An reaction vessel utilizes a sample carrier composed of a magnetic core and a surface coating effective to support sample of protein or peptide. The sample carrier is floated magnetically and positioned within a reaction chamber. Edman reagent is applied to the sample to effect amino acid sequence analysis of protein or peptide from amino-terminal. By such construction, reaction efficiency is increased to produce sequentially thiazolinon amino-acid derivatives to thereby increase number of identified remaining amino acids, thereby enabling microanalysis of sample.