Publications (from 2001 to 2011)

• Another approach toward over 100000-fold sensitivity increase in capillary electrophoresis: Electrokinetic supercharging with optimized sample injection, Zhongqi Xu, K. Nakamura, A.R. Timerbaev, T. Hirokawa, Anal.Chem. 83, 398-401 (2011).
  
• Electrokinetic supercharging with a system-induced terminator and an optimized capillary versus electrode configuration for parts-per-trillion detection of rare earth elements in CZE, Zhongqi Xu, K. Kawahito, X. Ye, A.R. Timerbaev, T. Hirokawa, Electrophoresis (2011) in press.
  
• Band-broadening suppressed effect in long turned geometry channel and high-sensitive analysis of DNA sample by using floating electrokinetic supercharging on a microchip
  Zhongqi Xu, Kenji Murata, Akihiro Arai and Takeshi Hirokawa, BIOMICROFLUIDICS 4, 014108 (2010) (URL: http://link.aip.org/link/?BMF/4/014108).
  
• Focusing of anionic micelles using sample induced transient isotachophoresis: Computer simulation and experimental verification in MEKC
  Lidia S. Foteeva, Zhuo Huang, Andrei R. Timerbaev, Takeshi Hirokawa, J. Sep. Sci., 33, 637-642 (2010).
  
• Sensitive profiling of biogenic amines in urine using CE with transient isotachophoretic preconcentration
  Zhongqi Xu, Jiro Okada, Andrei R. Timerbaev, Takeshi Hirokawa, J. Sep. Sci., 32, 4143-4147 (2009).
  
• Electrokinetic sample injection for high-sensitivity capillary zone electrophoresis (part 2): Improving the quantitative repeatability and application of EKS-CZE to the detection of atmospheric electrolytes
  Zhongqi Xu, Eiji Koshimidzu, Takeshi Hirokawa, Electrophoresis, 30, 3534-3539 (2009).
  
• Iodine and iodine species in seawater -Speciation, distribution and dynamics-, Chapter 9, COMPREHENSIVE HANDBOOK OF IODINE (Elsevier)
  Kazuaki Ito and Takeshi Hirokawa (2009).
  
• Preconcentration and separation of DNA fragments based on microchip electrophoresis
  XU Zhongqi, HIROKAWA Takeshi, Chinese Journal of Chromatography, 27, 102-106 (2009)
  
• High-sensitive analysis of DNA fragments by capillary gel electrophoresis using transient isotachophoresis preconcentration and fluorescence detection
  Zhongqi Xu, Toshiaki Esumi, Natsuki Ikuta, Takeshi Hirokawa, J. Chromatogr. A, 1216, 3602-3605 (2009)
  
• High-sensitivity capillary and microchip electrophoresis using electrokinetic supercharging preconcentration: Insight into the stacking mechanism via computer modeling
  Zhongqi Xu, Andrei R. Timerbaev, Takeshi Hirokawa, J. Chromatogr. A, 1216, 660-670 (2009)
  
• キャピラリー電気泳動法およびマイクロチップ電気泳動法のElectrokinetic supercharging:スタッキング機構と小イオンから生体高分子までの高感度分析への応用
  徐　中其、伊藤一明、荒井昭博、廣川　健、生物物理化学、52、117-122（2008）
  
• Characterization of Calcium Carbonate Polymorphs with Ca K Edge X-Ray Absorption Fine Structure Spectroscopy
  Shinjiro Hayakawa, Yuki Hajima, Shan Qiao, Hirofumi Namatame, Takeshi Hirokawa, Anal. Sci., 24, 835-837 (2008)
  
• Sensitive determination of anions in saliva using capillary electrophoresis after transient isotachophoretic preconcentration
  Zhongqi Xu, Takayuki Doi, Andrei R. Timerbaev, Takeshi Hirokawa, Talanta,77, 278-281 (2008)
  
• Electrokinetic sample injection for high-sensitivity capillary zone electrophoresis (part 1): Effects of electrode configuration and setting
  Takeshi Hirokawa, Eiji Koshimidzu, Zhongqi Xu, Electrophoresis, 29, 3786-3793 (2008)
  
• Study of a novel sample injection method (floating electrokinetic supercharging) for high-performance microchip electrophoresis of DNA fragments
  Takeshi Hirokawa, Yoichi Takayama, Akihiro Arai, Zhongqi Xu, Electrophoresis, 29, 1829-1835 (2008)
  
• Simultaneous monitoring of inorganic cations, amines and amino acids in human sweat by capillary electrophoresis
  Takeshi Hirokawa, Hikaru Okamoto, Yoshinori Gosyo, Takao Tsuda,Andrei R. Timerbaev, Anal. Chim. Acta 581, 83-88 (2007)
  
• Determination of cisplatin and its hydrolytic metabolite in human serum by capillary electrophoresis techniques
  Zhuo Huang, Andrei R. Timerbaev, Bernhard K. Keppler, Takeshi Hirokawa, J.Chromatogr. A 1106, 75-79 (2006)
  
• Recent advances of transient isotachophoresis-capillary electrophoresis in the analysis of small ions from high-conductivity matrices
  Andrei R. Timerbaev, Takeshi Hirokawa, Electrophoresis 27 (1), 323-340 (2006)
  
• Single particle analysis for chemical characterization of atmospheric aerosols application of x-ray microprobe system and double thin film method
  SUSUMU TOHNO, CHANG-JIN MA, SHINJIRO HAYAKAWA, SATOSHI YAMASAKI and MIKIO KASAHARA, Environmental Monitoring and Assessment 120, 575-584 (2006)
  
• Elemental Distribution in Individual Rain Droplets Determined by a Combination of the Replication Method and the Synchrotron Radiation X-ray Fluorescence Microprobe Technique
  C.-J. MA, S. TOHNO, M. KASAHARA, and S. HAYAKAWA, Anal. Sci. 22,415-420 (2006)
  
• Impact of reservoir potentials on the analyte behavior in microchip electrophoresis estimated by computer simulation and experimental validation for DNA fragments
  Zhongqi Xu, Y. Nakamura, Takeshi Hirokawa, Electrophoresis 28, 383-390 (2005)
  
• Simultaneous determination of metal ions, amino acids, and other small biogenic molecules in human serum by capillary zone electrophoresis with transient isotachophoretic preconcentration
  Hikaru Okamoto, Andrei R. Timerbaev, Takeshi Hirokawa, Journal of Separation Science 28, 522-528 (2005)
  
• Ion chromatography for determination of nitrite and nitrate in seawater using monolithic ODS columns
  Kazuaki Ito, Yohichi Takayama, Nobuyuki Makabe, Ryo Mitsui, Takeshi Hirokawa, J. Chromatogr. A 1083, 63-67 (2005)
  
• Sensitive monitoring of iodine species in sea water using capillary electrophoresis: vertical profiles of dissolved iodine in the Pacific Ocean
  Zhuo Huang, Kazuaki Ito, Isamu Morita, Kuriko Yokota, Keiichi Fukushi, Andrei R. Timerbaev, Shuichi Watanabe, Takeshi Hirokawa, J. Environ. Monit 7, 804-808(2005)
  
• キャピラリー電気泳動法により得られるエレクトロフェログラムの標準化
  廣川健,育田夏樹, 臨床検査49, 949-959(2005)
  
• Investigation of Individual Micrometer-Size Kosa Particle with On-Site Combination of Electron Microscope and Synchrotron X-Ray Microscope
  Y. TANAKA, Y. TANIGUCHI, D. TANAKA, M. TOYODA, H. ISHII, T. TANABE, Y. TERADA, S. HAYAKAWA, J. KAWAI, Anal. Sci. 21, 839-843 (2005)
  
• High-sensitivity capillary electrophoresis determination of inorganic anions in serum and urine using on-line preconcentration by transient isotachophoresis
  Takeshi Hirokawa, Masato Yoshioka, Hikaru Okamoto, Andrei R. Timerbaev and Gottfried Blaschke, J. Chromatogr. B 811, 165-170 (2004)
  
• Further research on iodine speciation in seawater by capillary zone electrophoresis with isotachophoresis Preconcentration
  Zhuo Huang, Kazuaki Ito, Takeshi Hirokawa, J. Chromatogr. A 1055, 229-234 (2004)
  
• Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column
  Kazuaki Ito, Yohichi Takayama, Mikaru Ikedo, Masanobu Mori, Hiroshi Taoda, Qun Xu, Wenzhi Hu, Hiroshi Sunahara,Tsuneo Hayashi, Shinji Sato, Takeshi Hirokawa and Kazuhiko Tanaka,J.Chromatogr. A 1039, 141-145(2004)
  
• Speciation studies by capillary electrophoresis - simultaneous determination of iodide and iodate in seawater
  Zhuo Huang, Kazuaki Ito, Andrei R. Timerbaev, Takeshi Hirokawa, Anal. Bioanal. Chem. 378, 1836-1841 (2004)
  
• Optimization of the electrokinetic supercharging for high-sensitivity microchip gel electrophoresis on a cross-geometry microchip
  Zhongqi Xu and Takeshi Hirokawa, Electrophoresis 25, 2357-2362(2004)
  
• Performance of electrokinetic supercharging for high-sensitivity detection of DNA fragments in chip gel electrophoresis
  Zhongqi Xu, Tsutomu Nishine, Akihiro Arai, Takeshi Hirokawa,Electrophoresis 25, 3875-3881(2004)
  
• 微小ビーム強度モニターの開発とマイクロビームX線分析への応用
  早川　慎二郎, 鈴木　基寛, 廣川　健, Adv. X-ray Chem. Anal. Japan 34, 133-141 (2003)
  
• Application of electrokinetic supercharging capillary zone electrophoresis to rare-earth ore samples
  Hikaru Okamoto and Takeshi Hirokawa, J.Chromatogr. A 990, 335-341 (2003)
  
• Trace ion analysis of sea-water by capillary electrophoresis: determination of strontium and lithium pre-concentrated by transient isotachophoresis
  Hikaru Okamoto, Yasuaki Okamoto, Takeshi Hirokawa and Andrei R. Timerbaev, Analyst 128, 1439 - 1442 (2003)
  
• Determination of trace iodide in seawater by capillary electrophoresis following transient isotachophoretic preconcentration Comparison with ion chromatography
  Kazuaki Ito, Teppei Ichihara, Huang Zhuo, K Kumamoto, Andrei R. Timerbaev, Takeshi Hirokawa, Anal. Chim. Acta 497, 67-74 (2003)
  
• Mechanistic Study on Analyte Focusing by Dynamic pH Junctionin Capillary Electrophoresis Using Computer Simulation
  Jong-Bok Kim, Philip Britz-McKibbin, Takeshi Hirokawa and Shigeru Terabe, Anal. Chem. 75, 3986-3993 (2003)
  
• Trace ion analysis of seawater by capillary electrophoresis: determination of iodide using transient isotachophoretic preconcentration
  Takeshi Hirokawa, Teppei Ichihara, Kazuaki Ito, Andrei R. Timerbaev, Electrophoresis 24, 2328-2334 (2003)
  
• Specific analyte-electrolyte additive interaction in transient isotachophoresis-capillary electrophoresis
  Takeshi Hirokawa, Teppei Ichihara, Andrei R. Timerbae, J.Chromatogr 993, 205-209 (2003)
  
• High-sensitive capillary zone electrophoresis analysis by electrokinetic injection with transient isotachophoretic preconcentration: Electrokinetic supercharging
  Takeshi Hirokawa, Hikaru Okamoto, Bohuslav Gas, Electrophoresis 24, 498-504 (2003)
  
• High-sensitivity capillary gel electrophoretic analysis of DNA fragments on an electrophoresis microchip using electrokintic injection with transient isotachophoretic preconcentration
  Zhongqi Xu, Takeshi Hirokawa, Tsutomu Nishine and Akihiro Arai, Journal of Chromatography A 990, 53-61 (2003)
  
• オンライン前濃縮によるキャピラリー電気泳動法およびマイクロチップ電気泳動法の高感度化
  廣川　健,岡本　光,徐　中其, 育田　夏樹, Bunseki Kagaku Bunseki Kagaku 52, 1069-1079 (2003)
  
• Electrokinetic supercharging preconcentration and microchip gel electrophoretic separation of sodium dodecyl sulfate-protein complexes
  Zhongqi Xu, Tomomi Ando, Tsutomu Nishine, Akihiro Arai and Takeshi Hirokawa, Electrophoresis 24, 3821-3827(2003)
  
• イオンクロマトグラフ分離／中性子放射化分析法と等速電気泳動分離／粒子励起Ｘ線分析法による希土類元素試料（ジジム）の分析
  竹味弘勝, 四俵北斗, 伊藤一明, 橋本義夫, 西山文隆, 廣川 健, 分析化学 51, 1063-1068 (2002)
  
• Development of a Wavelength Dispersive X-Ray Fluorescence Spectrometer Using an X-Ray CCD
  Yasushi Sato, Shinjiro Hayakawa, Yasuharu Nishida, Akinori Hamamoto, Motohiro Suzuki and Takeshi Hirokawa, Anal. Sci. 17s, i1201-1203 (2001)
  
• Development of Capillary electrophoresis ｨC Electron Ionization ｨCMass Spectrometer (CE-EI-MS)
  Natsuki Ikuta, Yojiro Hotta, Fumitaka Nishiyama, Takeshi Hirokawa, Anal. Sci. 17s, i933-935 (2001)
  
• Analysis of Rare-Earth Ions by Transient Isotachophorwtic Preconcentration-CZE
  Hikaru Okamoto, Natsuki Ikuta and Takeshi Hirokawa, Anal. Sci. 17s, i925-927 (2001)
  
• Optimization of operational modes for transient isotachophoresis preconcentration-CZE
  Takeshi Hirokawa, Hikaru Okamoto, Natsuki Ikuta and Bohuslav Gas, Anal. Sci. 17s, i185-188 (2001)
  
• Ultra Trace Characterization Using An X-Ray Microprobe at SPring-8 BL39XU
  Shinjiro Hayakawa, Susumu Tohno, Kiyoshi Takagawa, Akinori Hamamoto, Yasuharu Nishida, Motohiro Suzuki, Yasushi Sato and Takeshi Hirokawa, Anal. Sci. 17s, i115-117(2001)
  
• Single particle analysis of fixed fog droplets using SR x-ray microprobe system
  S. Tohno, S. Hayakawa, A. Nakamura, A. Hamamoto, M. Suzuki, T. Hirokawa, Y. Satoh, Y. Nishida and M. Kasahara, J. Aerosol Sci. 32s, S873-874 (2001)
  
• Enhanced Detection of Iodide in Seawater by Ion Chromatography using an ODS Column Coated with Cetyltrimethylammonium
  Kazuaki Ito, Takeshi Hirokawa, Anal. Sci. 17, 579-581(2001)
  
• CZEエレクトロフェログラムの標準化
  廣川健, 育田夏樹, 吉山竜也, 岡本光, 芝山貴幸, 真鍋雄生, Jpn J.Electroph. 45,103-109 (2001)
  
• Change of Migration Time and Separation Window accompanied by Field Enhanced Sample
  Takeshi Hirokawa, Natsuki Ikuta, Tatsuya Yoshiyama and Hikaru Okamoto, Electrophoresis 22, 3444-3448 (2001)
  
• Operational Modes for Transient Isotachophoretic Preconcentration-CZE and Detectable Concentration of Rare Earth Ions
  Takeshi Hirokawa, Hikaru Okamoto, Natsuki Ikuta and Bohuslav Gas, Electrophoresis 22, 3483-3489 (2001)
  
• High Resolution X-ray Fluorescence Measurements using a Flat Analyzer Crystal and an X-ray CCD
  Shinjiro Hayakawa, Yasushi Kagoshima, Yoshiyuki Tsusaka, Junji Matsui, and Takeshi Hirokawa, J. Trace Microprobe Tech. 19, 615-621 (2001)
  
• Isotachophoretic Separation Behavior of Rare-earth EDTA Chelates and Analysis of Minor Rare-earth Elements in an Iron Ore by Bidirectional ITP-PIXE
  Takeshi Hirokawa, Kazuhiro Nishimoto, Yang Jie, Kazuaki Ito, Fumitaka Nishiyama, Natsuki Ikuta and Shinjiro Hayakawa, J. Chromatogr. A, 919, 417-426 (2001)
  
• Development of a compact beam intensity monitor for micro x-ray absorption fine structure measurements
  Shinjiro Hayakawa, Motohiro Suzuki, Masaharu Oshima and Takeshi Hirokawa, Nucl. Instrum. Meth. A A 467-468, 901-904 (2001)
  
• Generation of an x-ray microbeam for spectromicroscopy at SPring-8 BL39XU
  Shinjiro Hayakawa, Natsuki Ikuta, Motohiro Suzuki, Masao Wakatsuki and Takeshi Hirokawa, J. Synchrotron Rad. 8, 328-330 (2001)