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Thermo Scientific™ Fluoraldehyde™ o-Phthaldialdehyde Crystals (OPA)

Measure peptides or amino acids (Ex 340nm, Em 455nm) with phthalaldehyde, a fluorescent, amine-reactive, HPLC pre- or post-column labeling reagent.

Supplier:  Thermo Scientific™ 26015

Catalog No. PI26015

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Thermo Scientific™ Pierce Fluoraldehyde (OPA) is o-phthalaldehyde, a highly sensitive fluorescent pre- or post-column derivatization reagent for peptide or amino acid detection and quantitation in HPLC.

Fluoraldehyde Crystals are a specially purified, fluorogenic-grade preparation of o-phthalaldehyde (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:

  • Can be prepared as a stable aqueous solution in borate (see instructions)

  • Alternative names: Fluoraldehyde Crystals, OPA

  • Chemical name: ortho-Phthalaldehyde

  • Reactive toward: Primary amines (–NH2)

  • Chemical formula: C8H6O2

  • CAS number: 643-79-8

  • Molecular weight: 134.12

  • Form: Pale yellow, free-flowing crystals



OPA (o-phthaldialdehyde)
5 g
Store at room temperature.


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