15 Chromogen/Metal Indicator



Metal Indicator

  • Product code
    N031  Nitro-PAPS
  • CAS No.
  • Chemical name
    2-(5-Nitro-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol, disodium salt, dihydrate
  • MW
Unit size Price Item Code
100 mg N031-10

Product Description

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.

Chemical Structure

Technical info


Open References

1) T. Makino, M. Kiyonaga and K. Kina, "A Sensitive, Direct Colorimetric Assay of Serum Iron Using the Chromogen, Nitro-PAPS", Clin. Chim. Acta, 1988, 171, 19.
2) T. Makino, "A Sensitive, Direct Colorimetric Assay of Serum Zinc Using Nitro-PAPS and Microwell Plates", Clin. Chim. Acta, 1991, 197, 209.
3) S. Yamashita, A. Abe and A. Noma, "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.
4) T. Yamane and H. Yamada, "Flow-injection Spectrophotometric Determination of Trace Iron in Various Salts. Elimination of Blank Peak Effect and Use of 2-(5-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol as Chromogenic Agent.", Anal. Chim. Acta, 1995, 308(1-3), 433.
5) T. Yamane and Y. Yamaguchi, "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(1-3), 139.
6) T. Yamane and Y. Yamaguchi, "2-(5-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol as a New Analytical Reagent for Flow-injection Spectrophotometric Determination of Trace Vanadium(V)", Mikrochim. Acta, 1998, 130(1), 111.

Handling and storage condition

Appearance: Dark green to dark greenish brown powder
Purity (Absorbance): ≧ 90.0 % (anhydrous)
Solubility in water: To pass test (clear, dark red)
Water content: ≦ 10.0 %
Absorbance(blank): ≦ 0.060 (566 nm)
IR spectrum: Authentic
Handling and storage condition
Ambient temperature

Product Classification

Product Classification

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