Nitro-PAPS is a highly sensitive colorimetric reagent for Fe(II) detection that forms a water-soluble complex at pH 3.0-8.0 (λmax=582 nm, λ=107,000). This reagent is suitable for the determination of Fe(II) in serum and can also be used to determine micromolar levels of Cu, Zn, Ni, and Co. Cu and Zn in serum are masked by a mixture of thioglycolic acid and SDS. Zn in serum can be determined by Nitro-PAPS using CN- as a masking reagent of Fe and Cu.
1. T. Makino, et al., A Sensitive, Direct Colorimetric Assay of Serum Iron Using the Chromogen, Nitro-PAPS. Clin Chim Acta. 1988;171:19-27.
2. T. Makino, A Sensitive, Direct Colorimetric Assay of Serum Zinc Using Nitro-PAPS and Microwell Plates. Clin Chim Acta. 1991;197:209-220.
3. S. Yamashita, et al., Sensitive, Direct Procedures for Simultaneous Determination of Iron and Copper in Serum, with Use of 2-(5-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol(Nitro-PAPS) as Ligand. Clin Chem. 1992;38:1373-1375.
4. T. Yamane, et al., Flow-injection Spectrophotometric Determination of Trace Iron in Various Salts. Elimination of Blank Peak Effect and Use of2-(5-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol as Chromogenic Agent. Anal Chim Acta. 1995;308:433-438.
5. T. Yamane, et al., Complex Formation of 2-(5-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol with Lead, Cadmium and Manganese for Their Sensitive Spectrophotometric Detection in Flow Injection and Ion Chromatography Systems. Anal Chim Acta. 1997;345:139-146.
Table 1 Spectral Data of Nitro-PAPS-Metal Complex