Spectrophotometric Micromethod for Protein Determination with Tetrachloro Tetraiodo Fluorescein

Abstract

Reaction of tetrachloro tetraiodo fluorescein (Na₂TCTIF) with protein results in an increase in its absorption at 568nm. This assay gives a linear response to BSA at 0.68–34.0 μg /ml, and is almost as sensitive as the Bradford method¹. The reaction is completed in approximately 2 min and has good color stability for at least 1 h. Addition of triton X-100 increases the sensitivity and stability of Na₂TCTIF binary system and the reason was studied. The binary and ternary assays were compared in protein-to-protein variability, interferences and the type of binding effort. In detection of human serum albumin, these two ways give results with good reproducibility and are comparable with the bromocresol green (BCG) method.

Key Words:

• Spectrophotometry
• Proteins
• Tetrachloro tetraiodo fluorescein disodium
• Triton X-100