S/N = 2) was determined as 0.017 mg/L. The usability of the PIF-based FIA method was demonstrated by the determination of zinc in alloys. The PIF-coated column was also employed successfully in the CFA determination of zinc(II) as an impurity in commercial lithium chloride samples. For this, 2 mol/L commercial lithium chloride solution was passed through the column for a predetermined time period followed by stripping in a stream of 1 mol/L sodium nitrate solution.

Automated rapid solid-phase extraction system for separation and preconcentration of trace elements using carboxymethylated polyethyleneimine-type chelating resin.

An automated system for the rapid separation and preconcentration of trace elements was developed. Carboxymethylated polyethyleneimine 600 (CM-PEI600), which is a partially carboxymethylated polyethyleneimine with a molecular weight of 600 Da, was used as a chelating resin to quantitatively recover trace elements under high-flow-rate conditions. For accurately and precisely determining trace elements, even with a rough control of the sample and eluent flow volumes, an internal standardization technique was employed for the solid-phase extraction and separation. A recovery test of the deionized water-based sample solution was conducted using this system, and good results, with a recovery of 92% or higher, were obtained for 11 elements (Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn). Eight elements present in certified groundwater and wastewater reference materials (ES-L-1 and EU-L) were separated and preconcentrated using this system. Almost all the determined values were within their tolerance intervals, and no significant differences were observed between the determined and certified values, demonstrating the validity of this method. The time required for the separation and preconcentration using approximately 100 mL of the sample solution was approximately 6.5 min, and theoretically, the system could be used to preconcentrate 17 samples in an hour because extraction and elution could be conducted simultaneously using two cartridges packed with the chelating resin. Using this system equipped with cartridges packed with CM-PEI600 resin, solid-phase extraction and the separation of multiple elements were performed simultaneously, automatically, and rapidly, enabling the accurate and precise determination of trace elements in environmental water and inorganic salts even by rapidly flowing the sample solutions using peristaltic pumps. Compared to NOBIAS Chelate PA-1, a commercially available chelating resin, the CM-PEI600 resin can recover trace elements even under an extremely high flow rate of approximately 50 mL min-1.

Applicability of Internal Standardization with Yttrium to the Solid-phase Extraction of Trace Elements in Groundwater and Wastewater Using an Aminocarboxylic Acid-type Chelating Resin.

Internal standardization was applied to the solid-phase extraction of trace elements using the following commercially available aminocarboxylic acid-type chelating resins: InertSep ME-2, NOBIAS Chelate PA-1, and Presep PolyChelate. The concentration of the trace elements in initial sample solution can be calculated by using the ratio of the added amount of the internal standard element, Y, in the initial sample solution to that in the final solution after the solid-phase extraction, which is proportional to the volume of the sample solution passed through the cartridge, and the ratio of the volume of the initial sample solution to that of a blank solution for preparing the calibration curve. In this solid-phase extraction, strict control of the volumes of the sample solution passed through the cartridge and the final solution after the solid-phase extraction is not needed because these are not used in the calculation of the trace element concentration. The solid-phase extraction with the internal standardization using Y could be applied to the separation and preconcentration of some trace elements, namely Cd, Co, Cu, Fe, Ni, Pb, Ti, and Zn in an artificial seawater spiked with the elements and some certified reference materials, EnviroMAT ES-L-1 Ground Water and EU-L-3 Waste Water, without any interference.

Size resolved characteristics of urban and suburban bacterial bioaerosols in Japan as assessed by 16S rRNA amplicon sequencing.

To study the size-resolved characteristics of airborne bacterial community composition, diversity, and abundance, outdoor aerosol samples were analysed by 16S rRNA gene-targeted quantitative PCR and amplicon sequencing with Illumina MiSeq. The samples were collected using size-resolved samplers between August and October 2016, at a suburban site in Toyama City and an urban site in Yokohama City, Japan. The bacterial communities were found to be dominated by Actinobacteria, Firmicutes, and Proteobacteria. At the genus level, we found a high abundance of human skin-associated bacteria, such as Propionibacterium, Staphylococcus, and Corynebacterium, in the urban site. Whereas, a high abundance of bacteria associated with soil and plants, such as Methylobacterium and Sphingomonas, was observed in the suburban site. Furthermore, our data revealed a shift in the bacterial community structure, diversity, and abundance of total bacteria at a threshold of 1.1-µm diameter. Interestingly, we observed that Legionella spp., the causal agents of legionellosis in humans, were mainly detected in > 2.1 µm coarse particles. Our data indicate that local environmental factors including built environments could influence the outdoor airborne bacterial community at each site. These results provide a basis for understanding the size-resolved properties of bacterial community composition, diversity, and abundance in outdoor aerosol samples and their potential influence on human health.

Potential of Carboxymethylated Polyallylamine as a Functional Group on Chelating Resin for Solid-Phase Extraction of Trace Elements.

New chelating resins immobilizing carboxymethylated polyallylamine (CM-PAA) were prepared by immobilizing PAAs with some molecular weights on methacrylate resins and then carboxymethylating a part of amino groups in the PAAs using various amounts of sodium monochloroacetate. The molecular weight of PAA barely affected both the amount of PAA immobilized on the resin and the relationship between the carboxymethylation (CM) rate and the ratio of the amount of monochloroacetate used in the CM step. The selectivity of CM-PAA resin for solid-phase extraction of trace elements was almost the same as that of a resin immobilizing carboxylymethylated polyethyleneimine; 10 elements, namely Cd, Co, Cu, Fe, Mo, Ni, Pb, Ti, V, and Zn, could be quantitatively recovered over a wide pH range and alkali and alkaline earth elements were scarcely extracted under acidic and neutral conditions. The CM-PAA resin was applicable to the separation and preconcentration of the elements in a certified reference material (Waste Water, EU-L-1) and a real environmental water sample (ground water).

Thermal Decomposition Behavior of a Chelating Resin Immobilizing Carboxymethylated Polyethyleneimine: Possibility of Estimation of Carboxymethylation Rate.

Chelating resins immobilizing carboxymethylated polyethyleneimine (CM-PEI) with different carboxymethylation rates were prepared. The thermal decomposition behavior of CM-PEI resins was investigated using thermogravimetry-differential thermal analysis/photo ionization-quadrupole mass spectrometry (TG-DTA/PI-QMS) and ion attachment ionization-quadrupole mass spectrometry equipped with direct inlet probe (DIP/IA-QMS). The obtained results suggested that the carboxymethyl group decomposed at relatively low temperature (150 °C - 300 °C); the peak areas at m/z 45 and 59 in TG-DTA/PI-QMS and m/z 58, 70, and 72 in DIP/IA-QMS significantly increased with increasing carboxymethylation rate. These relationships should be useful for estimating the carboxymethylation rate of CM-PEI resin.

Phosphomethylated Polyethyleneimine-immobilized Chelating Resin: Role of Phosphomethylation Rate on Solid-Phase Extraction of Trace Elements.

Chelating resins immobilizing phosphomethylated polyethyleneimine (PM-PEI) with different phosphomethylation (PM) rates were prepared by using different amounts of both phosphonic acid and paraformaldehyde in the phosphomethylation of PEI immobilized on a methacrylate resin as a base resin. The extraction of many elements improved with increasing PM rate; REEs, Be, Fe, Mo, Ti, and V were quantitatively extracted at pH 2. The elution of the elements tended to become difficult with increasing PM rate. When a PM-PEI resin with a PM rate of 0.26 was used, REEs and Be could be eluted using 0.2 mol L-1 EDTA solution adjusted to a pH of 7 and 3 mol L-1 nitric acid, respectively, although the elution of Fe, Mo, Ti, and V was insufficient. The PM-PEI resin could be reused at least 10 times to recover REEs and Be without the influence of any other elements. The PM-PEI resin could be applied to a recovery test using artificial seawater spiked with REEs, except for Sc, Tm, Yb, and Lu, and the separation of the REEs in NIST SRM 1515 Apple Leaves.

A porous sintered material consisting of Presep PolyChelate as a chelating resin and particulate polyethylene as a thermoplastic binder for solid-phase extraction of trace elements.

Cylinder-type and disk-type sintered materials consisting of Presep PolyChelate, which is a commercially available chelating resin immobilizing carboxymethylated polyethyleneimine as a functional group, and particulate polyethylene as a thermoplastic binder were prepared using a polymer sintering technique. The sintered materials had a continuously porous structure. The sintering process at 130 °C for 20 min did not affect the ability of the chelating resin in the sintered materials; the selectivity of the sintered material was almost the same as that of the particulate chelating resin which was not sintered. The sintering materials could quantitatively extract 11 kinds of trace elements, namely Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn, at pH 5.5. When the disk-type sintered material was used, the recoveries of these elements remained almost constant at a flow rate of at least 50 mL min-1; the extracted elements could be eluted using 10 mL of 3 mol L-1 nitric acid at a flow rate of 5 mL min-1. Solid-phase extraction using the disk-type sintered material was applied to the separation and preconcentration of trace elements prior to their inductively coupled plasma atomic emission spectrometric determination. The method was applicable to analyses of certified reference materials (EnviroMAT ES-L-1 ground water and EU-L-3 waste water) and a commercially available table salt.

Improvement of Chromium(VI) Extraction from Acidic Solutions Using a Poly(vinyl chloride)-based Polymer Inclusion Membrane with Aliquat 336 as the Carrier.

An important reason for the inefficient extraction of Cr(VI) from its acidic solutions into polymer inclusion membranes (PIMs), consisting of poly(vinyl chloride) as the base-polymer and Aliquat 336 as the carrier, was found to be associated with the leaching of Aliquat 336 from the PIMs into the solutions, where it subsequently reduced the anionic Cr(VI) species to cationic Cr(III) species. The PIM extraction efficiency for Cr(VI) was significantly improved by the addition of NaNO3 to the solutions, which suppressed the leaching of Aliquat 336 and the reduction of Cr(VI) to Cr(III).

Diffusion-Controlled Recrystallization of Water Sorbed into Poly(meth)acrylates Revealed by Variable-Temperature Mid-Infrared Spectroscopy and Molecular Dynamics Simulation.

Recrystallization behaviors of water sorbed into four poly(meth)acrylates, poly(2-methoxyethyl acrylate), poly(tetrahydrofurfuryl acrylate), poly(methyl acrylate), and poly(methyl methacrylate), are investigated by variable-temperature mid-infrared (VT-MIR) spectroscopy and molecular dynamics (MD) simulation. VT-MIR spectra demonstrate that recrystallization temperatures of water sorbed into the polymers are positively correlated with their glass-transition temperatures reported previously. The present MD simulation shows that a lower-limit temperature of the diffusion for the sorbed water and the glass-transition temperatures of the polymers also have a positive correlation, indicating that the recrystallization is controlled by diffusion mechanism rather than reorientation mechanism. Detailed molecular processes of not only recrystallization during rewarming but also crystallization during cooling and hydrogen-bonding states of water in the polymers are systematically analyzed and discussed.

Chelating resin immobilizing carboxymethylated polyethyleneimine for selective solid-phase extraction of trace elements: Effect of the molecular weight of polyethyleneimine and its carboxymethylation rate.

The effect of the molecular weight of polyethyleneimine (PEI), defined as a compound having two or more ethyleneamine units, and of its carboxymethylation rate (CM/N), represented by the ratio of ion-exchange capacity to the amount of N on the resin, on the selective solid-phase extraction ability of the chelating resin immobilizing carboxymethylated (CM) PEI was investigated. The chelating resins (24 types) were prepared by immobilization of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, PEI300 (MW=ca. 300), and PEI600 (MW=ca. 600) on methacrylate resins, followed by carboxymethylation with various amounts of sodium monochloroacetate. When resins with approximately the same CM/N ratio (0.242-0.271) were used, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, Zn, and alkaline earth elements increased with increasing the molecular weight of PEIs under acidic and weakly acidic conditions; however, the extraction behavior of Mo and V was only slightly affected. This was probably due to the increase in N content of the resin, resulting in an increase in carboxylic acid groups; the difference in the molecular weight of PEIs immobilized on the resin exerts an insignificant influence on the selective extraction ability. The CM/N ratio considerably affected the extraction behavior for various elements. Under acidic and neutral conditions, the recovery of Cd, Co, Cu, Fe, Ni, Pb, Ti, and Zn increased with increasing CM/N values. However, under these conditions, the recovery of alkaline earth elements was considerably low when a resin with low CM/N ratio was used. This is presumably attributed to the different stability constants of the complexes of these elements with aminocarboxylic acids and amines, and to the electrostatic repulsion between the elements and the protonated amino groups in the CM-PEI. The recovery of Mo and V decreased or varied with increasing CM/N values, suggesting that the extraction of these elements occurred mainly by the anion-exchange reaction. For the separation and preconcentration of trace elements in samples containing large amounts of alkali and alkaline earth elements, the CM-PEI600 resin with CM/N=0.131 (Cu(II) extraction capacity, 0.37mmol g(-)(1)) was found to be the most suitable because it scarcely extracts alkali and alkaline earth elements under acidic and neutral conditions. This resin proved to be convenient for separating and preconcentrating Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in the certified reference materials (EnviroMAT EU-L-1 wastewater and ES-L-1 ground water) and commercially available table salt.

Mid-infrared spectroscopic investigation of the perfect vitrification of poly(ethylene glycol) aqueous solutions.

Crystallization/recrystallization behaviors of poly(ethylene glycol) (PEG) aqueous solutions with water contents (WC's) of ∼36-51 wt % were investigated by temperature-variable mid-infrared spectroscopy. At a WC of 43.2 wt %, crystallization and recrystallization of water and PEG were not observed. At this specific WC value (WCPV), perfect vitrification occurred. Below and above the WCPV value, crystallization/recrystallization behaviors changed drastically. The crystallization temperature below WCPV (237 K) was ∼10 K greater than that above WCPV (226 K). Recrystallization above and below WCPV occurred in one (213 K) and two (198 and 210 K) steps, respectively. These findings resulted from the difference in the (re)crystallization behaviors of water molecules associated with PEG chains with helical and random-coil conformations. These two types of water molecules might have limiting concentrations for their (re)crystallization, indicating that perfect vitrification might have occurred when the concentrations of the two types of water molecules were less than the limiting concentrations of their (re)crystallization.

The use of a polymer inclusion membrane as a sorbent for online preconcentration in the flow injection determination of thiocyanate impurity in ammonium sulfate fertilizer.

A polymer inclusion membrane (PIM) is used for the first time as a sorbent in the construction of a preconcentration column to enhance the sensitivity in flow injection analysis (FIA). The PIM-coated column is readily prepared by coating the PIM containing poly(vinyl chloride), Aliquat 336, and 1-tetradecanol onto glass beads packed in a glass tube. The determination of trace amounts of thiocyanate in ammonium sulfate fertilizer demonstrates the potential of the proposed PIM-coated column in FIA. Thiocyanate standards or samples of relatively large volume (e.g. up to 2000 µL) are injected into a nitrate carrier stream. The sample zone passes through the proposed preconcentration column where thiocyanate is concentrated in a smaller volume of a carrier solution thus resulting in up to 7.4 fold increase in sensitivity. Thiocyanate is detected spectrophotometrically after its reaction with Fe(III) downstream of the preconcentration column. The limits of detection of thiocyanate in the absence and presence of 20 g L(-1) ammonium sulfate (S/N=2) are 0.014 and 0.024 mg L(-1), respectively. Thiocyanate was successfully determined in several samples of ammonium sulfate fertilizer.

Chelating materials immobilizing carboxymethylated pentaethylenehexamine and polyethyleneimine as ligands.

This article presents an overview of our recent progress on the development of chelating materials. Carboxymethylated pentaethylenehexamine (CM-PEHA) and polyethyleneimine (CM-PEI) as chelating ligands show excellent performance for the solid-phase extraction of trace elements. Chelating resins immobilizing these ligands can be readily prepared by immobilizing PEHA and PEI on methacrylate resins and then carboxymethylating them. Chelating fiber can also be prepared with a wet spinning technique using a mixture of a viscose solution and a solution containing fine particulate CM-PEHA resin or CM-PEI. The potentials of these chelating materials for the separation and preconcentration of trace elements are outlined.

Potential of Presep(®) PolyChelate as a chelating resin: comparative study with some aminocarboxylic acid-type resins.

The potential of Presep(®) PolyChelate as a chelating resin was studied in detail. The chelating resin with extraction capacity for Cu of 0.30 mmol L(-1) could quantitatively extract Cd, Co, Cu, Fe, Mo, Ni, Pb, V, and Zn at pH 4 or 5.5; however, only very scant amounts of Na, K, Mg, and Ca were captured at pH levels below 7. The quantitative extraction could be achieved in 100 - 1000 mL of artificial seawater and at a flow rate of 3 - 30 mL min(-1). The performance of Presep(®) PolyChelate was compared to the other aminocarboxylic acid-type chelating resins, including Nobias Chelate-PA1, Chelex 100, Muromac B-1, Lewatit TP 207, and NTA Superflow, under the same conditions. The solid-phase extraction of the nine elements in the certified reference material (ES-L-1, ground water) and a commercially available table salt was also demonstrated.

Molecular properties and extracellular processing of the lipase of Staphylococcus warneri M.

Staphylococcus warneri M exhibited extracellular lipase activity. By zymogram analysis of extracellular proteins, multiple bands were detected and the profiles changed depending on the bacterial growth phase. N-terminal amino acid sequences of three bands (N1-N3) were determined. From the genome library of S. warneri M whole DNA, the gene-directing lipase activity (named gehC(WM)) was cloned and characterized. The gehC(WM )gene encoded a protein (GehC(WM)), whose calculated molecular mass was 83.4 kDa, and the sequence was similar to the other staphylococcal lipases. Though two lipases have been known from S. warneri 863, GehC(WM) differs from both of them, indicating that this enzyme is the third extracellular lipase of the S. warneri strain. The N-terminal sequences of the N1-N3 polypeptides completely coincided with the deduced amino acid sequences in GehC(WM). GehC(WM) was predicted to be a prepro-protein. In vitro processing and protein sequencing suggested that pro-GehC(WM) is possibly processed by extracellular glutamyl endopeptidase, PROM. Inductively coupled plasma-atomic emission spectrometer analysis showed that purified his-tagged mature GehC(WM) possessed zinc ion. A gehC(WM) knockout mutant was constructed by insertion of an erythromycin resistance gene into the gehC(WM). Zymogram and immunoblot analyses of the gehC(WM )mutant indicated that GehC(WM) was a major extracellular lipase of S. warneri M.

Chelating fibers prepared with a wet spinning technique using a mixture of a viscose solution and a polymer ligand for the separation of metal ions in an aqueous solution.

Chelating fibers containing polymer ligands such as carboxymethylated polyallylamine, carboxymethylated polyethyleneimine, and a copolymer of diallylamine hydrochloride/maleic acid were prepared with a wet spinning technique using mixtures of a viscose solution and the polymer ligands. The chelating fibers obtained effectively adsorbed various metal ions, including Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), Ti(IV), and Zn(II). The metal ions adsorbed could be readily desorbed using 0.1 or 0.5 mol L(-1) HNO(3). The chelating fiber containing carboxymethylated polyallylamine was available for the separation of some metal ions in synthetic wastewater containing a large amount of Na(2)SO(4). The wet spinning technique using a solution containing a base polymer and a polymer ligand was quite simple and effective and would be applicable for preparing various chelating fibers.

Solid-phase extraction of cobalt(II) from lithium chloride solutions using a poly(vinyl chloride)-based polymer inclusion membrane with Aliquat 336 as the carrier.

The extraction of cobalt(II) from solutions containing various concentrations of lithium chloride, hydrochloric acid, and mixtures of lithium chloride plus hydrochloric acid is reported using a poly(vinyl chloride) (PVC)-based polymer inclusion membrane (PIM) containing 40% (w/w) Aliquat 336 as a carrier. The extraction from lithium chloride solutions and mixtures with hydrochloric acid is shown to be more effective than extraction from hydrochloric acid solutions alone. The solution concentrations giving the highest amounts of extraction are 7 mol L(-1) for lithium chloride and 8 mol L(-1) lithium chloride plus 1 mol L(-1) hydrochloric acid for mixed solutions. Cobalt(II) is easily stripped from the membrane using deionized water. The cobalt(II) species extracted into the membrane are CoCl(4)(2-) for lithium chloride solutions and HCoCl(4)(-) for mixed solutions; these form ion-pairs with Aliquat 336. It is also shown that both lithium chloride and hydrochloric acid are extracted by the PIM and suppress the extraction of cobalt(II) by forming ion-pairs in the membrane (i.e. R(3)MeN(+)·HCl(2)(-) for hydrochloric acid and R(3)MeN(+)·LiCl(2)(-) for lithium chloride).

Determination of cadmium in water samples by liquid electrode plasma atomic emission spectrometry after solid phase extraction using a mini cartridge packed with chelate resin immobilizing carboxymethylated pentaethylenehexamine.

Solid phase extraction using a mini cartridge packed with 22 mg of chelate resin immobilizing carboxymethylated pentaethylenehexamine was successfully utilized for separation/preconcentration of cadmium in water samples prior to liquid electrode plasma atomic emission spectrometric (LEP-AES) determination. The combined method with the extraction and LEP-AES was applicable to the determination of cadmium in the certified reference materials (EU-L-1 wastewater and ES-L-1 groundwater); the detection limit was 0.20 microg in 200 mL of sample solution (500-fold preconcentration).