2-AMINOTHIOPHENOLS AS FLUOROGENIC REAGENTS FOR AROMATIC-ALDEHYDES

Substituted 2-aminothiophenols (7 species) were evaluated for fluorescence derivatization reagents of aromatic aldehydes in spectrofluorimetry and liquid chromatography. Of the compounds, 2-amino-5-methoxythiophenol was the most favourable in practical use. The reagent reacts selectively with aromatic aldehydes in acidic media within 70 min at 50 degrees C. The fluorescent products from benzaldehyde and 4-hydroxybenzaldehyde are shown to be 2-phenyl-6-methoxybenzothiazole and 2-(4-hydroxyphenyl)-6-methoxybenzothiazole, respectively. The detection limits for aromatic aldehydes in the spectrofluorometric method were 7-80 pmol ml(-1) depending on the aldehydes. The fluorescent derivatives of aromatic aldehydes can be separated by reversed-phase chromatography and their detection limits (S/N=3) are 0.1-0.4 pmol on column.