Impedimetric detection of galactose based on a galactose-binding lectin, Ricinus communis agglutinin I (RCA120)

•An impedimetric detection method of galactose was developed.•Galactose-binding lectin, RCA120 was used as a recognition element.•β-galactose derivative SAMs on a gold electrode was used as a glycosensor.•Quantitative detection of galactose was based on the competition reaction.•The present method can be applied to the diagnosis of galactosemia.