Toda Research Group|Department of Chemistry, Kumamoto University Analytical Chemistry, Atmospheric Chemistry, Environmental Chemistry

Kumamoto University

Research Interests

We are exploring analytical chemistry which makes available what are not unable so far. We investigate chemistry of atmosphere and water environment using our original devices and latest analytical instruments. Also analytical chemistry for simple medical diagnosis, from a single drop of blood and breath air, is also our interest.

Chemistry in forest atmosphere

We monitored biogenic volatile organic compounds (BVOCs) and secondary produced compounds from the BVOCs. The BVOCs contribute to enhancement of oxidants. We evaluated the effect of anthropogenic (AVOCs) and BVOCs on the incrementing oxidants and showed that BVOCs contributed this more than AVOCs, especially isoprene (C5H10) is the most important BVOCs to increase oxidant concentrations. Also BVOCs produce several compounds: e.g. 70% of formaldehyde produced in the forest were produced from isoprene in the reaction with OH radical. Devices, we developed, made enable to monitor trace volatile compounds semi-continuously.

Chemistry of atmospheric particles

Aerosols are special small particles in the atmosphere which have large specific surface area. The surface of aerosol can be an interface for absorption/desorption of volatile compounds and also can be a catalyst where several kinds of redox reactions occur. The chemistries of aerosol are not understood well, and we, chemists, have several interesting topics on cutting edges regarding the atmospheric particles including PM2.5.

Volcanic gases

Volcanic gases such as hydrogen sulfide and sulfur dioxide are one of the barometers to understand activity of volcanos. We are having long term trends and spatial variations of volcanic gases using μGAS (micro gas analysis system). Monitoring of such these gases are not only in volcano but also in Ariake Sea for estimating emission of sulfur gases from tidal flat and in pig productions for analyzing odorous reduced sulfur compounds.

Mysteries of naturally produced chemicals

Now in progress and details will be reported later.

Micro gas analysis system (μGAS)

We developed miniature gas collection devices using microchannel arranged in honeycomb pattern covered with a gas permeable hydrophobic membrane. The device made the absorbing solution layer very thin with large collection area, and this made the collection efficiency 20,000 times greater compared to the conventional impinger. So that trace level of water soluble gases can be analyzed continuously. In addition, μGAS can be operated by a small battery and mobile monitoring can be performed.
Other than the microchannel scrubber, several necessary techniques were developed for μGAS such as micro fluorescence detector, micro liquid flow sensor, micro flow control valve, micro standard gas generator.

Micro ion extractor

Device to extract analyte ions from a single drop of whole blood for instrumental analysis without centrifuging or protein removal. Analysis and diagnosis can be performed only from sampling a single drop of whole blood.