Hisao Oka

A Nonempirical Method Using LC/MS for Determination of the Absolute Configuration of Constituent Amino Acids in a Peptide:  Combination of Marfey's Method with Mass Spectrometry and Its Practical Application

Kiyonaga Fujii, Yoshitomo Ikai, Hisao Oka et al. · Analytical Chemistry · 1997 · 468 citations

Pharmacy, Biochemistry, Analytical Chemistry +16

A Nonempirical Method Using LC/MS for Determination of the Absolute Configuration of Constituent Amino Acids in a Peptide:  Elucidation of Limitations of Marfey's Method and of Its Separation Mechanism

Kiyonaga Fujii, Yoshitomo Ikai, Tsuyoshi Mayumi et al. · Analytical Chemistry · 1997 · 343 citations

Pharmacy, Biochemistry, Chromatographic Analysis +16

Formation, characterization, and toxicity of the glutathione and cysteine conjugates of toxic heptapeptide microcystins

Fumio Kondo, Yoshitomo Ikai, Hisao Oka et al. · Chemical Research in Toxicology · 1992 · 205 citations

Pharmacy, Biochemistry, Toxicology +15

Analysis and purification of toxic peptides from cyanobacteria by reversed-phase high-performance liquid chromatography

Ken-ichi Harada, Kenji Matsuura, Makoto Suzuki et al. · Journal of Chromatography A · 1988 · 179 citations

Pharmacy, Biochemistry, Microbiology +12

Systematic search for suitable two-phase solvent systems for high-speed counter-current chromatography

Fumie Oka, Hisao Oka, Yoichiro Ito · Journal of Chromatography A · 1991 · 175 citations

Pharmacy, Chemistry, Analytical Chemistry +12