title: Spectrophotometric investigation of sensitive complexing agents for the determination of zinc in serum.
abstract: Of two sensitive complexometric reagents for the colorimetry of serum zinc that we investigated, one, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP), was found to be a potentially useful compound for trace-metal determinations. It has a high molar absorptivity (120 000 L mol-1 cm-1) but is not convenient to use because it is not very soluble in water. The other reagent, a related pyridylazo compound, is 2-(5-bromo-2-pyridylazo)-5-(N-n-propyl-N-3-sulfopropylamino)phenol (5-BR-PAPS). It seems better suited for use in routine zinc determinations because, besides being water soluble, it has a higher molar absorptivity, 130 000 L mol-1 cm-1. Results by the proposed method developed with 5-Br-PAPS correlated well with those by atomic absorption spectrophotometry. The between-run CV for control sera was less than 5%; the within-run CV (same controls) was less than 4%.
mesh_terms: D001391:Azo Compounds; D006801:Humans; D013053:Spectrophotometry / Q000379:methods; D015032:Zinc / Q000097:blood*
chemical_list: D001391:Azo Compounds; C037882:2-(5-bromo-2-pyridylazo)-5-diethylaminophenol; C034322:2-(5-bromo-2-pyridylazo)-5-(N-n-propyl-N-3-sulfopropylamino)phenol; D015032:Zinc