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Fluoraldehyde o-Phthaldialdehyde Crystals

Fluorescent compound for amino acid detection.

Pierce Fluoraldehyde (OPA)

Thermo Scientific Pierce Fluoraldehyde Crystals are o-phthaldialdehyde (OPA), a highly sensitive fluorescent derivatization reagent for peptide or amino acid detection and quantitation in HPLC.

Fluoraldehyde Crystals are a specially purified, fluorogenic-grade preparation of o-phthaldialdehyde (OPA). This amine-reactive compound is primarily used for high-sensitivity, fluorescent detection of primary amines, including amino acids, peptides, proteins and polyamines in pre- or post-column chromatographic effluents.


  • For pre- or post-column amino acid derivatization for fluorescent detection and quantitation
  • Reacts with all primary amine-containing analytes to yield fluorescent derivatives (ex/em = 340nm/455nm)
  • Provides an accurate measure of both composition and absolute protein-peptide content
  • Ideal for work with recombinant proteins and synthetic peptides
  • Can be used for fluorescent protein or peptide assay
  • Can be prepared as a stable aqueous solution in borate (see instructions)

Reagent Properties:

  • Alternative names: Fluoraldehyde Crystals, OPA
  • Chemical name: ortho-phthaldialdehyde
  • Reactive toward: Primary amines (–NH2)
  • Chemical formula: C8H6O2
  • CAS number: 643-79-8
  • Molecular weight: 134.12
  • Form: Pale yellow, free-flowing crystals

Product Details:

Fluoraldehyde Crystals, o-phthaldialdehyde OPA Chemical structure of ortho-phthaldialdehyde (OPA). Thermo Scientific Fluoraldehyde Crystals are high-purity crystalline OPA. For HPLC applications, OPA is usually used as reagent solution containing 2-mercaptoethanol. Consider using our ready-to-use Fluoraldehyde Reagent (Part No. 26025).

For even greater sensitivity, use a combination of OPA and Fmoc-Chloride with automated pre-column derivatization to detect both primary and secondary amines. With this application, primary amino acids are first derivatized with OPA and then remaining secondary amino acids are reacted with Fmoc-Chloride, resulting in extraordinary amino acid detection sensitivity and accuracy (see Lindroth and Mopper, 1979; Lee and Drescher, 1979).


  1. Lindroth, P. and Mopper, K. (1979). Anal. Chem. 51, 1667-1674.
  2. Lee, K.S. and Drescher, D.G. (1979). J. Biol. Chem. 254, 6248-6251.
  3. van Eijk, H.M.H., et al. (1988). Clin. Chem. 34, 2510-2513.
  4. Graser, T.A., et al. (1985). Anal. Biochem. 151, 142-152.
  5. Godel, H., et al. (1984). J. Chrom. 297, 49-61.
  6. Sista, H.S. (1986). J. Chrom. 359, 231-240.
  7. Cooper, J.D.H., et al. (1984). Anal. Biochem. 142, 98-102.
  8. Krishnamurti, C.R., et al. (1984). J. Chrom. 315, 321-331.
  9. Jones, B.N., et al. (1983). J. Chrom. 266, 471-482.
  10. Lee, H., et al. (1979). Anal. Biochem. 96, 298-307.
  11. Chen, R.F., et al. (1979). Biochem. Biophys. Acta. 576, 440-455.
  12. Jones, B.N., et al. (1981). J. Liq. Chrom. 4, 565-586.
  13. Benson, J.R. and Woo, D.J. (1984). J. Chromatogr. Sci. 22, 386-399.
  14. Krause, R.J., et al. (2002). Drug Metab. Dispos. 30, 1137.
  15. Atkinson, B.N., et al. (2001). Mol. Pharmacol. 60: 1414.

Ordering Information
Product # Description Pkg. Size Instructions MSDS CofA Price
26015 Fluoraldehyde o-Phthalaldehyde Crystals
Formulation: o-Phthalaldehyde; granular crystals
Sufficient For: Preparing 6 to 10L of typical 1X assay solution
5g Product Instructions for product #26015 Fluoraldehyde o-Phthalaldehyde Crystals MSDS for product #26015 Fluoraldehyde o-Phthalaldehyde Crystals Certificate of Analysis for product #26015 Fluoraldehyde o-Phthalaldehyde Crystals $267.00

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Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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