Determination of ultra-trace Te species in open ocean waters based on Mg(OH)2 coprecipitation, anion exchange resin column separation and inductively coupled plasma sector-field mass spectrometry using a 125Te-enriched isotope spike.

We present a method for the determination of ultra-trace Te species (Te(IV) and Te(VI)) in open ocean waters. The proposed method is based on Mg(OH)2 coprecipitation, anion exchange resin column separation and inductively coupled plasma sector-field mass spectrometry (ICPSFMS) using a 125Te-enriched isotope spike. The largest advantage of the method is that the use of the spike allows accurate and precise determination when it combines with either isotope dilution or recovery correction. Tellurium-IV and VI are preconcentrated in a Mg(OH)2 precipitate and separated mutually by an anion exchange resin column. Te(IV) is retained to the column, while Te(VI) passing through the column is recovered by a subsequent column procedure after reduction of Te(VI) to Te(IV). Te(IV) is successfully eluted with a small amount of 0.01 M HCl. The additional merit of using this eluent is elimination of components that result in a memory effect during the measurement of Te(IV). Possible mass spectral interference on Te(IV) can be excluded by adjusting the mass window, and the Te(IV) concentrations determined by this approach agree well with those independently obtained by an oxidation procedure which removes the interference. The accuracy of the proposed method is verified with homemade standard seawater for which the measured concentrations agree well with results calculated from the value of the standard solution. Procedural blanks for Te(IV) and Te(VI) are 1.5 ± 0.9 pg kg-1 (n = 11) and 1.3 ± 0.9 pg kg-1 (n = 11) with corresponding overall detection limits of 3.0 pg kg-1 and 2.8 pg kg-1, respectively. Using the method, we have clarified vertical profiles of Te(IV) and Te(VI) in the subarctic western North Pacific for the first time.

Solid-phase spectrophotometry for on-site analysis of trace elements in natural water.

A new, simple and sensitive solid-phase spectrometry (SPS) that is easily applicable to the on-site analysis of targeted chemical components in water at µg dm(-3) or sub-µg dm(-3) levels is proposed in this study. The main features of the SPS are the simplicity of operation, high sensitivity and applicability to real samples without the need for any pretreatment procedures. A portable spectrophotometer, consisting of an LED light source, a grating and a CCD, was used for the solid-phase light measurements. The universal applicability of the proposed system to on-site analysis was evaluated by determining phosphate, chromium(VI) and iron(II) in natural water.

Investigation of cadmium contamination using hair of the Japanese macaque, Macaca fuscata, from Shimokita Peninsula, Aomori Prefecture in Japan.

The cadmium (Cd) contents in hair of macaques (n = 45, Macaca fuscata) living on the Shimokita Peninsula were investigated. The mean Cd contents in the hair of Japanese (n = 34, 5.01 µg/g) and macaques (3.05 µg/g) tendency to be higher than those of animals living other areas. The Cd contents of hair of wild macaques were significantly (p < 0.01) lower than that of humans, although three were no significant difference between Cd contents of humans and that of the macaque in captivity. The hair of the macaque was suggested as a useful sample for measurement of Cd contamination in the environment.

Development and validation of a sensitive and fast solid-phase spectrophotometric procedure for phenol determination in pharmaceuticals.

A very sensitive, simple, and fast solid-phase spectrophotometric procedure for the determination of phenol using the p-nitrobenzenediazonium reagent (DAR reagent) was developed. This procedure is based on the simultaneous concentration of the orange product on a Dowex 1-X2 anion exchanger within 15 min, and a direct absorbance measurement of the sorbed species at both 530 nm (the absorption maximum of the phenol-DAR in the resin phase) and 700 nm (the range where only the resin absorbs light). Quality control and evaluation of the analytical parameters was carried out using a comprehensive prevalidation strategy. The linearity of the method was confirmed within an analyte working range from 0.01 to 0.10 µmol (0.2 to 2.0 nmol mL(-1)). The precision ranged from ±1.17 to ±9.61%; the accuracy ranged from -17.50 to +17.81%. The evaluated limiting values were L(D) = 0.0013 µmol and L(Q) = 0.0082 µmol. The DAR-SPS method was successfully applied to the determination of phenol in a pharmaceutical sample of salicylic acid (98.0-100.0%) and vaccines (98.0-103.4%).

Selective determination of trace iron in different oxidation states in natural water by flow injection-solid phase spectrometry.

A novel method for the selective determination of Fe(II) and Fe(III) in water using 2-nitroso-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (PSAP) was developed. QAE-Sephadex anion exchanger packed in a flow-through cell was used as a medium not only for both the concentration and the spectrophotometric measurements of the Fe-PSAP complex, but also for reduction of the Fe(III)-PSAP complex. The PSAP complex of Fe(II) or Fe(III) was strongly adsorbed on the anion exchanger in a weakly acidic to weakly basic region, but the Fe(III) complex was readily and completely reduced to the Fe(II) complex only in a neutral to weakly alkaline region in the solid phase. These properties were utilized to determine the Fe(II) and total Fe concentration without the addition of any reducing agent. The detection limits (3σ) were 0.18 ng for Fe(II) and 0.18 ng for total Fe using a 3.2-cm(3) sample solution. The present method is applicable to the determination of dissolved iron species present at µg dm(-3) levels in natural water samples.

Oxidation of chromium(III) by free chlorine in tap water during the chlorination process studied by an improved solid-phase spectrometry.

The oxidation of Cr(III) at naturally-occurring concentration levels, i.e., µg dm(-3) or lower levels, by free chlorine during the chlorination process of tap water was studied using an improved solid-phase spectrophotometric method, which can be directly applicable to the specific determination of Cr(VI) at µg dm(-3) or lower levels. The effect of the pH on the oxidation kinetics was investigated under three different pH conditions. The results showed that free chlorine oxidized the Cr(III) to Cr(VI), following the pseudo-first-order kinetics with half lifetimes of 3.0, 3.3 and 14.4 h at pH 5.0, 7.0 and 8.0, respectively, if the hypochlorite concentration was maintained at 4 mg Cl dm(-3).

Improved solid-phase spectrometry for the microdetermination of total and dissolved phosphate.

Solid-phase spectrophotometry has been improved for the determination of the total and dissolved phosphate in water. The target phosphate-P at sub-µg dm(-3) to µg dm(-3) levels in a 20-cm(3) water sample was concentrated as the molybdenum blue species to 0.06 or 0.12 cm(3) using a Sephadex G-25 within 30 min, and gel beads were introduced to a 1.5-mm or 3-mm diameter flow cell having a 10-mm light path length. To minimize the error caused by any difference in the packing state of the gel beads in the cell for each measurement, the absorbances of the blue color were directly measured at 836 nm and at 450 nm using a UV-visible spectrophotometer. The absorbance difference (ΔA) of the two wavelengths was used for determining the trace amounts of P. The sensitivity achieved by this procedure was higher by a factor of over 100 for a 20-cm(3) sample compared to that of the corresponding solution method using a 10-mm cell, and the detection limit was as low as 0.1 µg dm(-3). Higher sensitivity was obtained using 100 cm(3) water samples. Trace levels of the total and dissolved phosphate at sub-µg dm(-3) to µg dm(-3) levels in samples from mountainous small streams were directly determined without any preconcentration procedures.

Recent trends in solid phase spectrometry: 2003-2009. A review.

Around 100 papers published from 2003 to the present are reviewed concerning analytical methods for the direct light measurement of a solid phase in which a target colored or fluorescent analyte is concentrated. Recent attention has been paid to the development of flow injection-solid phase spectrometry as a simple and inexpensive tool for routine analysis of organic compounds or pharmaceuticals. Due to some improvements in flow injection analysis, such as sequential injection and lab-on-a-valve, it is possible not only to reduce the reagent consumption but also to devise fully automatic and miniaturized systems with minimal maintenance needs. This may have the potential of becoming one of the green analytical methods. Flow injection-solid phase spectrometry is expected to be applied to the speciation of trace chemical components (e.g., specific determination of trace metal ions in different existent oxidation states) in real samples in the environment.

Improved solid-phase spectrophotometry for the microdetermination of chromium(VI) in natural water.

A simple and sensitive solid-phase spectrophotometry procedure was improved for the microdetermination of Cr(VI). A 0.06 cm3 portion of a cation exchanger, Muromac AG 50W-X2, was used to concentrate the target Cr(VI) in a 20 cm3 water sample, and resin beads were introduced in a flow cell of 1.5 mm diameter and having a 10 mm light path length for measurements using a UV-visible spectrophotometer. Three lenses were used for focusing the incident light beam and for recovering light scattered by the solid phase in the cell. The sensitivity achieved was higher by a factor of 277 compared with that of the solution method, and the detection limit was 0.014 microg dm(-3). The recovery on spiked real water samples by the standard addition method was 96-101%. Favorable working and performance characteristics made it possible to directly determine sub-microg dm(-3) amounts of Cr(VI) in natural water samples.

On-line electrochemical oxidation of Cr(III) for the determination of total Cr by flow injection-solid phase spectrophotometry.

A novel on-line oxidation method of ultra-trace Cr(III) dissolved in natural water has been developed using a flow electrolysis cell. This method was successfully applied to the determination of the total Cr concentration by flow injection-solid phase spectrophotometry using diphenylcarbazide as a coloring agent. With the applied potential of 1.35 V (vs. Ag/AgCl) and the flow rate of 0.80 cm(3) min(-1), Cr(III) was quantitatively oxidized to Cr(VI) at room temperature. The total Cr concentration of sub-microg dm(-3) in 3 - 4 samples could be determined within 1 h using an aqueous sample volume of 7.1 cm(3). The analytical values of the total Cr concentration in natural water were in good agreement with those obtained by ICP-MS. The detection limit of the proposed method was 0.014 microg dm(-3) (3sigma, n = 7). This method could be applied to the specific determination of Cr(III) and Cr(VI) in river water samples.

Classification of the binding modes in bovine serum albumin using terminally substituted alkane analogues.

With the fluorescence probe of 8-anilino-1-naphthalenesulfonate (ANS), the binding modes of terminally substituted alkane analogues (C(n)X; X = COOH, OH, CHO, NH(3), CONH(2)) to bovine serum albumin (BSA) were investigated using a competitive binding technique. The Scatchard plot of the fluorometric titration of BSA with ANS showed that the maximum binding number of ANS, n(max), was 3.81, with the binding constant, K(bnd), of 1.42 x 10(6) mol(-1) dm(3). The binding modes of C(n)X to BSA were analyzed based on the fluorometric titration of the ANS and BSA mixture with C(n)X. C(n)COOH completely displaced the ANS bound to BSA, whereas C(n)OH and C(n)CHO displaced only about 40% of the ANS bound to BSA. In contrast, C(n)NH(2) and C(n)CONH(2) displaced very little bound ANS. By comparing these results, we classified the binding modes of C(n)X to BSA into three types. Two of them are detectable with the ANS fluorescence and the remaining one is not detectable with the fluorescence.

Determination of trace amounts of cobalt(II) by flow injection-solid phase spectrometry (FI-SPS) with 5-Br-PADAB.

Flow injection-solid phase spectrometry (FI-SPS) has been applied to the determination of cobalt(II) in water samples. The complex formed between cobalt and 5-Br-PADAB was on-line protonated and concentrated on an AG 50W-X2 cation-exchanger in a flow-through cell. The increase in absorbance caused by the accumulation of the complex in the resin was continuously measured. The interference by copper could be effectively eliminated by using EDDP as a masking agent. The detection limit was 40 ng dm(-3) with a 4.0 cm3 sample solution.

Experimental approaches to hyaluronan structure.

A review of the literature describing experimental studies on hyaluronan (HA) is presented. Methods sensitive to the hydrodynamic properties of HA, analyzed in neutral aqueous solution containing NaCl at physiological concentration, can be shown to fit the expected behavior of a high molecular weight linear semi-flexible polymer. The significant nonideality of HA solutions can be predicted by a simple treatment for hydrodynamic interactions between polymer chains. Nuclear magnetic resonance and circular dichroism studies of HA are also in agreement with a model incorporating dynamically formed and broken hydrogen bonds, contributing to the semi-flexibility of the polymer chain, and segmental motions on the nanosecond time scale. HA shows the capability for self-association in the formation of a viscoelastic putty state at pH 2.5 in the presence of salt, and a gel state at pH 2.5 in mixed organic/aqueous solution containing salt. Ordered and associated structures have also been observed for HA on the surfaces, especially in the presence of surface-structured water. These phenomena can be understood in terms of counterion-mediated polyelectrolyte interactions. The possibility that hyaluronan exists in vivo in environments that induce ordered structures and assemblies is discussed.

[Case of central nervous system lymphoma metastasized to breast after remission by methotrexate chemotherapy].

We report a case of primary central nervous system lymphoma (PCNSL) who responded well to initial systemic chemotherapy, but subsequently developed breast metastasis with local recurrence in the brain 27 months after complete remission. The 53-year-old female suddenly felt weakness in her left extremity. She was transferred to the emergency ward in our hospital. Neurological examination on admission showed disorientated state and mild hemiparesis. Brain MRI showed a well enhanced round lesion in the right basal ganglia with perifocal edema. A stereotactic biopsy of the tumor made a diagnosis of classic diffuse non-Hodgkin's B-cell type lymphoma. She received chemotherapy with a high-dose methotrexate under a condition of 20% of Karnofsky Performance Status (KPS). She enjoyed a useful life for about 5 years (KPS; 60-70%). Both recurrent and metastatic lesions responded poorly to various aggressive multiagent regimens of chemotherapy. An intensive initial treatment for the primary lesion and closely monitoring of the whole body at regular intervals are necessary for ensuring a long useful life.

Anion exchanger as a reaction/separation medium-absorptiometric determination of trace amounts of boron in waters by on-line complexation with chromotropic acid presorbed on the anion-exchange column.

A novel method of on-line absorptiometric determination for trace amounts of boron was developed based on the complexation with chromotropic acid presorbed on an anion-exchange column. On-line reaction and separation were achieved by controlling pH conditions in solutions to accelerate the 1:2 complex formation in the concentration process at pH 3 and to stabilize the complex in the separation process at pH 8. About 75% of the boron introduced into the stream was kinetically collected as the 1:2 complex on the column under the experimental conditions. The 1:2 complex was satisfactorily separated from excess reagent and matrix components by changing the concentration of NaClO4 in the eluent and its peak height on the chromatogram monitored at 350 nm was used for calibration. The sensitivity could be enhanced by increasing the sample amount introduced and the detection limits (3sigma) were 162 ng dm(-3) and 45 ng dm(-3) of boron, when 5.0 cm3 and 13.4 cm3 of the samples were used, respectively. The method has been successfully applied to the determination of boron in samples of river water, tap water and ion-exchanged water.

Entropy, Free Volume, and Cooperative Relaxation.

The high frequency end of the relaxation spectrum for polymer molecules involves the rotation of the segmental bonds. This fast relaxation process, however, cannot take place easily in the condensed state crowded by the densely packed conformers, necessitating the slower cooperatively synchronous relaxation. As the temperature is lowered, the domain of cooperativity grows towards the infinite size at the Kauzmann zero entropy temperature, though actually the system deviates from the equilibrium as the glass transition intervenes typically at 50 K above that temperature. The excess enthalpy and entropy drop faster than predicted by the rotational isomeric states which would reach zero only at 0 K. The real ΔCP is greater than that of the RIS value. The actual volume in excess of the crystalline lattice volume, however, points towards zero at 0 K. Thus, a polymer with higher Tg typically exhibits a lower density and modulus in the glassy state. Since the configurational entropy associated with the free volume is proportional to the logarithm of the latter, the Kauzmann temperature can be scaled by ln M, where M is the algebraic average of the conformer molecular weight. The temperature dependence of the most dominant, i.e., the largest equilibrium domain size will result in the Adam-Gibbs and Vogel equations for the characteristic relaxation time. The cooperative domain distribution leads to the relaxation spectrum that follows a power law. The relationship between the characteristic relaxation time and the rate of physical aging is derived.