Determination of trace amounts of sulfide by HPLC with fluorescence detection

A method for the determination of sulfide was developed based on HPLC with fluorescence detection. The sulfide had been converted into a fluorescent derivative with 2-amino-5-N, N-diethylaminotoluene and Fe(III) under an acidic condition. The product formed was extracted into 2-octanol as an ion-pair with sodium 1-octanesulfonate. The extract was separated by a reversed phase method (column, Inertsil ODS-2, 250 mm × 4.6 mm i.d.; mobile phase, 90% (v/v) acetonitrile aqueous solution containing sodium 1-octanesulfonate as an ion-pair reagent; flow rate, 0.5 cm3 min-1) and detected fluorometrically (excitation, 640 nm; emission, 675 nm). The sulfide could be determined over the range from 4 × 10-10 M to 4 × 10-7 M. The relative standard deviation at 4 × 10-9 M of sulfide was 3.5% (n = 7).