Vol. 52 No. 12
December, 2003
Takeshi Hirokawa1, Hikaru Okamoto1, Zhongqi Xu1 and Natsuki Ikuta1
1 Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1, Kagamiyama, Higashi-hiroshima-shi, Hiroshima 739-8527(Received 22 July 2003, Accepted 20 October 2003)
The concentration detection limit (DL) of capillary electrophoresis (CE) and microchip electrophoresis (MCE) is rather high due to geometrical restrictions of sample load. This drawback can be improved by applying high sensitivity detectors, such as a laser-induced fluorescence detector, and/or appropriate on-line preconcentration. Since the latter approach is useful even when using conventional instruments equipped with a UV detector, several on-line preconcentration methods have been devised. This paper emphasizes the effectiveness of transient isotachophoresis (tITP) and tITP with electrokinetic injection of sample (electrokinetic supercharging). Such advancing strategies for improving DL in CE and MCE were illustrated by applications to several metal cations and anions in seawater and biopolymers, such as DNA fragments and SDS-proteins. Under the optimized operational conditions, DLs of CE reached a sub-ppb level comparable with those of IC and ICP-AES for anions and metal cations, respectively. The DL of MCE was ca. 0.02 µg/ml for DNA fragments and ca. 0.3 µg/ml for SDS-proteins, which are 10~40 times better than of the conventional methods.
Keywords : Capillary electrophoresis; Microchip electrophoresis; On-line preconcentration; Transient isotachophoresis; Electrokinetic supercharging.
Makoto Tsunoda1 and Kazuhiro Imai1,2
1 Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033(Received 14 July 2003, Accepted 22 August 2003)
We have developed the highly selective and sensitive determination methods for catecholamines (and their 3-O-methyl metabolites). Selectivity was achieved with an in-line extraction of amines using a cation exchange precolumn and fluorogenic derivatization with ethylenediamine, which reacts selectively with catechol moiety. Sensitivity was achieved with peroxyoxalate chemiluminescence reaction detection. The use of semi-micro column enabled to obtain more sensitivity and measure only 10 µl of a mouse plasma. The developed methods were applicable to the clarification of the roles of catecholamines and their 3-O-methyl metabolites in blood pressure regulation.
Keywords : catecholamine; HPLC; chemiluminescence; catechol-O-methyltransferase; semi-micro column.
Shizuko Hirata1, Tasuku Kajiya2, Masato Aihara2, Kazuto Honda3 and Osamu Shikino3
1 National Institute of Advanced Industrial Science and Technology, 2-2-2, Hiro-suehiro, Kure-shi, Hiroshima 737-0197(Received 16 July 2003, Accepted 30 October 2003)
An automated low-pressure flow-analysis method with on-line column preconcentration/inductively coupled plasma mass spectrometry (ICPMS) was developed for the determination of trace metals and rare earth elements (REEs) in seawater. A homemade column of a commercially available imminodiacetic functional group resin, Muromac A-1, was used to separate and concentrate trace metals (Al, V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb and U) or REEs (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) from seawater. Sample solutions adjusted to the optimized pH passed through the column, after washing the column with water. The adsorbed elements were subsequently eluted into the plasma with 0.7 M nitric acid. One sample could be analyzed in 7 min using a 7 ml sample. The proposed method was verified by the analysis of two reference standard materials of seawater, CASS-3 and NASS-4. This method was applied to the determination of trace metals and REEs in seawater of Hiroshima Bay, the Seto Inland Sea, Japan.
Keywords : inductively coupled plasma mass spectrometry; Muromac A-1; trace elements; seawater; on-line column preconcentration.
Hiroshi Ozawa1, Zilin Chen2, Katsuhiko Kawata1, Tatsuro Nakagama1, Katsumi Uchiyama1 and Toshiyuki Hobo1
1 Department of Applied Chemistry, Graduate School of Engineering, Tokyo Metropolitan University, 1-1, Minamiohsawa, Hachioji-shi, Tokyo 192-0397(Received 18 July 2003, Accepted 20 September 2003)
We describe the capillary electrochromatographic behaviors of dansyl amino acids on a γ-cyclodextrin-immobilized monolithic silica column. The changes in the enantio-selectivity and retention behavior, were investigated when organic modifiers, like methanol, actonitrile and tetrahydrofuran were added in the mobile phases. It was found that the enantioselectivity could be manipulated by the addition of moderate organic solvents. The effect of the temperature on the separation behavior was also examined by a thermodynamic analysis. It was shown that a relatively low temperature under enthalpic control benefits the enantio-separation. Further, the relationship between the hydrophobicity of the analytes and the retention behavior was investigated.
Keywords : capillary electrochromatography; monolithic column; sol-gel process; chiral separation; cyclodextrin; dansyl amino acids.
Hideyuki Yoshida1, Kayoko Horita1, Kenichiro Todoroki1, Hitoshi Nohta1 and Masatoshi Yamaguchi1
1 Faculty of Pharmaceutical Sciences, Fukuoka University, Nanakuma, Johnan-ku, Fukuoka-shi, Fukuoka 814-0180(Received 11 July 2003, Accepted 1 August 2003)
A highly selective fluorimetric determination method for acidic amino acids, glutamic acid, aspartic acid and N-methyl-D-aspartic acid (NMDA), has been developed. This method is based on an intramolecular excimer-forming fluorescence derivatization with a pyrene reagent, 4-(1-pyrene)butyric acid hydrazide (PBH), followed by reversed-phase high-performance liquid chromatography (HPLC). Aspartic acid and NMDA, containing two carboxyl moieties in a molecule, were converted to the corresponding dipyrene-labeled derivatives by a reaction with PBH in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and pyridine. Glutamic acid was PBH-derivatized after the amine-protection with orthophthalaldehyde. These derivatives afforded intramolecular excimer fluorescence (440~540 nm), which could clearly be discriminated from the normal fluorescence (360~420 nm) emitted from PBH and monopyrene-labeled derivatives of monocarboxylic acids. The PBH derivatives of acidic amino acids could be separated by reversed-phase HPLC on an ODS column with isocratic elution using aqueous 67%(v/v) acetonitrile as the mobile phase. The detection limits (signal-to-noise ratio=3) for glutamic acid, aspartic acid and NMDA were 21, 32 and 460 fmol, respectively, for a 20 µl injection.
Keywords : acidic amino acids; high-performance liquid chromatography; excimer fluorescence; 4-(1-pyrene)butyric acid hydrazide; neurotransmitter.
Takashi Yasui1, Takashi Ohnishi1, Yoshiyuki Mizuno1, Nayumi Ohata2 and Hiromichi Yamada1
1 Shikumi College, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya-shi, Aichi 466-8555(Received 24 July 2003, Accepted 17 September 2003)
The retention properties of mono-nitrated 2-(2-pyridylazo)-1-naphthol (xN-a-PAN, x=3 or 5), in which a nitro group was involved at the 3- or 5-position of each pyridine ring, and their metal complexes in reversed-phase high-performance liquid chromatography (RP-HPLC) were investigated. The retention time for the neutral complexes became longer in the nitro derivatives systems than in the a-PAN system. The bulkiness of the nitro group strongly influences the retention time for each metal complex. The peaks for cobalt(II) complexes as well as that for cobalt(III) complexes were observed in the N-a-PAN systems. Moreover, only in the 3N-a-PAN system, the retention time of the reagent itself was observed to be shorter than that of the cationic Co(III) complex. The acid dissociation constant, the partition constant, and the crystal structure of 3N-a-PAN suggested that the neutral form exists as a hydrazone (keto) tautomer.
Keywords : 2-(3-nitro-2-pyridylazo)-1-naphthol (3N-a-PAN); acid dissociation constant; partition constant; crystal structure; azo-hydrazone tautomerism.
Michio Zenki1, Kazuyoshi Minamisawa1 and Takashi Yokoyama1
1 Department of Chemistry, Faculty of Science, Okayama University of Science, 1-1, Ridai-cho, Okayama-shi, Okayama 700-0005(Received 11 July 2003, Accepted 7 August 2003)
The spectrophotometric determination of Cu(II) with 4-methyl-5-[(sulfomethyl)amino]-2-(2-thiazolylazo)benzoic acid(TAMSMB) was carried out by a cyclic flow-injection analysis. A cation -exchange column for on-line regeneration of the main reagent was incorporated in this FIA system, allowing a repetitive determination of Cu(II). A solution of 5×10-5 M TAMSMB in 0.1 M acetate buffer (pH 3.7) in a single reservoir (50 ml) was continuously circulated at a constant flow rate of 1.25 ml min-1. Into the stream, an aliquot (20 µl) of a sample containing Cu2+ was quickly injected by means of a 6-way valve. The complex formed was monitored spectrophotometrically at 585 nm in the flow system. Then, the stream passed through a cation-exchange column, which was introduced after the flow-through cell. A successful ligand-exchange reaction of Cu2+ between the TAMSMB reagent and a cation-exchanger, as well as a simultaneous regeneration of the free reagent took place. The stream then returned to the reservoir. The regeneration and recycling of the TAMSMB reagent allowed as many as 500 repetitive determinations of 1.5 µg l-1 Cu2+ solutions with the same 50 ml circulating solution.
Keywords : cyclic-FIA; regeneration of a reagent solution; repetitive determination of copper(II); 4-methyl-5-sulfomethylamino-2-(2-thiazolylazo)benzoic acid(TAMSMB).
Motoko Koitabashi1, Akira Kotani1 and Fumiyo Kusu1
1 School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1, Horinouchi, Hachioji-shi, Tokyo 192-0392(Received 16 July 2003, Accepted 22 August 2003)
A novel method for determining lidocaine using a flow-injection analysis system with electrochemical detection (FIA-ECD) has been developed. The detection was based on the voltammetric oxidation prepeak of α-tocopherol, due to lidocaine, where the prepeak current was proportional to the concentration of lidocaine. Using FIA-ECD, the peak current height, which was proportional to the amount of lidocaine, ranged from 11.7 ng to 585 ng (r=0.998). Standard lidocaine at 117 ng was determined ten times with a relative standard deviation (RSD) of 1.9%. The detection limit (S/N=3) was 11.7 ng. To determine the purity of lidocaine in drugs listed in the Japanese Pharmacopoeia, the conventional titration method and the present method were used. Both analytical results were essentially identical. The presented method is useful for the determination of lidocaine, because it requires only one hundredth of the amount of lidocaine and one twentieth of the measuring time, and produces less waste compared to the titration method.
Keywords : flow-injection analysis; electrochemical detection; α-tocopherol; lidocaine.
Reo Shoji1, Toshifumi Takeuchi2, Hiroaki Suzuki3 and Izumi Kubo1
1 Faculty of Engineering, Soka University, 1-236, Tangi, Hachioji-shi, Tokyo 192-8577(Received 17 July 2003, Accepted 22 August 2003)
Atrazine has been used as a herbicide, and acts as an endocrine-disrupting chemical. We have been studying the development of an electrochemical sensing system for atrazine based on its reductive current. In order to give selectivity to the sensing system, a gold electrode of chip was modified with a nano chemical receptor as a recognition element of atrazine utilizing a molecular imprinting technique. The nano chemical receptor is nano meter in its size, which has a specific binding site of a template molecule. We propose an atrazine sensor chip modified with nano chemical receptors. Preparation of nano chemical receptor chip was performed by the UV irradiated polymerization of a cocktail composed from a template molecule of atrazine, MAA, EDMA and AIBN dissolved in DMF on the surface of the gold chip. The gold surface was modified by an allyl group so as to immobilize the receptor layer on the surface. After preparing nano chemical receptors on the chip, atrazine was removed. A measurement of atrazine was performed by cyclic voltammetry. Cathodic current of atrazine was observed at negative potentials lower than -500 mV vs. Ag/AgCl. The reductive current showed a dependence on the concentration of atrazine in the range of 1-10 µM with the chip A (1.5×13 mm). In order to develop miniaturized sensor, chip B with an area of 1.8×0.6 mm was used. With the use of chip B, atrazine could be determined as well as with chip A. The thickness of nano chemical receptor layer was controlled by spin-coating. By rotating at 800 rpm, the thickness of the layer was controlled to 35±3.5 µm, whereas without spinning it was 65±12.1 µm. A chip with thinner layer gave slightly larger responses with a smaller standard deviation. By using chip B with a controlled receptor layer, the detection limit was as low as 50 nM (10.8 ppb).
Keywords : atrazine; molecular imprinting; sensor; electrochemistry; nano.
Minoru Okumura1, Kaoru Fujinaga1, Yasushi Seike1, Mika Nagata1 and Shuji Matsuo1
1 Interdisciplinary Faculty of Science and Engineering, Shimane University, 1060, Nishikawatsu-cho, Matsue-shi, Shimane 690-8504(Received 14 July 2003, Accepted 1 October 2003)
A simple in situ preconcentration method using solid-phase extraction for the simultaneous determination of arsenic(III) (arsenite)and arsenic(V) (arsenate) in environmental water samples has been developed, followed by hydride generation-atomic absorption spectrometry. This method is based on the simultaneous collection of arsenic(III) and arsenic(V) and their successive elution from a small column packed with a zirconium-loaded sorbent. A water sample was taken into a graduated syringe to prevent the oxidation of arsenic(III) to arsenic(V) by air. The water sample (pH 4.5) was passed through a small column to collect arsenic(III) and arsenic(V) onto it. The retained arsenic(III) and arsenic(V) were quantitatively eluted with 0.5 mol/l hydrochloric acid and then a 0.5 mol/l sodium hydoxide solution, respectively. The proposed method is applicable to brackish and sea-water samples as well as fresh-water samples.
Keywords : determination of arsenic(III) and arsenic(V); arsenite; arsenate; preconcentration; solid phase extraction.
Yuji Sano1, Tomomi Kato1, Isoshi Nukatsuka1 and Kunio Ohzeki1
1 Department of Materials Science and Technology, Faculty of Science and Technology, Hirosaki University, 3, Bunkyocho, Hirosaki-shi, Aomori 036-8561(Received 22 July 2003, Accepted 3 October 2003)
A new method for the indirect spectrophotometic determination of arsenic was developed. This method is based on the extraction of arsenic(III) from a solution of pH 1.5 on a finely divided anion-exchange resin as a complex with ammonium pyrrolidinedithiocarbamate(APDC), separation of the resin fixing the As(III)-APDC complex from the bulk solution on a membrane filter, re-dispersion of the resin in a solution containing copper(II) and conversion of a coloreless As(III)-APDC complex to a yellow Cu(II)-APDC complex, collection of the rsin on a membrane filter and measurement of the absorbance of the resulting Cu(II)-APDC complex in the resin phase by a spectrophotometer or a dennsitometer. The effects of interfering ions were successfully suppressed with the combined use of diethyldithiocarbamate (DDTC) and EDTA. The method was applied to a standard river water sample. Good results were obtained for the detemination of arsenic(III, V) at the ppb level in 40 ml of the sample.
Keywords : arsenic(III); total arsenic(III, V); arsenic(III)-APDC; copper(II)-APDC; finely divided ion-exchange resin; resin phase spectrophotometry.
Akiko Nakagawa-izumi1 and Ken-ichi Kuroda1
1 Institute of Agricultural and Forest Engineering, University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi, Ibaraki 305-8572(Received 22 July 2003, Accepted 24 October 2003)
Pyrolysis-gas chromatography in the presence of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), BSTFA/Py-GC, was developed for analyzing the end groups of cinnamyl alcohols and cinnamyl aldehydes in lignin simultaneously, using a dry-iced cooled sample-introduction apparatus for a Curie-point pyrolyzer suitable for the analysis of thermal labile samples. BSTFA/Py-GC of a dehydrogenative polymer (M-DHP), enzymatically prepared from a mixture of coniferyl alcohol and coniferyl aldehyde (1:1 mol/mol), and a Japanese cedar (Cryptomeria japonica D. Don) wood, were performed at 590°C for 4 s. BSTFA/Py-GC of M-DHP provided trimethylsilyl (TMS) ethers of coniferyl alcohol and coniferyl aldehyde as the main products, along with vanillin TMS ether. The cedar wood provided a large level of coniferyl alcohol diTMS ether and a trace level of coniferyl aldehyde TMS ether, suggesting that the cedar native lignin contains a very small abundance of the pyrolytic sources, producing coniferyl aldehyde. A comparison of the pyrolytic efficiencies producing coniferyl alcohols and aldehydes among different pyrolysis methods showed the high sensitivity of BSTFA/Py. Unlike BSTFA/Py-GC, capable of analyzing both end groups, the pyrolysis of M-DHP in the presence of tetramethylammonium hydroxide provided coniferyl alcohol dimethyl ether and no coniferyl aldehyde methyl ether, suggesting that this method provides useful information on cinnamyl alcohol end groups, but no information on cinnamyl aldehyde end groups.
Keywords : lignin; coniferyl alcohol end groups; coniferyl aldehyde end groups; pyrolysis-gas chromatography(/mass spectrometry); trimethylsilylation.
Yoshiyuki Watabe1, Ken Hosoya1, Nobuo Tanaka1, Takuya Kondo2, Hiroe Imai2 and Masatoshi Morita2
1 Department of Polymer Science, Kyoto Institute of Technology, Matsugasaki, Goshokaido-machi, Sakyo-ku, Kyoto-shi, Kyoto 606-8585(Received 4 July 2003, Accepted 6 August 2003)
A possible endocrine disrupter, bisphenol A (BPA) in environmental water, was analyzed using conventional HPLC coupled with an electrochemical detector (ECD). The ECD-HPLC method realized a much easier and reliable pre-treatment process compared with the usual GC/MS method. In this study, we utilized a column-switching system for the analysis of BPA in environmental water. We also utilized a commercial membrane for the concentration of environmental water. The quantification limit observed in this study was 5 ng/l (ppt). The column switching system utilizing high-pressure 6 port valves realized 0.7 ppt as the detection limit, and the reproducibility observed using a 1 ppt standard sample of BPA was 2.7% (RSD). In addition, although BPA was found to somehow be decomposed in environmental water, we found a storage method of BPA.
Keywords : electrochemical detection; HPLC; bisphenol A; natural water; high sensitivity.
Mikaru Ikedo1,2, Masanobu Mori2, Qun Xu2, Hiroshi Taoda2, Shinji Sato3, Wenzhi Hu4 and Kazuhiko Tanaka1,2
1 Graduate School of Chubu University, 1200, Matsumoto-cho, Kasugai-shi, Aichi 487-0027(Received 18 July 2003, Accepted 1 September 2003)
A simple, selective, and sensitive method for the simultaneous determination of anions, such as sulfate, nitrate, and chloride ions, and cations, such as sodium, ammonium, potassium, magnesium, and calcium ions, in aging water extracted from a raw material of ceramic glaze was investigated using ion-exclusion/cation-exchange chromatography with conductimetric detection on a weakly acidic cation-exchange resin column (Tosoh TSKgel Super IC-A/C) and a tartaric acid/crown ether eluent. With the weak-acid eluent(tartaric acid), both anions and cations were separated simultaneously and selectively, based on the ion-exclusion and cations-exchange mechanism. Owing to the presence of H+ ions in the tartaric acid eluent, the conductimetric detector response was positive for the anions and negative for the cations. Using a 7 mM tartaric acid/3.5 mM 18-crown-6 at 1 ml/min, a good simultaneous separation and detection was achieved in about 7 min. This method was successfully applied for the simultaneous determination of several anions and cations in aging water samples extracted from the raw material of a ceramic glaze.
Keywords : Ceramic glaze; Ion-exclusion/cation-exchange chromatography; Simultaneous determination; Inorganic anions and cations.
Tetsuya Tachibe1, Shoji Kozuka1, Yuji Yamada1, Mitsuhiro Tomita1 and Miyuki Takenaka1
1 Corporate Research and Development Center, Toshiba Corporation, 1, Komukai, Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa 212-8582(Received 11 August 2003, Accepted 17 October 2003)
A method of trace arsenic determination for silicon wafers by a wet chemical technique in conjunction with cation-exchange separation/ICP-MS has been developed. It was found that 50 to 90% of the arsenic extant in silicon wafers was vaporized by the normal decomposition method using a HF/HNO3 solution. The addition of a 6% KMnO4 solution was very effective in preventing arsenic vaporization during the decomposition process; however, K and Mn matrices also remained in the solution. In order to reject matrix elements during the ICP-MS measurement, K and Mn were separated from As by cation-exchange separation. The trace arsenic concentration was determined with both high recovery and accuracy using this method. The relative standard deviation was 1.2 to 1.9%.
Keywords : silicon wafer; arsenic; ion exchange separation; ICP-MS.
Syouhei Nishihama1, Kazuharu Yoshizuka1, Louis Scampavia2 and Jaromir Ruzicka2
1 Faculty of Environmental Engineering, The University of Kitakyushu, 1-1, Hibikino, Kitakyushu-shi, Fukuoka 808-0135(Received 16 July 2003, Accepted 10 September 2003)
A sequential injection analysis (SIA) system with an integrated lab-on-valve manifold has been investigated concerning a spectrophotometric chloride ion assay. By optimizing the procedure parameters of SIA, the concentration of chloride ion can be detected to 45.0 ppb. The assay for higher concentrations of up to 100 ppm was achieved by optimally changing the manipulation conditions and the protocol. Futher, over a 3-decade concentration range of chloride ion can be analyzed quantitatively. The drastic reduction of reagent consumption as the largest advantage of downsizing can also be achieved using the lab-on-valve SIA system. The method described here serves as a typical template for downsizing other assays using the micro total analysis system (µ-TAS).
Keywords : sequential injection analysis, lab-on-valve, chloride ion assay.
Takashi Kaneta1, Miki Nishida1 and Totaro Imasaka1
1 Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka-shi, Fukuoka 812-8581(Received 18 July 2003, Accepted 1 September 2003)
Hadamard transform capillary electrophoresis, which is a sensitive detection method using multiple sample injection, was applied to the separation of glutamic acid enantiomers labeled with fluorescein isothiocyanate (FITC). A capillary was filled with a sample solution containing FITC-labeled D,L-glutamic acids, cyclodextrin, and buffer components. The sample was injected by an optically gated sample injection method, in which an intense laser beam was focused onto the capillary to convert fluorescent analyte ions to nonfluorescent ones by photodegradation. To form analyte plug, a shutter placed in the pathway of the laser beam was closed for a constant time period. In the presence of cyclodextrin, enatiomers of FITC-labeled glutamic acid could be injected by the optically gated sample injection method. Two cyclodextrins, β- and γ-cyclodextrins, were employed as chiral selectors in the capillary electrophoretic separations. For the separation of FITC-labeled glutamic acid enantiomers, γ-cyclodextrin shows a better resolution than β-cyclodextrin. The optimum concentration of γ-cyclodextrin was found to be 10 mM. Multiple sample injection was accomplished by closing or opening the shutter according to a sequence based on a Hadamard matrix. When the resulting electropherogram was transformed by the inverse Hadamard matrix, The S/N ratio in the transformed result was enhanced with no degradation in the resolution, compared to that in the electropherogram obtained by a single injection method. As a result, Hadamard transform capillary electrophoresis allows a significant improvement in the S/N ratios for FITC-labeled glutamic acid enantiomers. Therefore, the present method will be applicable to the separation and sensitive detection of enantiomers labeled with FITC.
Keywords : capillary electrophoresis; Hadamard transform; multiple injection; enantiomer; separation.
Takahiro Umeno1, Yasuaki Okamoto1 and Terufumi Fujiwara1
1 Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1, Kagamiyama, Higashihiroshima-shi, Hiroshima 739-8526(Received 17 July 2003, Accepted 13 September 2003)
A continuous on-line mixing of luminol, hydrogen peroxide, and copper(II) ion produced a strong and steady chemiluminescence. Upon mixing of an amino acid into a flow of copper(II) ion, the formation of the copper(II) complex with the amino acid caused a decrease in the chemiluminescence intensity. This quenching phenomenon was applied to the determination of amino acids which were separated by a capillary electrophoresis coupled to the chemiluminescence detection. With this system, detection limit ranges of 0.65~3.4 µmol dm-3 were obtained with linear response ranges from the detection limits to the upper limits of 83~130 µmol dm-3 for several amino acids.
Keywords : capillary electrophoresis; amino acid; chemiluminescence; quantitative analysis.
Tadao Furumoto1, Takao Fukumoto1 and Hitoshi Watarai1
1 Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama-machi, Toyonaka-shi, Osaka 560-0043(Received 28 July 2003, Accepted 23 October 2003)
The TOF/MS detection of nucleobases and nucleosides in capillary electrophoresis using a silica capillary combined with a stainless-steel electrospray ionization interface was studied under acidic conditions. The results showed that the nucleobases were migrated and detected as protonated species, while the nucleosides were detected by TOF/MS as the original nucleosides and the nucleobases fragment formed by collision-induced dissociation, after the migration of nucleosides as protonated species.
Keywords : TOF/MS; capillary electrophoresis; nucleobases; nucleosides.
Jinghua Zhang1, Naoki Nishimura2, Shinji Sakata2, Mika Ozaki1, Kazuyoshi Takeda3 and Sunao Yamazaki1
1 Faculty of Environmental Studies, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki-shi, Nagasaki 852-8521(Received 6 August 2003, Accepted 3 October 2003)
Varieties of barley were cultured with and without drought stress and an osmoregulatory cellular component, glycine betaine, was determined by capillary electrophoresis. The relation between the betaine levels and stress-tolerance in the varieties was surveyed. The salt stress-tolerant and -sensitive varieties were well discriminated by the betaine levels in the seedlings of barley cultured under stressed and unstressed conditions. Also, the betaine levels could discriminate between African and Japanese varieties, presumably due to the climate difference between the two areas. It was found that glycine betaine is a good candidate as a probe in selecting environmental stress-tolerant plant species.
Keywords : barley; capillary electrophoresis; drought stress; glycine betaine; salt stress.
Tamio Seko1, Koichi Usukura2 and Nobuhiko Onda2
1 PerkinElmer Japan Co. Ltd., 5-3 Toyotsu-cho, Suita-shi, Osaka 564-0051(Received 22 July 2003, Accepted 28 September 2003)
A sorbent for the thermal desorption-GC/MS to analyze volatile organic compounds (VOC) and phthalic acid esters(PAE) in air was selected and characterized. The combination of commercial sorbents of TenaxTA and Carboxen1000 packed in sequence into a desorption tube was applied to compounds with a wide boiling point, such as ethanol, through diethyl hexyl phthalate (DEHP). The analytical results were confirmed for the linearity of the calibration over a range of 10~500 ng with a correlation coefficient of 0.999~1.000, and also for a repeatability of 1.5~2.0% to VOC and 2.2~6.2% to PAE. The detection limit was found to be 0.07~2.67 ng for 3 liters, or a detection limit of 0.02 mg/m3 for toluene. With the prepared tube, of sampled air a simultaneous analysis of VOC and PAE in indoor air and in the emitted gas from the building materials was performed.
Keywords : VOC; phthalic acid ester; thermal desorption-GC/MS; TenaxTA/Carboxen1000; indoor air.
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