Sodium beta-naphthoquinone-4-sulfonate

Sodium beta-naphthoquinone-4-sulfonate (CAS 521-24-4), commonly abbreviated as NQS, is a water-soluble quinone reagent used in analytical and pharmaceutical chemistry.

It functions as a chromogenic derivatizing agent, reacting with primary and secondary amines to produce colored complexes measurable by spectrophotometry for various applications.

NQS is used in pharmaceutical quality control for the colorimetric determination of amino-containing active pharmaceutical ingredients, including sulfonamides and aminoglycosides.

This enables quantitative assay development without chromatographic separation. In clinical and biochemical analysis, it supports the detection and quantification of amino acids.

Biotechnology workflows use NQS as a labeling reagent for amine-functionalized compounds, supporting assay development and compound characterization at research and pilot scale.

It also appears in the development of stability-indicating methods, where its selective reactivity with amine groups helps identify degradation products in drug formulations.

Sodium beta-naphthoquinone-4-sulfonate is supplied as a solid powder, typically in high-purity grades suited for analytical and pharmaceutical research applications.

Material is generally available at reagent or research grade, with purity specifications commonly at 97% or higher. Packaging ranges from small laboratory quantities to bulk orders.