A new chromogenic reagent, 1-(5-nitro-3-benzopsendothiazde)-3-(4-phenylazophenyl) -triazene (NBPTPAPT) has been synthesized and used as a sensitive reagent for the spectrophotometric determination of cobalt. In the presence of Tween-80,the reagent with Co (Ⅱ) forms a yellow complex (1∶2) in the buffer solution of Na2B4O7-NaOH at pH10.54. The apparent molar absorptivity is 1.22×105L·mol-1·cm-1 with the linear range of 0-240μg/ L for Co (Ⅱ) by dual-wavelength spectrophotometry. Trace cobalt in vitamin B12 and tea samples has been determined with satisfactory results.
Constant-energy synchronous fluorimetry was used for the identification of benzo[a]pyrene in mixtures with a detection limit of 1.34 nmol/L. The recovery experiments in cigarette smoke samples have also obtained satisfactory results of 99.1-103.5% for benzo[a]pyrene.
