Tomonari Umemura

Multielement determination of trace metals in seawater by ICP-MS with aid of down-sized chelating resin-packed minicolumn for preconcentration.

The multielement determination of trace metals in seawater was carried out by inductively coupled plasma mass spectrometry (ICP-MS) with aid of a down-sized chelating resin-packed minicolumn for preconcentration. The down-sized chelating resin-packed minicolumn was constructed with two syringe filters (DISMIC 13HP and Millex-LH) and an iminodiacetate chelating resin (Chelex 100, 200-400mesh), with which trace metals in 50mL of original seawater sample were concentrated into 0.50mL of 2M nitric acid, and then 100-fold preconcentration of trace metals was achieved. Then, 0.50mL analysis solution was subjected to the multielement determination by ICP-MS equipped with a MicroMist nebulizer for micro-sampling introduction. The preconcentration and elution parameters such as the sample-loading flow rate, the amount of 1M ammonium acetate for elimination of matrix elements, and the amount of 2M nitric acid for eluting trace metals were optimized to obtain good recoveries and analytical detection limits for trace metals. The analytical results for V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb, and U in three kinds of seawater certified reference materials (CRMs; CASS-3, NASS-4, and NASS-5) agreed well with their certified values. The observed values of rare earth elements (REEs) in the above seawater CRMs were also consistent with the reference values. Therefore, the compiled reference values for the concentrations of REEs in CASS-3, NASS-4, and NASS-5 were proposed based on the observed values and reference data for REEs in these CRMs.

Determination of REEs in seawater by ICP-MS after on-line preconcentration using a syringe-driven chelating column

A syringe-driven chelating column (SDCC) was applied to develop an on-line preconcentration/inductively coupled plasma mass spectrometry (ICP-MS) method for preconcentration and determination of rare earth elements (REEs) in seawater samples. The present on-line preconcentration system consists of only one pump, two valves, an SDCC, an ICP-MS, several connectors, and Teflon tubes. Optimizations of adsorption pH condition, sample loading flow rate, and integration range were carried out to achieve optimum measurement conditions for REEs in seawater sample. Six minutes was enough for a preconcentration and measurement cycle using 10 mL of seawater sample, where the detection limits for different REEs were in the range of 0.005 pg mL(-1) to 0.09 pg mL(-1). Analytical results of REEs in a seawater certified reference material (CRM), NASS-5, confirmed the usefulness of the present method. Furthermore, concentrations of REEs in Nikkawa Beach coastal seawater were determined and discussed with shale normalized REE distribution pattern.

Chemical anchoring of lauryl methacrylate-based reversed phase monolith to 1/16″ o.d. polyetheretherketone tubing

In this paper, we describe a method for the preparation of easy-to-use reversed-phase monolithic microbore columns. Polyetheretherketone (PEEK) tubing with an outer diameter of 1/16″ and an inner diameter of 1.0 mm was used as a column housing (empty column), and in it lauryl methacrylate (LMA) was copolymerized with ethylene dimethacrylate (EDMA). In order to chemically anchor the polymer monolith to the tube wall, the inner wall surface was pretreated by the following two-step procedure. (1) 50% sulfuric acid was filled into the PEEK tubing and left to stand for 6 h to generate sulfonate groups on the surface. (2) After washing with Milli-Q water, the sulfonated PEEK surface was brought into contact with 1 M glycidyl methacrylate in dichloromethane (or acetone) at 40°C for 4 h to introduce methacryloyl groups via the reaction of sulfonate groups and epoxy groups. Mechanical strength and column efficiency of the resulting monoliths were evaluated through the separation of a series of alkylbenzenes in acetonitrile-water (50:50, v/v) eluent over the flow rate range of 50-750 μL/min (corresponding to 1.7-25.5 mm/s). The poly(LMA-co-EDMA) monolith provided acceptable column efficiency of 2000 theoretical plates/10 cm (HETP value of 50 μm) for amylbenzene (separation factor k=40) and low flow resistance of 0.5 MPa/10 cm at a normal flow rate of 50 μL/min. The methacryloylated PEEK tubing tightly held the monolith, and the monolithic column exhibited good pressure resistance up to 15 MPa, allowing rapid separation at a 15-20 fold higher flow rate than normal.

Direct injection determination of theophylline and caffeine in blood serum by high-performance liquid chromatography using an ODS column coated with a zwitterionic bile acid derivative.

An ODS column dynamically coated with zwitterionic bile acid derivative, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS), was evaluated for direct injection determination of drugs in blood serum by HPLC. Polar functional groups such as sulfonate, ammonium and the three hydroxyl groups in CHAPS protruding towards an aqueous mobile phase formed a hydrophilic layer over the ODS reversed-phase surface, which resulted in high molecular mass compounds such as proteins being prevented from penetrating into the internal hydrophobic region. The bulk of the proteins were eluted as an unretained or nearly unretained band by using 0.2 mM sodium hydrogenphosphate solution (pH 7.4) as the mobile phase. In contrast, small molecules such as some inorganic anions and aromatic compounds were retained and thereby separated from one another. It was confirmed that the ODS column modified with CHAPS acts as a restricted access-type column with a hydrophobic interior and a hydrophilic exterior. Hence biological fluids could be directly injected into the CHAPS-coated ODS column. The present HPLC system using the CHAPS-coated ODS column was applied to the determination of theophylline and caffeine in human blood serum. The detection limits for the two drugs with UV absorption at 273 nm were 0.2 and 0.5 mg l-1 (injection volume 20 microliters) and the relative standard deviations of peak area measurements were < 1.4% and 2.2%, respectively, for 10 replicate measurements of serum spiked with 5 mg l-1 of each of the drugs.

A simple combination of higher-oxidation-state FeX3 and phosphine or amine ligand for living radical polymerization of styrene, methacrylate, and acrylate

Higher-oxidation-state iron halides [FeX3 (X = Cl, Br)] were employed in conjunction with a series of ligands, mainly monodentate phosphines and amines, to effect the living radical polymerization of various vinyl monomers such as styrene, methyl methacrylate (MMA), and methyl acrylate (MA). Almost all combinations examined could enable polymerizations in the absence of exogenous reducing agents. However, appropriate combinations of FeX3 and ligands gave rise to polymers in a living manner, with controlled molecular weights and narrow molecular weight distributions (Mw/Mn = 1.1–1.2). Ligand combinations included FeCl3 with PnBu3, PtBu3, or NnBu3 (for styrene); FeCl3 with PtBu3 or NnBu3 (for MMA); and FeBr3 with PPh3 (for MA). Model reactions and spectroscopic analysis suggest that FeCl3 most likely disproportionates into the Fe(III)Cl4− anion and Fe(III)Cl2+ cation in the presence of Lewis base ligands (PR3 and NR3). The latter cationic species, coordinated with the ligand [Fe(III)Cl2(PR3)+ or Fe(II)Cl2(PR3)˙+], acts as the active catalyst. Assistance from the electron-rich ligand allows the catalyst to induce metal-catalyzed living radical polymerization. The Fe(III)-based catalyst could also be easily and almost quantitatively removed from the polymer product simply by washing with aqueous acid to minimize the amount of iron contamination (<5 ppm).

Multicolor Polymer-Dispersed Liquid Crystal

The widespread utilization of personal-use multimedia has triggered a vigorous expansion in the manufacturing of cheap, simple and power-saving displays. Because the most widely used liquid crystal (LC) displays are composed of many different sets of optical elements – such as color fi lters, polarising plates, and alignment fi lms – the simplifi cation of such designs will potentially lead to decreases in the cost of manufacturing and better power-saving capabilities. A display with a polymer-dispersed liquid crystal (PDLC) fi lm is one of the simplest models possible because it has no polarising plate or alignment fi lm. [ 1–6 ] Although this display is structurally simplifi ed and very bright, there is still room for improvement due to the use of a color fi lter. Displays consisting of stimuli-sensitive multichromic materials are among the leading candidates for such ideal simple systems. [ 7 , 8 ]

Seasonal change in the level and the chemical forms of aluminum in soil solution under a Japanese cedar forest

The level of dissolved aluminum and its chemical forms in soil solutions consecutively collected by a porous cup vacuum sampler were monitored over a period from January 2001 to December 2001 at a Japanese cedar (Cryptomeria japonica) forestry area susceptible to acid deposition to characterize current soil dynamics and to evaluate potential tree damages. Distinction and characterization of Al species with differential toxicities were performed by two complementary speciation techniques; cation-exchange HPLC with fluorometric detection using 8-hydroxyquinoline-5-sulfonic acid (HQS) and size-fractionation/inductively coupled plasma atomic emission spectrometry (ICP-AES). The concentrations of free Al (mainly Al3+ and Al(OH)2+) and inert Al (existing as the complexed and/or colloidal forms) ranged between 0-150 microM and 10-50 microM, respectively. The concentrations of inert Al were mostly below 40 microM during an annual cycle and showed no marked seasonal variation, while free Al concentrations showed a clear tendency to increase in the spring and summer seasons (in the period from April to August) probably due to the enhanced activity of microbial nitrification and the resultant soil acidification. Major cations and anions were also regularly determined and their seasonal changes were correlated with that of the dissolved Al concentration. Correlations between total Al (mainly existing as free Al) and the related species (and environmental conditions) were as follows: Al and Mg (R=0.96, P<0.01), Al and Ca (R=0.97, P<0.01), Al and NO3- (R=0.68, P<0.01), Al and temperature (R=0.68, P<0.01), Al and solution pH (R=-0.61, P<0.01), solution pH and NO3- (R=-0.65, P<0.01).

Adsorption of Methylene Blue onto Silylated Silica Surfaces, Studied Using Visible Attenuated Total Reflection Spectroscopy with a Slab Optical Waveguide

The behavior of methylene blue (MB) molecules at silica/water and silylated silica/water interfaces was examined using visible attenuated total reflection spectroscopy with a slab optical waveguide (SOWG). An alkyl silane coating changed the adsorbed form of MB on the surface from a dimer (λmax = 600 nm, bare silica surface) to a monomer (λmax = 670 nm), and the carbon number of the silylation reagent influenced the amount of adsorption and the orientation of the molecule. Moreover, the addition of an anionic surfactant, dodecylbenzenesulfonate (DBS), caused the deposition of MB/DBS ion pairs, which gave an identical attenuated total reflection (ATR) spectrum to that of the dimer. Linear dichroism measurements revealed that the ion pairs were adsorbed onto the silylated silica surface randomly in terms of the orientation angle of MB, while the MB monomer was strongly oriented, i.e., the direction of the transition moment of MB roughly parallels the surface plane. This difference in the orientation angles of the adsorbed species can be utilized for their selective detection using polarization SOWG measurements.

Metallomics study on all-elements analysis of salmon egg cells and fractionation analysis of metals in cell cytoplasm

Salmon egg cells were the subject of investigation for all-elements analysis in a single biological cell, where the elements in egg cells were simultaneously determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted acid digestion. As a result, 74 elements among 78 stable isotope elements were determined or detected, although H, C, N, and O were determined separately by conventional CHN elemental analysis. In addition, the survey of protein-binding metallic elements as well as metalloid elements in salmon egg cell cytoplasm was performed by the fractionation analysis with a hyphenated system of high-performance liquid chromatography (HPLC)/ICP-MS using a 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate (CHAPS)-coated octadecylsilyl silica (ODS) column and a size exclusion chromatography (SEC) column.

Evaluation of sulfobetaine-type zwitterionic stationary phases for ion Chromatographic separation using water as a mobile phase

Abstract Ion Chromatographic separation of inorganic ions (anions and cations) was investigated by using three kinds of sulfobetaine-type surfactants (CHAPS, C12SB, and C14SB) as the stationary phases, which were coated by hydrophobic adsorption on the ODS column. In the present separation system, pure water was used as a mobile phase. Since the amount of surfactant adsorbed on the ODS surface significantly influenced the retention behaviors of inorganic ions, the amounts of the sulfobetaine-type surfactants adsorbed were estimated by the breakthrough procedure. The maximum amounts of CHAPS, C12SB and C14SB adsorbed were 0.40, 0.87 and 1.08 mmol, respectively. It was elucidated from the chromatograms of inorganic ions that the retention behavior of inorganic anions was directly related to the surface charges arising from the adsorbed surfactants. The large surface charge was effective for the efficient separation of inorganic ions in water elution. In addition, their retention behavior was strongly affected by the hydrophobicity of the adsorbed surfactants as well as the ionic functional groups of the surfactants which produced the charged surface. The elution order of inorganic anions was correlated with the Hofmeister series. This suggests that the hydration energies of the ions play important roles in separation in the water elution system.