Colorant for fluorescent labeling and fluorescent labeling agent

Abstract

A colorant for fluorescent labeling which has an absorbance retention calculated with equation (I) of 0.5 or greater. When the colorant for fluorescent labeling is dissolved in an organic solvent and the resultant colorant solution is added to phosphate-buffered saline (PBS), then the resultant colorant dispersion (colorant dispersion I) contains dispersed colorant droplets formed therein which have an average droplet diameter of 500 nm or less. Equation (I): Absorbance retention=A1/A0 [In equation (I), A0 indicates the absorbance, at a maximum-absorption wavelength, of the colorant solution (colorant solution I) obtained by dissolving the colorant for fluorescent labeling in the organic solvent and A1 indicates the absorbance, at a maximum-absorption wavelength, of the colorant dispersion (colorant dispersion II) obtained by adding the solution of the colorant for fluorescent labeling to PBS, the colorant solution I and the colorant dispersion II being equal in colorant concentration.]

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