Vol. 54 No. 7
July, 2005
Zilin Chen1, Hsueh-Chia Chang1 and Toshiyuki Hobo2
1 Center for Micro-fluidics and Medical Diagnostics, Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA(Received 21 February 2005, Accepted 18 April 2005)
It has been known that monolithic porous silica possesses the morphology of a continuous skeleton, micro-scaled through-pore and nano-scaled meso-pore on the skeleton. It is its unique morphology that shows great promise for applications in the fields of analytical chemistry. This paper describes advances in successful applications of monolithic silica to analytical chemistry, achieved in authors' groups. The authors focused their work on three main subjects regarding monolithic silica: (i) a chemically modified monolithic silica column for chiral separation in capillary electrochromatography and micro-liquid chromatography, (ii) a monolithic enzyme reactor integrated with a biosensor for continuous monitoring (bimolecules), and (iii) an electroosmotic micropump for micro flow analysis and electrospraying.
Keywords : chiral separation; monolithic column; capillary electrochromatography; micro-liquid chromatography; biosensor; enzyme reactor; micropump; flow injection analysis; electrospray.
Eri Ayano1 and Hideko Kanazawa1
1 Physical Pharmaceutical Chemistry, Kyoritsu University of Pharmacy, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512(Received 25 February 2005, Accepted 18 April 2005)
We developed a novel chromatography system in which temperature controlled separation is achieved by only water as a mobile phase using packing materials modified with a temperature-responsive polymer, poly (N-isopropylacrylamide) (PNIPAAm). The ability of the proposed temperature-responsive chromatography system to separate solutes without using an organic solvent is advantageous from the point of view of maintaining the structure and activity of biologically active substance. Recently, we designed and synthesized copolymers that introduced ion-exchange groups, environmentally-responsive polymers, which respond to temperature and pH. Copolymer-grafted aminopropyl silica beads were used as HPLC packing materials. These separation systems are based on a new concept that the property of the stationary phase surface is altered by external stimuli, such as the pH and temperature. A temperature-responsive chromatography system utilizing PNIPAAm derivatives would be highly useful for peptide and protein separation, since chromatographic separation is performed under mild aqueous mobile phase conditions. Applications to bio-separation in various fields, such as medical and pharmaceutical sciences, is expected.
Keywords : temperature-responsive polymer; poly (N-isopropylacrylamide); environmentally-responsive chromatography; bio-separation.
Shogo Suzuki1, Yukiko Okada1 and Shoji Hirai1
1 Faculty of Engineering, Musashi Institute of Technology, 1-28-1, Tamazutsumi, Setagaya-ku, Tokyo 158-8557(Received 22 December 2004, Accepted 19 May 2005)
Trace element concentrations in scallop reference material and fish otolith certified reference materials prepared at the National Institute for Environmental Studies (NIES) of Japan were determined by instrumental neutron activation analysis (INAA). Nine aliquots of scallop sample (ca. 252~507 mg) and five aliquots of fish otolith sample (ca. 502~988 mg) and comparative standards were irradiated for a short time (10 s) at a thermal neutron flux of 1.5×1012 n cm-2 s-1 (pneumatic transfer) and for a long time (6 h) at a thermal neutron flux of 3.7×1012 n cm-2 s-1 (central thimble) in the Rikkyo University Research Reactor (100 kW). The irradiated samples were measured by conventional γ-ray spectrometry using a coaxial Ge detector, and by anti-coincidence and coincidence γ-ray spectrometry with a coaxial Ge detector and a well-type NaI(Tl) detector to determine as many trace elements as possible with high sensitivity. The concentrations of 34 elements of the NIES No.15 scallop referrence material and 16 elements of the NIES No.22 fish otolith CRM were determined. Using the coincidence counting method to determine Se, Ba and Hf, the lower limit of the determination was improved by 2 times compared with the conventional counting method.
Keywords : instrumental NAA; certified reference material; scallop; fish otolith; anti-coincidence γ-ray spectrometry; coincidence γ-ray spectrometry.
Junichi Sugiyama1, Kosuke Tanaka1, Akinori Igarashi1 and Kuniaki Adachi1
1 Analytical Research Center, Research & Technology, LION corporation, 7-13-12, Hirai, Edogawa-Ku, Tokyo 132-0035(Received 15 March 2005, Accepted 24 May 2005)
In this study, we examined a separation analysis method for amino modifier silicones (AMS) and dimethylsilicones (DMS) in hair rinses. Generally, size-exclusion chromatography (SEC) is used for the analysis of silicones. However, SEC cannot separate AMS and DMS by the size-exclusion principle only when the molecular weights are nearly the same. Therefore, we examined the derivatization method of AMS and a separation method for AMS and DMS by SEC-UV-RI (SEC with an ultraviolet detector and a refractive index detector). After an analysis, we were able to detect and determine only the amount of AMS by the derivatization of AMS with N-succinimidyl 4-nitorophenylacetate (SNPA) by using UV (280 nm), and were also able to determine the total silicone (AMS and DMS) amounts by using RI. In addition, the DMS amount was given by subtracting the AMS amount from the total silicone amounts. The recovery rates from model hair rinses were good, and the results were reproducible, except for a portion. Moreover, the chromatograms and molecular weights were in good agreement with the raw materials. In addition, we established a method for calculating the modified rates of AMS by using the analysis method described above.
Keywords : amino modifier silicone; dimethylsilicone; SEC; rinse; SNPA; modified rates; derivatization.
Tatsuya Itoh1, Hiroshi Shimomura1, Yasuko Nishiyama1 and Shoji Imai2
1 Department of Chemistry, Joetsu University of Education, 1, Yamayashiki, Joetsu-shi, Niigata 943-0815(Received 7 April 2004, Accepted 4 April 2005)
The atomization of 0.2 ng Ag deposited on ascorbic acid pyrolysed at various temperatures was observed and the activation parameters were estimated. The mass of Ag and the pyrolysis conditions were selected to form droplets without any dispersion on a PG wall and active carbon. The kinetic order obtained indicated the formation of Ag aggregates on the active carbon at temperatures below 1560 K and the formation of individually dispersed atoms of Ag on that at temperatures over 1700 K. The degree of interaction between the Ag atom and an active site on the high temperature treated active carbon was increased, resulting from their greater interaction.
Keywords : atomic absorption spectrometry; silver; ascorbic acid; kinetic analysis; atomization mechanism.
Daijiro Kobori1
1 Organo Corporation, 1-4-9, Kawagishi, Toda-shi, Saitama 335-0015(Received 8 March 2005, Accepted 17 May 2005)
The state of water in anion-exchange resins of various anion forms was studied by differential scanning calorimetry (DSC). The amounts of non-freezing water molecules in both MR and Gel type resins were much the same in the order of F>OH>Cl>Br>I. The melting peak of the water in the Gel-type resins shifted to the high-temperature side in the order of I>Br>Cl>OH>F when the freezing water content of each ion form was equal. Moreover, the free water was detected in the I- form. These results indicated that the water molecules in the resins were strongly bound in the order of F>OH>Cl>Br>I.
Keywords : anion-exchange resins; DSC; non-freezing water; bound water.
Shiho Imai1, Youhei Kawanaka1, Ning Wang1 and Sun-Ja Yun1
1 The Institute of Basic Environmental Research, Environmental Control Center Co., Ltd., 323-1, Shimo-ongata, Hachioji-shi, Tokyo 192-0154(Received 24 February 2005, Accepted 18 May 2005)
A method has been developed for the determination of diphenylarsinic acid (DPAA) and phenylarsonic acid (PAA) in water samples by high-performance liquid chromatography with inductively coupled plasma mass spectrometry. DPAA and PAA could be separated from five arsenic species {As(III), As(V), monomethylarsonic acid, dimethylarsinic acid and trimetylarsine oxide} by using a column packed with hydrophilic-resin-based cation-exchange resin and a gradient elution with nitric acid-ammonium nitrate. Good linearity (coefficient of correlation≥0.998) of the calibration curve was obtained in the concentration range from 2 µg/l to 200 µg/l for DPAA and PAA. In addition, a solid-phase extraction method was developed to concentrate DPAA and PAA. The recoveries of DPAA and PAA from spiked groundwater samples were nearly 100% and the coefficients of variation were 2.6~2.9 %(n=5).
Keywords : diphenylarsinic acid; phenylarsonic acid; HPLC-ICP/MS; graphite carbon black cartridge; speciation.
Takahiro Yasuda1 and Mikio Kuzuya1
1 Department of Electronics and Information Engineering, College of Engineering, Chubu University, 1200, Matsumoto-cho, Kasugai-shi, Aichi 487-8501(Received 24 January 2005, Accepted 12 May 2005)
A quantitative analysis of trace lead in plastics was carried out with laser-induced plasma spectroscopy (LIPS). A Q-switched Nd:YAG laser (pulse energy, 90 mJ; pulse width, 10 ns; repletion rate, 10 Hz) was focused on plastic samples in an argon atmosphere, and the emission characteristics of the laser-induced plasma were investigated by changing the argon pressure from atmospheric pressure to 1 Torr. The experimental result showed that the emission intensity of the analysis line (Pb I 405.78 nm) was maximized at a pressure of around 10 Torr. The determination of trace lead in the standard plastic samples (polyethylene and polyvinyl chloride) was carried out in argon at 10 Torr. In the analysis of polyvinyl chloride, time-resolved spectroscopy was used to reduce the effect of the spectral interference with the matrix as well as the background. Linear calibration curves were obtained with detection limits of several tens ppm. The LIPS method was applied to industrial samples.
Keywords : laser-induced plasma spectroscopy; Nd:YAG laser; trace lead: plastic sample; argon gas.
Kazuhiko Fujiwara
Department of Materials-process & Applied Chemistry for Environments, Faculty of Engineering and Resource Science, Akita University, 1-1, Tegatagakuen-cho, Akita-shi, Akita 010-8502
(Awarded by Osaka University dated March 25, 2004)
Ion-association adsorption and interfacial aggregation of ionic-porphyrin at a liquid/liquid interface was investigated by means of two spectroscopic techniques; total-internal reflection (TIR) Raman microspectroscopy and second harmonic generation-circular dichroism (SHG-CD). In a TIR-Raman study, the electrostatic adsorption of meso-tetrakis(N-methylpyridyl)porphyrinato manganese(III) {Mn(TMPyP)5+} with dihexadecylphosphate (DHP) was analyzed. Polarized Raman spectra suggested that the average tilt angle of the porphyrin plane of the Mn(TMPyP)5+ molecule to the interface normal was 65° at the interface adsorbed with the DHP anion. The interfacial ion-association adsorption of Mn(TMPyP)5+ with DHP was analyzed by the Langmuir isotherm, and the adsorption parameters were obtained. On the other hand, interfacial adsorption and aggregation of Tetrakis-(4-sulfonatephenyl)porphyrin (TPPS) diacid, promoted by cetyltrimethylammonium(CTA+), was studied by SHG spectroscopy. The aggregation of TPPS at the heptane/water interface was elucidated by the linearly polarized SH spectrum compared with the transmission absorption spectrum of TPPS in aqueous solution. Also, the non-linear optical activity for the TPPS aggregate was also measured by means of SHG-CD and SHG-linear dichroism (SHG-LD). SHG-CD spectra indicated bisignate sign similar to that of the ordinary CD spectra for the aggregate. SHG-LD elucidated a magnetic-dipole contribution to some chiral structure of the TPPS aggregate.
(Received April 7, 2005)
Keywords : liquid/liquid interface; porphyrin; Raman microspectroscopy; second harmonic generation-circular dichroism.
Yoshinori Yamaguchi
Department of Chemistry, University of Michigan, 930 N. University ave, Ann Arbor, MI 48109-1055
(Awarded by University of Michigan at December 14, 2003)
The first three-dimensional (3-D) description of DNA electrophoretic migration is reported. The assumption of uniform probability of out-of-plane orientations, frequently made for DNA migration theory, has been verified. Also DNA gyration was clearly observed between the J forms and the original ball forms. The use of apparent two-dimensional (2-D) opening angles underestimated the true behavior. An extension of the Oana/Doi ellipsoidal approximation to DNA dimensions was used for quantitative descriptions. Although several limitations of the 3-D ellipsoid approximation are pointed out, it is sufficient for DNA migration image analysis. Statistics of DNA single molecule dynamics in DC electrophoresis systems were used to predict the ensemble electrophoretic migration times and overall band shapes. The migration times were predicted adequately and the asymmetric band shapes observed in electrophoresis were mirrored in the asymmetric migration time distributions of single molecules. Because the proper scaling relation is not known, it has not been possible to establish whether or not the data accurately predicts the bandwidth from single DNA molecule dynamics. Similar successes and limitations were observed for field inversion electrophoresis. Sample-size studies show that the range of the possibilities for DNA motions is limited, and much of it is explored rapidly. Scanning electron microscopy (SEM) and extended focus (EF) light microscopy were used for acquiring surface images of electrochemical surface enhanced Raman spectroscopy (SERS) substrates. Self-similarity was found from 30 µm to 100 nm, and was used to define the optimum fractal dimension for SERS activity, approximately 1.7. The activity thresholds found by both SEM and EF light microscopy were similar. Therefore, EF microscopy can be used to assess the quality of an electrode surface before it is irrevocably committed to an experiment.
(Received April 6, 2005)
Keywords : image analysis; capillary electrophoresis; DNA; scanning electron microscopy (SEM); electrophoretic band shape; surface enhanced Raman spectroscopy (SERS); DNA migration.
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