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Volume 54, Issue 12
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Toshihiko IMATO2005 Volume 54 Issue 12 Pages 1123-1136
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSFlow analysis has many advantages concerning sensitivity, accuracy, repeatability and analytical throughput etc, compared with a batchwise analysis. The flow-based method makes the involved analytical processes automatic and rapid. Therefore, the combination of a chemical sensor with the flow method enhances the performances of the chemical sensor. Especially, potentiometric detection using ion-selective electrodes has been widely used in flow analysis due to its features, simplicity in analytical operation and wide dynamic range in analysis. This paper reports on several chemical sensors applied to flow systems that we have engaged so far concerning: (1) Liquid membrane type ion-selective electrodes, such as nitrate, vitamin B1, tetrafluoroborate and surfactants sensitive electrodes based on an oleophilic anion exchange resin membrane and a hydrophobic ion exchanger. (2) Flow titration by using both a buffer solution and its corresponding electrode, such as a pH glass electrode with a pH buffer, a cupper(II) ion-selective electrode with a metal ion buffer solution and a redox electrode with a potential buffer solution. (3) Surface plasmon resonance sensors for succarides and some endocrine disrupting chemicals based on a boronic acid polymer membrane and antigen or antibody immobilized membrane. (4) Sequential injection analysis combined with beads injection technique for vitellogenin as biomarker for assessing the pollution of environment in hydrosphere.
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Shiro MATSUOKA, Kazuhisa YOSHIMURA2005 Volume 54 Issue 12 Pages 1137-1147
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSSolid-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 μg∼sub-μg dm−3 range can be easily determined by using this system. The fundamental background and applicability of SPS and FI-SPS are described.
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Research Paper
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Yoichi SHIBUSAWA, Naoko TAKEUCHI, Heisaburo SHINDO, Yoichiro ITO2005 Volume 54 Issue 12 Pages 1149-1154
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSPhospholipids were fractionated by high-speed counter-current chromatography in a one-step operation from about 0.75 g of hen egg yolk using a type J-multilayer coil planet centrifuge. The partition coefficients values of phospholipids were measured in several two or three-solvent systems. The separation of phospholipids was performed with a two-phase solvent system composed of chloroform/n -heptane/n -butanol/methanol/60% acetic acid (2 : 3 : 2 : 3 : 5) by eluting the lower phase at a flow-rate of 1.0 ml/min. The phospholipids in each fraction were characterized by thin-layer chromatography.
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Yoriko SASAKI, Aki DAIKOKUYA, Isoshi NUKATSUKA, Kunio OHZEKI2005 Volume 54 Issue 12 Pages 1155-1160
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSA flow injection spectrophotometric method for the determination of ammonia and formaldehyde was developed, in which ammonia and formaldehyde were determined with almost the same FIA manifold. The color development reaction of ammonia is based on the formation of an indonaphthol dye in the presence of hypochlorite and 1-naphthol. The FIA system consisted of three flow paths: a carrier (water), a NaClO solution, and a 1-naphthol solution in a mixed solvent (ethanol : acetone : water = 2 : 1 : 2), with flow rates of 0.2, 0.2, and 0.4 ml min−1, respectively. A monochloramine and an indonaphthol dye were formed in a reaction coil (RC1) and a reaction coil (RC2), respectively. The optimum conditions were thoroughly studied by varying the reagent concentrations under a fixed flow rate. The results showed that the optimum conditions were 0.25 M NaOH and 2.0% active chlorine for a NaClO solution, and 1.6% of 1-naphthol. The lengths of the required reaction coils were 3 m and 7 m for RC1 and RC2, respectively. A linear calibration graph was obtained in the range of 0∼2 μg ml−1, and the detection limit, based on three-times the standard deviation of a blank, was 15 ng ml−1. Formaldehyde was determined indirectly using the reaction with ammonia to form hexamethylenetetramine. The residual ammonia was determined with the same FIA system, except that RC1 was replaced by a 20 m reaction coil. The concentration of active chlorine was set to 1.2%. A linear calibration graph was obtained in the range of 0∼1 μg ml−1, and the detection limit was 13 ng ml−1. The time required for the analysis of one sample was 8.1 min for ammonia and 14.8 min for formaldehyde. The time interval required for successional injection of the sample was about 5.5 min in both methods. The proposed method was applied to obtain a decay curve of formaldehyde in a test chamber in the absence or presence of an absorbent for formaldehyde. It was found that an ammonium sulfate solution is effective to absorb formaldehyde in air.
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Makoto HARADA, Tomo-o KIDO, Tetsuo OKADA2005 Volume 54 Issue 12 Pages 1161-1168
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSTheoretical simulations have been conducted to explain the elution profiles of solutes passed through an open capillary and to analyze the potential usefulness of this simple technique as a separation method. The advection-diffusion equation for a cylindrical geometry has been numerically analyzed with a CIP method, which is known to be a suitable method for numerical simulations of differential equations. The profile of the solute distribution in a capillary can be characterized by four factors: the diffusion coefficient of the solute, the flow rate and the radius and length of the capillary. The reduction time (τav) is a very good measure to represent the diffusivity of a solute; it is diffusive when τav>1, but nondiffusive when τav<1, as stated in our previous papers. A diffusive solute is carried by the average flow, and gives a Gaussian-shaped peak, while a nondiffusive solute moves along the Poiseuille flow profile in the capillary and produces an asymmetrical peak appearing earlier than the former. The mechanisms for the production of these different peak profiles have been discussed in detail based on the results of a simulation. Although two solutes can be separated based on this separation principle, the heavy peak-tailing of the asymmetric peak makes complete separation difficult. To reduce the tailing, several possibilities for sample introduction and effluent collections have been proposed. Numerical simulations have suggested that such improvements result in a much better separation performance.
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Yuko TOMOTSUNE, Tomohiko KAWAKAMI, Satoshi TOMATSURI, Tsuneyuki NOGUCH ...2005 Volume 54 Issue 12 Pages 1169-1174
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSConcerning analysis in a microfluid, so-called μTAS, the precision of the analysis is greatly affected by the flow-rate precision of the pump used. In response to this required precision of the pump, we have developed a gas-pressurized micro fluidic pump (μFPump) without any pulsation. Its applicability was examined by comparing the precision to that of a currently used pump, such as a micro-syringe pump and a diaphragm pump. The precision was compared through a model analysis, a quantitative analysis of nitrite ion in JIS K 0102 (Industry drainage examination under Japanese Industrial Standards), using a glass-made microchemical-chip as a reaction chip and a Thermal Lens Microscope as a detector. As a result of the comparison experiment, in the case of an analysis using our μFPump, a coefficient of variation (CV) of 0.7∼2.0% and a detection limit (3σ) of 0.0058 μg/ml were obtained, and it was clarified that a several-fold higher analytical precision than that of using the other pumps can be obtained. Moreover, the experiment indicates that a pump with stable flow without pulsation is necessary to carry out an accurate analysis in a microfluid.
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Kiyoko KUROSAWA, Katsuyoshi TATENUMA, Manabu MUTO, Hiroyasu ESUMI, Yuk ...2005 Volume 54 Issue 12 Pages 1175-1182
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSIn order to measure a small amount of constituent in gaseous samples, such as measuring the causative substances of the sick-house syndrome, according to general solid-phase adsorption, complicated handling, such as solvent extraction, or concentration and heating desorption, are required. Consequently, we have developed a simple and highly accurate continuous gas sampler consisting of a denuder and a cross flow nebulizer. An absorbing solution and gaseous sample are simultaneously introduced to the nebulizer, and a droplet absorbent is then flowed in the inner wall of the denuder tube, while contacting with the gaseous sample. By optimizing the flow ratio between the gaseous sample and the absorbent, the targeted constituent in the gaseous sample is efficiently absorbed into the absorbent while flowing in the tube. By experiments being currently conducted, in the case of formaldehyde recovery under the condition of a gaseous sample flow rate of 2.0 l/min and an absorbent (purified water) flow rate of 0.1 ml/min (volume ratio of gaseous sample/absorbent = 20000 : 1), a recovery rate of 95% or more was stably and continuously obtained, and a concentration of less than 1/10 of the regulated formaldehyde concentration in a room can be analyzed without any extraction or concentration procedures. We will apply this simple gas sampler to practicable technologies, such as the recovery of other volatile organic compounds (VOC) constituents, an on-site sick-house monitoring system with a detective device, and cancer diagnosis using expiratory air.
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Tadao SAKAI, Shun-ichi FUJIMOTO, Keiro HIGUCHI, Norio TESHIMA2005 Volume 54 Issue 12 Pages 1183-1188
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSAn automatic flow injection method was proposed using the on-line solid-phase extraction of trace phenols and color development with 4-aminoantipyrine. Phenols at low levels in water samples were pre-concentrated onto OASIS HLB for 20 min at 2 ml min−1. After elution, color development occurred in the merging zone with 4-aminoantipyrine buffered at pH 10 and hexacyanoferrate(III). The absorbance was measured at 505 nm. The calibration graph for phenol was linear over the range of 0.25∼10 ng ml−1 with RSD<1%. The proposed method could be applicable to the analysis of phenols in tap and river water.
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Masato SUZUKI, Tomoyuki YASUKAWA, Hitoshi SHIKU, Tomokazu MATSUE2005 Volume 54 Issue 12 Pages 1189-1195
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSThe dielectrophoretic separation of micro-organisms, based on cellular membrane damage, was carried out using a microfabricated fluidic device. The fluidic device was composed of an indium-tin oxide electrode with castellated electrode patterns, an acrylic board with inlet and outlet holes for micro-organisms suspension, and a silicone separator with a fluidic channel (width, 2 mm; length, 35 mm) between the electrode substrate and acrylic board. Dielectrophoretic separation was demonstrated for a mixture of live and heat-treated Escherichia coli bacteria labeled by fluorescent stains. The mixture was injected into the fluidic device at a flow rate of 440 μm/sec. Both live and dead bacteria were collected around castellated electrode when an alternative (sinusoidal) electric field (frequency 100 kHz, voltage 20 Vpeak-to-peak) was applied to the castellated electrode. The dielectrophoretic separation was found by changing the electric field frequency from 100 kHz to 7 MHz. Only the heat-treated E. coli cells were flown out from the fluidic device, while the live E. coli cells remained being captured between the electrodes. The results demonstrated that the fluidic device equipped with a microelectrode array provides a convenient way for the dielectrophoretic concentration and separation of targeted bio-particles in biomedical applications.
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Yasushi HASEBE, Takayuki SHIRAI, Tomohiro NAGASHIMA, Tingting GU, Shun ...2005 Volume 54 Issue 12 Pages 1197-1204
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSThionine (TN) was adsorbed onto a porous carbon felt (CF) electrode surface, and the resulting TN-modified CF (TN-CF) was successfully used as a working electrode unit in a flow-through electrocatalytic detector, which enabled both the amperometric and coulometric determination of NADH at the μM concentration level. The anodic peak current due to the electrocatalytic oxidation of NADH was optimized for the highly sensitive amperometric and coulometric determination of NADH. The optimum conditions for the amperometric determination of NADH were the applied potential; + 0.2 V (vs. Ag/AgCl); the carrier pH, 8.0 (0.1 M phosphate buffer); and the carrier flow rate, 2.5 ml min−1. The calibration curve of NADH, plotting the peak current vs. NADH concentration, is linear from 1 μM to 100 μM, with a detection limit of 0.5 μM. The reproducibility of the measurements was 1.35∼1.70% RSD (n = 10). The determination speed was up to 72 samples per hour at a flow rate of 3.5 ml min−1. In order to enhance the coulometric efficiency, a slower flow rate and a smaller sample volume were preferable. When the carrier flow rate was less than 0.8 ml min−1 and the sample volume was 20 μl, the charge efficiency for 100 μM NADH reached almost 100%, which enabled an absolute assay of NADH without any calibrations.
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Technical Paper
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Masaaki YOSHIWARA, Akio SAKURAGAWA, Amane MITSUHASHI2005 Volume 54 Issue 12 Pages 1205-1210
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSA flow injection system was developed for the determination of creatinine as an index of the progression of chronic renal failure, with an immobilized enzyme-reactor column. This system consisted of a hand-made reactor column packed with creatinine deiminase immobilized onto chitosan beads (CD-IE) as a carrier and utilized the glutaraldehyde bridging method by forming a Schiff base. Using a phosphate buffer solution as a carrier, the sample solution is injected into the stream. The injected sample solution is converted to ammonia by CD-IE reactor column, and the solution is made into a basic medium with potassium hydroxide. It is then introduced into a gas-diffusion device, and mixed with cresol red and 2-{4-(2-hydroxyethyl)-1-piperzinyl}-ethanesulfonic acid. The absorbance is measured at wavelength of 555 nm. In this study, it was converted from creatinine to ammonia by CD-IE reactor column, and creatinine was determined indirectly by the concentration of ammonia. Creatinine in the control urine for the proofreading of the automatic urine analysis was determined by applying the standard addition method. It was almost agreed with the reference value.
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Note
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Kenichiro TODOROKI, Masae ARISAKA, Yoshihiko NAKASHIMA, Hideyuki YOSHI ...2005 Volume 54 Issue 12 Pages 1211-1214
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSWe have developed a fluorescence derivatization method of 5-hydroxyindoles (serotonin, 5-hydroxyindole-3-acetic acid, N -acetylserotonin) based on benzylamine derivatization, followed by photocatalytic oxidation. In the present study, a photocatalyst, which was titanium dioxide supported on a diatomaceous earth particle, was used instead of potassium hexacyanoferrate(III) as a chemical oxidizing agent employed in the conventional method. The resulting fluorescent derivatives were separated by reversed-phase liquid chromatography on an ODS column by using a mixture of acetonitrile and 250 mM acetate buffer (pH 4.6) and detected spectrofluorimetrically at 465 nm with excitation at 350 nm. The detection limit (signal-to-noise ratio = 3) for N -acetylserotonin was 16 fmol per 20 μl injection.
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Kenji YOSHIKAWA, Miho OKAMURA, Miki INOKUCHI, Akio SAKURAGAWA2005 Volume 54 Issue 12 Pages 1215-1218
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSFrom the viewpoint of a graphite carbon column with excellent durability, it was applied to the ion chromatography (IC) of several organic acids. The carbon column was permanently coated with the cetyltrimethylammonium ion, and the elution behaviors of several organic acids (acetic acid, lactic acid, succinic acid, malic acid, tartaric acid, citric acid) and inorganic anions (Cl−, NO2−, NO3−, SO42−) were examined according to an ion chromatography that combined conductivity detector using a mobile phase of the benzoic acid system, when an ion-exchange ability was given to the graphite carbon column. Tartaric acid and citric acid, etc. with large valency showed tendency to which the width of each peak extended and the retention time increased. However it was possible to separate excellently for the analytes detected within ten minutes. The calibration curves obtained from the peak areas for the organic acids and inorganic anions were linear, with good correlation coefficients of 0.999. The relative standard deviations (RSD) of the peak areas were between 0.4 and 1.0 for six repeated measurements. The developed method was then applied to the determination of organic acids in several food samples.
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Tomoko NAKANO-OHTA, Takashi SAITO, Jun SATO2005 Volume 54 Issue 12 Pages 1219-1222
Published: 2005
Released on J-STAGE: April 06, 2006
JOURNAL FREE ACCESSRadium isotopes (228Ra and 226Ra) in river-water samples from Japan having low concentrations were attempted to be collected by a Mn-impregnated acrylic fiber. The method was aimed at the in-situ collection of Ra isotopes in large amounts of river water by making effective use of the flow of the river to observe the 228Ra/226Ra activity ratio. Measurements of the 228Ra/226Ra activity ratios were made by non-destructive γ-ray spectrometry. Although the collection efficiency of Ra isotopes by Mn-impregnated acrylic fiber was observed to be dependent on the water pH and temperature, the Ra isotopes in river water in an effective range of pH and temperature could be successfully collected. The 228Ra/226Ra activity ratios observed in several rivers of Japan by the present method were in the range of 1.1∼2.9, which is slightly higher than those observed in rivers of the continental area.
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