FORMER MEMBER

Shin-Ichi Ohira

Research Associate

Ph. D (Science)

sinichi.ohira@uta.edu


Research Profile

     I have studied the development of atmospheric gas determination systems by flow analysis. The target gases are collected into collection/reaction solutions then determined via conductivity, fluorometry, or spectrophotometry. Some gases are determined during the actual gas collection. Miniaturization of lab on chip gas collection effected not only small reagent consumption but also high collection/concentration efficiency. The systems I have developed have been applied to field gas measurements at volcanic craters, septic tanks and tidal flats.

     Recently, I have studied breath gas analysis, fiber optic sensor for atmospheric gases, urine analysis and capillary scale detection techniques.  The details are following.


Research Topics
(Click each topic for jump)

Breath gas analysis            Atmospheric gas analysis 

Urine analysis           Capillary scale fluorescence detector

 

Breath gas analysis

     Breath gas contains as many as ~3000 compounds.  There is equilibrium between breath gas and blood within the small capillaries in the lungs.  A clinical diagnosis can be made based on the concentrations of some of the gases measured in a breath sample, similar to the way in which blood alcohol measurements are taken.  Breath gas contains water vapor (saturated at 37 °C), several % of CO2 and many other components that cause difficulties in breath gas analysis.  We have developed specific sensors for the determination of ammonia, acetone, and isoprene. 

Breath Isoprene Analysis

     We measure isoprene with an ozone-induced chemiluminescence (CL) method.  Breath samples are collected into a sample balloon and loaded onto a column which selectively retains any isoprene in the sample.  By doing this there was not only a greatly increased sensitivity but many of the interferences listed before can be avoided.  Breath samples from various people at various times of the day were collected and analyzed for their isoprene concentration.  The comparison of the results from a gas chromatography (GC – FID/MS) method shows that our CL method has reasonable agreement for the volunteers. (Analytical Chemistry, 2007.)

                        Click figure for high-resolution pdf file.


 Atmospheric Gas Analysis

     The gases, which are invisible, are coming without recognize. Most of them are hazard for our health. In the history, we had the terrible air pollution problem (i.e. London smog (1952)).  Atmospheric gas analyses are interested not only for environmental pollution monitoring but also for environmental science. Because atmospheric gases play important roles in the natural elements cycles and so on. Many kinds of trace gas analyzer (i.e. HCHO, NH3, SO2, H2O2) were developed in our group. These are ultra high sensitive (pert per billion (ppb) or pert per trillion (ppt) levels gases can be detected.), portable, selective.

Fiber Optic Gas Sensor for Simultaneous NO2, O3 and Relative Humidity Analysis

          Fiber optic gas sensor was proposed for gas analysis.  The surface of thin layer chromatography (TLC) plate was used for gas collection and reaction.  The chemical, 8 – amino – 1 – naphthol – 5 – sulfonic acid (ANS) was impregnated to TLC plate.  This chemical responded to NO2 and O3 with brown and pink color generation, respectively.  These color development was monitored with 442 and 525 nm light emitted diodes (LEDs).  Light transmittance of TLC plate was changed by relative humidity, also.  This was monitored with infla-red LED (IR-LED).  Herein, fiber optic sensor for NO2, O3 and relative humidity was developed and applied to real atmospheric determination.  The sensor can analyze part per billion levels of NO2 and O3 gas with 5 min gas collection.  (Analytical Chemistry, submitted.)

Click figure for high-resolution pdf file


Sensing Parts per Million Levels of Gaseous NO2 by a Optical Fiber Transducer Based on Calix[4]arenes

     Alkylated calixarenes has been demonstrated as novel NO2 gas sensor.  Upon reacting with gaseous NO2, alkylated calixarenes form stable calixarene-NO+ (nitrosonium) complexes that have a deep purple color.  This specific and selective formation of the colored complex was used to develop a fiber optic based colorimetric NO2 sensor.  For a 5 min sample, the limit of detection was 0.54 ppmv with 1,3-alternate O-hexyl calix[4]arene.  With calixarenes however, such a reaction is potentially reversible - color formed upon reaction with NO2 can be reversed by flushing the sensing plate by purified air. While we found that the removal of the developed color can be accelerated by simultaneous heating and suction, permitting the reuse of the same sensing area multiple times, we also observed that the sensitivity gradually decreased. The nitrosonium calixarene derivative tends to transform to the nitrated form; this process is catalyzed by light. Several methylated calixarenes were synthesized and tested but a fully satisfactory solution has proven elusive.  (Talanta, in print.)

Click figure for high-resolution pdf file

Urine Analysis

     Urine is also strongly related with the condition of our body. Urine, which is easily collected, has been analyzed for clinical diagnosis, drug test and chemical exposure assessment for several decades. However, urine concentrations are highly variable through time. These are caused the amount of water intake, sweat and the properties of the foods eaten. The effect of the concentration variation should be corrected for urine analysis.  There is the golden standard method to solve the variation problems. It is called “Creatinine adjustment”. Creatinine is a metabolic byproduct created from creatine, which is related with the energy storage cycle of the muscles in our body. Urinary creatinine has specific property as standard like enough amount (~1.5 g/L), not interfered from biological factor and small variation.


Automated Measurement of Urinary Creatinine

     Rapid, low cost and accurate creatinine analysis system is proposed for chemical assessment.  Creatinine and alkaline picric acid develop red-yellow dye (Jaffé reaction).  Zone-fluidic analysis (ZF) was combined with kinetic spectrophotometry to avoid urine color interference.  The system can analyze 72 times in one hour.  And obtained results are well matched with LC- UV / MS methods.  (Analytical Biochemistry, 2008.)


Click figure for high-resolution pdf file


Evaluation of Creatinine Adjustment for Urinary Excretion in Lactating Mothers

       Creatinine adjustment is widely used for the estimation of 24 hr urinary excretion from spot urine samples.  We have compared creatinine adjustment values and real 24 hr values.  Creatinine adjustment was applied to perchlorate, iodine, selenium, and thiocyanate collected from lactating mothers.  Creatinine has been analyzed with automated analyzer, which is described on above.  Iodine and selenium was analyzed with ICP –MS.  Perchlorate and thiocyanate was analyzed with IC – MS/MS.  There were poor relationships between estimates and actual measured.  Also, I have collected all spot samples for 5 days in series.  Creatinine excretion and iodine excretion was not stable because these were affected by the meal taken.  (Environmental Science and Technology, 2008.)



Click figure for high-resolution pdf file


Capillary Scale Fluorescence Detector

     There has been a significant interest in capillary scale separation and detection techniques during present decade.  The capillary scale analysis gave  high and rapid separation efficiency with low reagent and sample consumption.  However, the detection techniques in this scale have the difficulties because of low amount of analyte.  We have tried highly sensitive fluorescence detection with capillary format.

Capillary Scale Liquid Core Waveguide Based Fluorescence Detector for Liquid Chromatography and Flow Analysis

     Fluorescence detection technique is highly sensitive method for chemical analysis.  We have developed liquid core waveguide (LCW) based capillary scale fluorescence detector.  The fluorescence was excited in Teflon AF coated capillary by high power UV-LED or “Blu-ray” laser diode.  Emitted light was transferred in the capillary to the photo detector, like photodiode, miniature photo multiplier tube (m-PMT).  With “Blu-ray” laser diode (405 nm), the Coumarin-30 dye was detected with 3 fmol of limit of detection (LOD).  (Talanta, 2008.)



Click figure for high-resolution pdf file

Education

·         Kumamoto University, Japan, Ph. D (Science), 2005.

·         Kumamoto University, Japan, M. D. (Science), 2002.

·         Kumamoto University, Japan, B. D., 2000.
 

Fellowships and Funding

·         2006 – 2008       JSPS Post Doctoral Research Fellow for research abroad

                                     2006              Texas Tech University

                                     2007 – 2008 University of Texas at Arlington

·         2004 – 2006       JSPS Post Doctoral Research Fellow
 

Publications

1.      Shin-Ichi Ohira, Eranda Wanigasekara, Dmitry M. Rudkevich, Purnendu K. Dasgupta, “Sensing Parts per Million Levels of Gaseous NO2 by a Optical Fiber Transducer Based on Calix[4]arenes”, Talanta, in print DOI:10.1016/j.talanta.2008.10.024

2.      Shin-Ichi Ohira, Andrea B. Kirk, Purnendu K. Dasgupta, “Automated Measurement of Urinary Creatinine by Multichannel Kinetic Spectrophotometry”, Analytical Biochemistry, 384 (2), pp.238 244 (2009).  DOI:10.1016/j.ab.2008.10.015

 

3.      Shin-Ichi Ohira, Andrea B. Kirk, Jason V. Dyke, Purnendu K. Dasgupta, “Creatinine Adjustment of Spot Urine Samples and 24 h Excretion of Iodine, Selenium, Perchlorate, and Thiocyanate”, Environmental Science and Technology, 42 (24), pp.9419 9423 (2008) DOI: 10.1021/es8020952

4.      Purnendu K. Dasgupta, Andrea B. Kirk, Jason V. Dyke, Shin-Ichi Ohira, “Intake of Iodine and Perchlorate and Excretion in Human Milk”, Environmental Science and Technology, 42 (21), pp.8115 8121 (2008).  DOI:10.1021/es801549w

5.      Masanobu Mori, Tomotaka Iwata, Tatsuya Satori, Shin-Ichi Ohira, Hideyuki Itabashi, Kazuhiko Tanaka, “Ion-Exclusion/Cation-Exchange Chromatographic Determination of Common Inorganic Ions in Human Saliva by Using an Eluent Containing Zwitterionic Surfactant”, Journal of Chromatography A, 1213, pp.125 129 (2008).  http://www.sciencedirect.com/scidirimg/clear.gifDOI:10.1016/j.chroma.2008.08.001

6.      Guanqun Song, Villanueva-Fierro Ignacio, Shin-Ichi Ohira, Purnendu K. Dasgupta, “Capillary Scale Liquid Core Waveguide Based Fluorescence Detector for Liquid Chromatography and Flow Analysis”, Talanta, 77 (2), pp.901 908 (2008).  DOI:10.1016/j.talanta.2008.07.047

7.      Maather F. Sawalha, Mrinal K. Sengupta, Shin-Ichi Ohira, Ademola D. Idowu, Thomas E. Gill, Lila Rojo, Melanie Barnes, Purnendu K. Dasgupta, Measurement of Soil/Dust Arsenic by Gas-Phase Chemiluminescence”, Talanta, 77 (1), pp.372 – 379 (2008).  DOI:10.1016/j.talanta.2008.06.037

8.      Shin-Ichi Ohira, Kei Toda, “Micro Gas Analyzers for Environmental and Medical Applications”, Analytica Chimica Acta, 619 (2), pp.143 – 156 (2008).  DOI:10.1016/j.aca.2008.05.010

 

9.      Kei Toda, Yuki Hato, Shin-Ichi Ohira, Takao Namihira, “Micro Gas Analysis System for Measurement of Nitric Oxide and Nitrogen Dioxide: Respiratory Treatment and Environmental Mobile Monitoring”, Analytica Chimica Acta, 603(1), pp. 60 – 66 (2007).  DOI:10.1016/j.aca.2007.09.052  

10.  Shin-Ichi Ohira, Jianzhong Li, William A. Lonneman, Purnendu K. Dasgupta, Kei Toda, “Can Breath Isoprene be Measured by Ozone Chemiluminescence?”, Analytical Chemistry, 79(7), pp. 2641 – 2649 (2007).  (Accelerated articles)  DOI: 10.1021/ac062334y

11.  Shin-Ichi Ohira, Kiyoshi Someya, Kei Toda, “In situ Gas Generation for Micro Gas Analysis System”, Analytica Chimica Acta, 588(1), pp. 147 – 152 (2007).  DOI:10.1016/j.aca.2007.01.069

12.  Kei Toda, Shin-Ichi Ohira, Yu-ki Hato, Takao Namihira, “Sequential Multiple Analyses of Atmospheric Nitrous Acid and Nitrogen Oxides”, Talanta, 71(4), pp. 1652 – 1660 (2007).DOI:10.1016/j.talanta.2006.07.054

 

13.  Md. Abul Kalam Azad, Shin-Ichi Ohira, Kei Toda, “Single Column Trapping/Separation and Chemiluminescence Detection for On-Site Measurement of Methyl Mercaptan and Dimethyl Sulfide”, Analytical Chemistry, 78 (17), pp. 6252 – 6259 (2006).  DOI :10.1021/ac060928v

14.  Shin-Ichi Ohira, Kei Toda, “Ion Chromatographic Measurement of Sulfide, Methanethiplate, Sulfite and Sulfate in Aqueous and Air Samples”, Journal of Chromatography A, 1121 (2), pp. 280 – 284 (2006).  DOI :10.1016/j.chroma.2006.05.074

15.  Shin-Ichi Ohira, Md. Abul Kalam Azad, Rika Kuraoka, Takayoshi Tanaka, Kotaro Mori, Kei Toda, “Long-term and Mobilic Monitoring of Atmospheric Sulfur Dioxide and Hydrogen Sulfide at Mt. Aso and Kumamoto City”, Bunseki Kagaku, 55 (2), pp. 109 – 116 (2006). (Written in Japanese)  DOI :10.2116/bunsekikagaku.55.109

16.  Shin-Ichi Ohira, “Study on the Measurement of Atmospheric Gaseous Sulfur Compounds by means of Miniature Diffusion Scrubbers”, Bunseki Kadgaku, 55 (1), pp. 61 – 62 (2006). (Written in Japanese) LINK

17.  Shin-Ichi Ohira, Kei Toda, “Miniature Liquid Flow Sensor and Feedback Control of Electroosmotic and Peumatic Flows for a Micro Gas Analysis System”, Analytical Sciences, 22 (1), pp. 61 – 65 (2006).  DOI :10.2116/analsci.22.61

18.  Kei Toda, Shin-Ichi Ohira, Md Abul Kalam Azad, “Portable Instrument for On-site Measurement of Odorous Sulfur Gases”, Proceeding of 2nd International Conference on Environmental Science and Technology, 2006(1), pp. 485 – 489 (2006).  LINK

19.  Takao Namihira, Shunsuke Sakai, Koji Matsunaga, Douyan Wang, Tsuyoshi Kiyan, Hidenori Akiyama, Kazuhumi Okamoto, Shin-Ichi Ohira, Kei Toda, “Temperature Measurement of Pulsed Arc Discharge”, Proceedings of 16th International Conference on Gas Discharges and their Applications, Xi'an, China, 2, pp. 657 – 660 (2006).

 

20.  Shin-Ichi Ohira, Kei Toda, “Micro Gas Analysis System for Measurement of Atmospheric Hydrogen Sulfide and Sulfur Dioxide”, Lab on a Chip, 5 (12), pp. 1375 – 1379 (2005).  DOI :10.1039/b511281h

21.  Md. Abul Kalam Azad, Shin-Ichi Ohira, Mitsutomo Oda, Kei Toda, “On-site Measurements of Hydrogen Sulfide and Sulfur Dioxide Emissions from Tidal Flat Sediments of Ariake Sea, Japan”, Atmospheric Environment, 39 (33), pp. 6077 – 6087 (2005).  DOI :10.1016/j.atmosenv.2005.06.042

 

22.  Kei Toda, Shin-Ichi Ohira, Misuzu Ikeda, “Micro-Gas Analysis System (µGAS) Comprising a Microchannel Scrubber and a Micro-Fluorescence Detector for Measurement of Hydrogen Sulfide”, Analytica Chimica Acta, 511(1), pp. 3 – 10 (2004).  DOI: 10.1016/j.aca.2004.01.040 

23.  Kei Toda, Shin-Ichi Ohira, Takayoshi Tanaka, Tomohiko Nishimura, Purnendu K. Dasgupta, “Field Instrument for Simultaneous Large Dynamic Range Measurement of Atmospheric Hydrogen Sulfide, Methanethiol and Sulfur Dioxide”, Environmental Science and Technology, 38 (5), pp. 1529 – 1536 (2004).  DOI: 10.1021/es034450d

 

24.  Kei Toda, Ken-Ichi Yoshioka, Shin-Ichi Ohira, Jianzhong Li, Purnendu K. Dasgupta, “Trace Gas Measurement with an Integrated Porous Tube Collector/Long-path Absorbance Detector” Analytical Chemistry, 75 (16), pp. 4050 – 4056 (2003).  DOI: 10.1021/ac0341719

 

25.  Shin-Ichi Ohira, Kei Toda, Shin-Ichiro Ikebe, Purnendu K. Dasgupta, ”Hybrid Microfabricated Device for Field Measurement of Atmospheric Sulfur Dioxide”, Analytical Chemistry, 74 (22), pp. 5890 – 5896 (2002).  DOI: 10.1021/ac025940b

 

26.  Kei Toda, Purnendu K. Dasgupta, Jianzhong Li, Gary A. Tarver, Gregory M. Zarus, Shin-ichi Ohira, “Measurement of Atmospheric Hydrogen Sulfide by Continuous Flow Fluorometry”, Analytical Sciences, 17, pp. i407 – i410 (2001).  LINK

 

27.  Kei Toda, Hiroshi Inoue, Shin-Ichi Ohira, Isao Sanemasa, “High Sensitive Micro Detector for Sulfur Dioxide”, Ryusan to Kogyo , 52 (10), pp. 129 – 134 (1999). (Written in Japanese)

  Links

Prof. Kei Toda (Kumamoto University, Japan)

The Japan Society for Analytical Chemistry

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