Koichi Chiba

Major research fields

KoichiChibaAnalytical chemistry, Environmental chemistry, Chemical Metrology

The plasma atomic spectrometry is one of the most sensitive elemental analysis methods. Especially, the inductively coupled plasma mass spectrometry (ICP-MS) allows us to determine almost all the elements in the periodic table at the concentration range of sub-ppt (pg/g = 10-12 g/g) and give us the isotopic information. In our laboratory, we are trying to determine elements as many as possible in environmental and food samples such as river water, sea water, soils, sediment, particles, leaves, tissues and biological cells, and analyze the multi-elemental correlation among them for understanding the fate of elements in the environment, the total balance of elements in the environments, the integrated effects of elements on the life and so on. We call the above study “All element chemistry”. We want to understand the essentiality of the element as well as the toxicity through the all elements chemistry.

Even the ICP-MS does not have enough detection power to determine all elements in a sample. For example, it is still very difficult to determine an element at very low concentration level in a small sample such as a single cell or air-borne particles. We are developing new analytical methods, new determination techniques, and new detection systems.

The chemical speciation of an element in the environment is another most important issue in the environmental chemistry. The toxicity of element sometimes depends on its chemical form. For example, the toxicity of As is quite different among As(III), As(V) and organo-arsenic, organo-mercury is much more toxic than inorganic mercury, and Cr(VI) is very toxic although Cr(III) is safe. We are developing the chemical speciation analysis to clarify the chemical form of the elements in environment.

We are improving the understandings about the relationship between human and environment through the all element chemistry.

Major relevant publications

  1. Chiba, K., Narukawa, T., The Effect of Plasma Reaction on Arsenic Measurement by ICP spectrometry, Anal. Sci., 30, 175-181, (2014)
  2. Narukawa, T., Chiba, K., Oxygenation Mechanism of Ions in Dynamic Reaction Cell ICP-MS, Anal. Sci., 29, 747-752, (2013)
  3. Zhu, Y., Chiba, K., Internal-Standard-Method Coupled with Standard-Addition-Method for Measurement of the Elements by ICP-MS, JAAS, 27, 1000-1006, (2012)
  4. N. Nonose, A. Hioki, K. Chiba, Effect of the Detector Dead-time Uncertainty on the Analytical Result on Minor elements in Lo-alloy Steel by Isotope Dilution/ICP Sector field Mass Spectrometry Anal. Sci., 30, 871-883, (2014)
  5. K. Inagaki, S. Fuji., A. Takatsu, K. Chiba, High Performance Concentric Nebulizer for Low-Flow Rate Liquid Sample Introduction to ICP-MS JAAS 26, 623-630, (2011)