Language：English   Publishing type：Research paper (scientific journal)  

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. © 2013 The Japan Society for Analytical Chemistry.

DOI： 10.2116/analsci.29.677

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

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 mu mol (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 mu mol and L-Q = 0.0082 mu mol. 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%).

DOI： 10.2116/analsci.28.397

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

B-11 NMR measurements showed that boric acid reacts with the polyol compounds, chromotropic acid, Tiron and 2,3-dihydroxynaphthalene-6-sulfonate, to form complexes with 1 : 1 and 1 : 2 stoichiometries. The equilibria of the complexation depend on the pH in the solution. The 1 : 2 complex is formed in an acidic or a neutral solution, while the 1 : 1 complex occurs in a higher pH range. Kinetic studies revealed that the reaction of 1 : 1 complex formation is much faster than that of 1 : 2 complex formation. A proton catalyzes both the reactions of 1 : 2 complex formation and its decomposition. On the basis of equilibrium and kinetic information, a novel method of on-line absorptiometric determination for trace amounts of boron was developed using a chromotropic acid presorbed anion-exchange column. On-line reaction and separation were achieved by controlling the pH conditions in solutions to accelerate 1 : 2 complex formation in the concentration process at pH 3 and to stabilize the complex in the separation process at pH 8. The 1 : 2 complex was satisfactorily separated from excess free ligand and matrix components by changing the concentration of NaClO4 in the eluent; its peak height on a chromatogram monitored at 350 nm was used for boron determination. The sensitivity could be enhanced by increasing the sample amount introduced, and the detection limit (3 sigma) was 0.05 mu g dm(-3) of boron when 13.4 cm(3) of the sample was used. The method has been successfully applied to the determination of trace boron in river water, ion-exchanged water and steels. Based on the electrochemical activities of respective species in the boron-chromotropic acid and boron-Tiron systems, methods for monitoring the boron concentration in RO desalination processes were also proposed.

DOI： 10.2116/bunsekikagaku.61.177

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

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 (3 sigma) 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 mu g dm(-3) levels in natural water samples.

DOI： 10.2116/analsci.28.225

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

The oxidation of Cr(III) at naturally-occurring concentration levels, i.e., mu g 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 mu g 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).

DOI： 10.2116/analsci.27.649

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The electrochemical detection of free chlorine based on the reduction at a gold electrode has been studied. The differential pulse voltammetric curves exhibited well-defined cathodic peaks. Investigations with this system suggested that the active species in the cathodic reaction is HClO. Excellent reproducibility was demonstrated at pH 5. The peak height could be used for accurate and rapid determination of free chlorine in a sample water. A linear relationship (r(2) = 0.99) was found for the concentration range of 1-5 mgCldm(-3) and the detection limit was estimated to be 0.04 mgCldm(-3).

DOI： 10.1002/elan.201000322

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

Solid-phase spectrophotometry has been improved for the determination of the total and dissolved phosphate in water. The target phosphate-P at sub-mu g dm(-3) to lig 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 (AA) 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 mu g dm(-3). Higher sensitivity was obtained using 100 cm(3) water samples. Trace levels of the total and dissolved phosphate at sub-fig dm(-3) to jig dm(-3) levels in samples from mountainous small streams were directly determined without any preconcentration procedures.

DOI： 10.2116/analsci.26.963

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

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. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.aca.2010.01.041

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

A simple and sensitive solid-phase spectrophotometry procedure was improved for the microdetermination of Cr(VI). A 0.06 cm(3) portion of a cation exchanger, Muromac AG 50W-X2, was used to concentrate the target Cr(VI) in a 20 cm(3) 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 mu g 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-mu g dm(-3) amounts of Cr(VI) in natural water samples.

DOI： 10.2116/analsci.25.1445

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The complexation ofboricacid with salicylic acid, salicyl alcohol and bis(hydroxymethyl)phenol derivatives has been investigated in detail using B-11 NMR spectroscopy. Boric acid accepts an electron pair through the nucleophilic attack of the ligand, followed by a condensation reaction, to form the 1: 1 monochelate complex. The monochelate complex then reacts with the ligand through the condensation reaction to give the 1:2 bischelate complex. Bis(hydroxymethyl)phenol derivatives formed quite stable chelate complexes among the examined salicyl derivatives. it was clarified by molecular modeling calculations that the complexation with bis(hydroxymethyl)phenol derivatives was highly favorable from an enthalpy viewpoint. An anion-exchange resin presorbed with 3,5-bis(hydroxymethyl)-4-hydroxybenzoate had a strong adsorbability of boron over a wide pH range. The adsorbent quantitatively removed boron up to approximately a half amount of the loaded ligand, which indicated that the boron species adsorbed onto the resin was predominantly present as the -3 charged 1:2 bischelate complex. The formation constant of the 1:2 bischelate complex with 3,5-bis(hydroxymethyl)-4-hydroxybenzoate in the resin phase was estimated to be log (beta) over bar (f(BLAc2)) = 5.0, which almost agreed with those of the salicyl alcohol derivatives in aqueous solutions. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2008.06.007

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Bioluminescence reaction by bacterial luciferase has been successfully controlled by a controlled-potential electrolysis using platinum-mesh electrode to regenerate the reduced form of flavin mononucleotide (FMNH2), which is one of the substrates of the reaction. It was found that the regeneration of FMNH2 is facilitated by the adsorbed hydrogen atoms formed on a platinum electrode surface in the presence of phosphate ions.

DOI： 10.1246/cl.2007.1358

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5182/jaie.18.524

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER WIEN  

A simple, sensitive and rapid solid-phase spectrophotometric procedure was developed for the determination of traces of phenol with 4-aminoantipyrine as a reagent (AAP-SPS), and the optimal experimental conditions were established. This method was performed by sorption and direct absorbance measurements of the product phenol-AAP sorbed on the anion-exchanger Dowex 1-X4 (0.2 g) at 495 nm (absorption maximum) and 700 nm (non-absorption wavelength). The sensitivity offered by the AAP-SPS procedure was higher by a factor of 40 compared with the respective conventional spectrophotometric method. Metrological characteristics were established using a prevalidation strategy. The AAP-SPS procedure is characterized by a linear calibration function in the working range of 0.05-0.50 mu mol, low standard deviation of procedure (+/- 0.012), low limit of determination (0.021 mu mol), and favorable random (+/- 0.85 to +/- 11.27%) and systematic deviations (-4.55 to +/- 11.50%). Moreover, the accuracy of the system investigated by the recovery test is acceptable (99-102%). Favorable working and performance characteristics make the new SPS method ideal for phenol monitoring in pharmaceutical preparations as well as other matrices.

DOI： 10.1007/s00604-007-0748-5

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A coupling sensitive solid phase spectrophotometric (SPS) procedure for determination of traces of heavy metals (Me-SPS) and multicomponent analysis by multiple linear regressions (MA), a simple methodology for simultaneous determination of metals in mixtures was inaugurated. The Me-SPS procedure is based on sorption of heavy metals on PAN-resin and direct absorbance measurements of colour product Me-PAN sorbed on a solid carrier in a 1-mm cell. This methodology (Me-SPS-MA) was checked by simultaneous determination of metals in synthetic mixtures with different compositions and contents of metals important in pharmaceutical practice: Zn, Pb, Cd, Cu, Co, and Ni. Good agreement between experimental and theoretical amounts of heavy metals is obtained from the recovery test (78.3-110.0%). The proposed method enables determination of particular metal ion at the ng mL(-1) level and it was successfully applied to the determination impurities from heavy metal traces in pharmaceutical substances (Cu in ascorbic acid, Pb in glucose, and Zn in insulin). The proposed procedure could be possible contribution to the development of pharmacopoeial methodology for a heavy metals test. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.talanta.2006.09.036

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

With the fluorescence probe of 8-anilino-1-naphthalenesulfonate (ANS), the binding modes of terminally substituted alkane analogues (CnX; X = COOH, OH, CHO, NH3, CONH2) 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 CnX to BSA were analyzed based on the fluorometric titration of the ANS and BSA mixture with CnX. CnCOOH completely displaced the ANS bound to BSA, whereas CnOH and CnCHO displaced only about 40% of the ANS bound to BSA. In contrast, CnNH2 and CnCONH2 displaced very little bound ANS. By comparing these results, we classified the binding modes of CnX to BSA into three types. Two of them are detectable with the ANS fluorescence and the remaining one is not detectable with the fluorescence.

DOI： 10.2116/analsci.22.1571

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

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-mu g dm(-3) in 3 - 4 samples could be determined within I 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 mu g dm(-3) (3 sigma, n = 7). This method could be applied to the specific determination of Cr(III) and Cr(VI) in river water samples.

DOI： 10.2116/analsci.22.1519

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

kFlow 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 cm(3) sample solution.

DOI： 10.2116/analsci.22.177

Web of Science

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

Solid-phase spectrometry (SPS) is based on the direct spectrometric measurement of solid phase which has sorbed a sample component. Direct application of the method mekes it possible to determine trace components in water samples without preconcentration. This method could be applied to a new type of FIA detection system, in which on-line detection with solid-phase retention of analytes is carried out. The sensitivity enhancement is easily accomplished by increasing the sample volume introduced. Analytes present in the mu g similar to sub-mu g dm(-3) range can be easily determined by using this system. The fundamental background and applicability of SPS and FI-SPS are described.

DOI： 10.2116/bunsekikagaku.54.1137

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Complex formation between vanadate and various ethanolamine derivatives (ethanolamine, diethanolamine, methyldiethanolamine, triethanolamine and ECTEOLA-Cellulose) has been examined in detail by using V-51 NMR spectroscopy. Vanadate binds with ethanolamine to form 1:1 (O)-monodentate and (N,O)-bidentate complexes which are protonated and deprotonated forms, respectively. Ethanolamine undergoes a comparatively weak interaction with vanadate relative to the other ligands. V-51 NMR spectra clearly show that vanadate reacts with the functional group of ECTEOLA-Cellulose, as well as diethanolamine, methyldiethanolamine and triethanolamine, which are analogues of the functional groups of ECTEOLA-Cellulose, to form the -1 charged 1:1 (N,O,O)-tridentate complex. In addition to anion exchange interaction of monovanadate and isopolyvanadate anions with the protonated functional group, in the alkaline region the adsorbability of vanadium(V) onto ECTEOLA-Cellulose is a consequence of the complexation of vanadate with the functional group. The formation constant of the (N,0,0) complex with ECTEOLA-Cellulose was estimated to be log beta((N,O,O)) = 3.6, which was almost the same as those with the analogues of the functional group. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2004.12.021

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

B-11 NMR spectroscopy provided direct evidence that boric acid reacts with Azomethine H to form a 1: 1 bischelate complex. A new peak with a -17.9 ppm chemical shift is due to the chelate complex containing tetrahedral boron. It has been quantitatively confirmed that the reaction includes two chemical equilibria;, one is related to the ligand formation and the other to the complex formation. The formation constant for the ligand is small, less than 10, whereas that for the complex is relatively large, greater than 10(5). Azomethine H is hydrolyzed in aqueous solution because of its low stability, and the ligand formation is responsible for the nature of its complexation with boric acid. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2003.12.016

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5182/jaie.14.Supplement_313

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5182/jaie.14.Supplement_33

CiNii Article

CiNii Books

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

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 cm(3) and 13.4 cm(3) 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.

DOI： 10.1039/b207869d

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG  

Solid phase absorptiometry was applied to the simultaneous flow analysis of trace metals in combination with a micro black flow-through cell packed with ion exchanger beads and a multi-channel photodetector connected with optical fibers. A 4.0 cm(3) sample solution containing five rare earth metal ions (Dy, Ho, Tm, Er and Nd) was introduced into a flow system and these metal ions were concentrated on a cation exchanger (Muromac 50W-X4) in a flow-through cell. The absorbance increases originating from the f-f or d-f transition bands of these metal ions were directly and continuously measured at 910 nm for Dy, at 530 nm for Ho, at 683 nm for Tm, 522 nm for Er and at 790 nm for Nd, respectively. A multi-variable analysis method was combined with the flow analysis because the absorption spectra of the five rare earth metal ions partly overlapped one another. Although no coloring reagents were used, the proposed method was about 200 times more sensitive than the corresponding solution method. The reproducibility of this method was less than +/- 5%. The detection limits were 0.03, 0.40, 0.30, 0.35 and 0.23 mg dm(-3) for Dy, Ho, Tm, Er and Nd, respectively. Five rare earth metal ions could be precisely determined in practical samples such as yttrium concentrate.

DOI： 10.1007/s002160000515

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACS  

Boron adsorption behavior on cross-linked polysaccharide anion exchangers, QAE-Sephadex and QA cellulose, was examined in detail by 11B NMR measurements and distribution studies. For the QAE-Sephadex system, two signals of 1:1 borate complexes with α,β and α,γ-diol moieties of the glucopyranoside residues were observed, showing identical chemical shift values with those for the Sephadex gel system. Only the 1:1 complex of borate with α,β-diol moiety of the gel matrix was formed for QA cellulose. The formation constants of the borate complexes, estimated by the signal intensities of 11B NMR, were almost the same in the anion exchangers and Sephadex gel. The adsorbability of boric acid/borate was not enhanced as much by the presence of charged functional groups, because both the ion-exchange selectivity toward borate and formation constants of borate complexes with the gel matrix are not so high. The pH in the anion exchanger phase is higher than that in the external equilibrated solution, however, is slightly lower than the value expected from the Donnan relation, as a result of the fixation of anionic borate onto the gel matrix by the complexation: -log[H+]̄ = -a log[H+]+b(α≤1 and b&gt
O). Boron adsorption behaviors on the polysaccharide anion exchangers, such as pH dependence, boron concentration dependence, and background electrolyte effect, can be explained satisfactorily on the basis of such properties.

DOI： 10.1021/ma991257o

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The complexation of boric acid with chromotropic acid in aqueous solution was examined thoroughly by B-11 NMR measurements. Two peaks with chemical shift values of delta -17.7 and -18.0 were observed besides the free boric acid/borate peak and ascribed to the 1:1 and the 1:2 complexes, respectively. The 1:2 complex is formed in acidic solution, while the 1:1 complex prevails in a higher pH range. The formation constants for these complexes were evaluated based on the signal intensities of B-11 NMR spectra to be log beta(1)=-1.57 and log beta(2)=2.35, which are well consistent with those reported previously as well as that (beta(2)) obtained kinetically in this work. The chromatographic separation of the 1:2 complex from the other species enabled a kinetic study of the reaction which revealed that the reaction for 1:1 complex formation takes place much faster than that for 1:2 complex formation. The pH dependences of the rate constants of the forward and backward reactions of the 1:2 complexation could be interpreted by the catalytic role of hydrogen ions in the reactions. Plausible mechanisms for both the reactions of 1:2 complex formation and decomposition were proposed. On the basis of the equilibrium and kinetic information on the complexation, the optimum conditions for practical applications of the ligand so far reported could be well understood.

DOI： 10.1039/b004399k

Web of Science

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEM  

The applicability of solid-phase spectrometry to flow analysis has been studied for the sensitive determination of target trace elements in natural-water samples. By a fundamental study involving light measurements, it has been confirmed that Beer's law can be applied to around the 4 to 5 absorbance scale in a solid particle layer system. Lambert's law was also confirmed up to a cell length of 4 cm if the Pt tube cell was used. On the basis of obtained data, a flow-through cell packed with fine spherical beads has been tested as a detector in flow-analysis systems for the sensitive determination of some elements such as cobalt(II), chromium, copper(II), molybdenum (VI) and vanadium as well as some rare earth elements and aluminium. By only using a few cm(3) of the sample solution, the proposed method enabled us to determine the target chemical species present at mu g dm(-3) or lower levels in 3-6 samples in less than 1 hour. By a practical application of the proposed method to natural-water analysis, some significant information, unavailable by other determination methods, could be obtained: for example, details on die oxidation states of chromium present at sub-mu g dm(-3) levels in natural water.

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Specific determination of chromium(III) and chromium(VI) in natural water samples was performed without mutual separation. The chromium in sample solution was concentrated on cation-exchange resin packed in a flow-through cell as a reaction product of chromium(VI) with diphenylcarbazide. The absorbance increase caused by the accumulation of the complex on cation-exchange resin was continuously measured. By using peroxodisulfate as an oxidizing agent, the chromium(III) in sample solution was completely oxidized to chromium(VI). The chromium(III) concentration was calculated by the difference between the values of the total chromium and chromium(VI). The detection limit for chromium(VI) and total chromium was 70 pg and 120 pg, respectively. This method was applied to the specific determination of chromium in several natural water samples. The results of the total chromium obtained by the proposed method show moderate agreement with that obtained with ICP-MS. Unlike the previous results reported in chromium speciation studies, the predominant chromium species in natural water was chromium(VI).

DOI： 10.1039/a900493i

Web of Science

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEM  

The applicability of solid-phase absorptiometry to a minute solid particle has been studied for the sensitive determination of target trace elements present in a small volume of sample solutions. An iron(II)-phenanthroline complex or a Cr(VI)-diphenylcarbazide complex in 1 cm(3) of a sample solution was concentrated in a spherical bead of cation-exchange resin having a particle size of about 0.8 mm. The light attenuance of this par tide was measured using a polarizing microscope attached to a photo-detector. The sensitivity of the proposed method was 280-times greater than that of the conventional corresponding solution method, which was considered to agree with the expected value of 300. Although the size of the respective cation-exchange resin particle was not very uniform, a reproducible measurement of the absorbance due to the colored chemical species sorbed could be made. The calibration graph was straight and Beer's law could be also applied, even to a minute spherical bead.
The proposed method is thought to be effective for analyzing trace elements in samples which are hardly obtained in large amounts, such as rain-water samples.

DOI： 10.2116/bunsekikagaku.47.335

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry  

N-Methylglucamine resin has been shown to be a good adsorbent for borate or boric acid. Above ca. pH 6, the boron adsorbability of this resin increased with a maximum around pH 9. The maximum distribution ratio was higher than 106, however, further increase in pH resulted in a decrease in the distribution ratio. The combination of distribution and 11B MAS NMR measurements revealed the formation of a 1:1 tetradentate complex of B(OH)4 - with the N-methylglucamine group. The calculated pH-dependence of boron adsorption agreed well with the experimental results with respect to the -log [H+] values in the resin phase (not in the external solution) estimated by 31P NMR measurements. The maximum adsorption around pH 9 of the equilibrated solution is due to the fact that the pH in the resin phase remains higher than that in the external solution. Therefore, B(OH)3/B(OH)4 - is selectively concentrated into the resin phase and by the dehydration condensation B(OH)4 - forms the 1:1 tetradentate complex with the anchor group. The overall formation constant of the complex was estimated to be 104.0±0.1, which was almost the same magnitude as that of the 1:1 monochelate complex with an α,β-diol site of N-methyl-D-glucamine (which is an analogue of the functional group of the resin) in aqueous solutions of pH 5.1-7.4. However, the binding structures of each 1:1 complex with the N-methyl-D-glucamine group are quite different in the aqueous solution and in the crosslinked polymer.

DOI： 10.1039/a707790d

Scopus

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Ion-exchanger phase visible light absorptiometry combined with flow analysis has been developed and applied for the determination of vanadium in natural water and rock. The vanadium(IV) and vanadium(V) in the sample solution reacted with xylenol orange (XO) which was immobilized on the AG 1-X2 anion-exchanger packed in flow-through cell, and the increase in light absorption caused by the formation of the vanadium-XO complex in the resin was directly measured with a spectrophotometer at 532 nm. The interference by most of the co-existing ions can be effectively eliminated using trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid (CyDTA) and ammonium tartrate. The detection limit was 80 ng dm(-3) with 5.0 cm(3) of sample solution. Vanadium contents in three sample solutions could be determined within 1 hour.

DOI： 10.1016/0003-2670(95)00412-2

Web of Science

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Ion-exchanger phase absorptiometry was applied to flow analysis for trace amounts of copper in water. The increase in the absorbance of the coloured complex with 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline disulphonate, which was concentrated on-line on to an ion exchanger packed in a flow-through cell, could be measured continuously with a spectrophotometer at 484 nm. The detection limit was 0.08 ng cm-3 with 8.3 cm3 of sample solution. The proposed method permitted a highly sensitive, selective determination of copper in karst groundwater samples without any preconcentration. By measuring the copper concentration response in water after a storm, the infiltration rate of rain water from the soil zone to the underground river of a karst groundwater system could be evaluated to be about 10-20 m day-1.

DOI： 10.1016/0003-2670(92)85216-S

Web of Science

researchmap

Language：English   Publishing type：Research paper (bulletin of university, research institution)   Publisher：Kyushu University  

CiNii Article

CiNii Books

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The fluorescence bands originating from d→f electron transitions, which can be used to determine europium, terbium, dysprosium or samarium selectively, were enhanced only if these elements were sorbed in a weak-acid cation-exchange gel, i.e., CM-Sephadex. After a sample solution had been introduced into a fused-silica tube (1.5 mm i.d.) packed with 1 mg of CM-Sephadex, the fluorescence intensity increase, resulting from the rare earth elements sorbed in the ion-exchange gel, could be measured directly with good precision. For europium, the detection limit was 22 ng with an 8.3 cm 3 sample solution. The sensitivity of the proposed method depended on the sample volume introduced. The cell could be used repeatedly after desorbing the target element with a solution of nitric acid.

DOI： 10.1039/an9921700189

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER APPL SCI PUBL LTD  

Web of Science

researchmap

Language：English   Publishing type：Research paper (bulletin of university, research institution)   Publisher：Kyushu Univ.  

researchmap

Language：English   Publishing type：Research paper (bulletin of university, research institution)   Publisher：Kyushu Univ.  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：KODANSHA LTD  

Web of Science

researchmap

Language：English   Publishing type：Research paper (bulletin of university, research institution)   Publisher：Kyushu Univ.  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Ion-exchange absorptiometry combined with flow analysis has been applied to the determination of trace amounts of molybdenum(VI) in natural water and rock. By using a pretreatment column packed with Sephadex G-25 gel, molybdenum(VI) in a sample solution can be sorbed selectively on the gel at pH 3.5. The molybdenum(VI) in the column was desorbed with EDTA as the molybdenum(VI)-EDTA complex, and the solution was introduced into a Tiron solution stream. The yellow complex formed between molybdenum(VI) and Tiron in the flow system was then concentrated on a QAE-Sephadex A-25 anion exchanger packed in a flow-through silica micro-cell. The attenuation of incident light by the molybdenum(VI)-Tiron complex on the anion exchanger in the cell was continuously recorded with a spectrophotometer at 410 nm. The complex on the anion exchanger was easily desorbed with sodium nitrate, so the flow-through cell could be used repeatedly. The minimum amount that could be detected corresponded to 15 ng of molybdenum(VI). Molybdenum(VI) in three or four sample solutions could be determined within 1 h. © 1989.

DOI： 10.1016/S0003-2670(00)84620-6

Scopus

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：Advanced Instrumental Analysis Kyushu University  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：日本分析化学会  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：日本分析化学会  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：The Japan Society for Anlytical Chemistry  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：九州大学中央分析センター  

researchmap

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：日本分析化学会  

researchmap