Dichlorofluorescein

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Description

An orange reagent used as a fluorescent indicator for the presence of oils and fats. Dichlorofluorescein (DCF) is available as a powder or a premixed solution of 0.2% in ethanol. The lipid environment can effect the fluorescence color; DCF fluoresces pink in saturated lipids and bright yellow in unsaturated lipids (Wolbers et al., 1990). Acrylics can give a positive result.

Synonyms and Related Terms

4,5-dichlorofluorescein; D&C Orange no.8 (delisted); DCF; 4,5-dichloro-3,6-fluorandiol; fluorescein chloride

Other Properties

Soluble in ethanol and dilute alkali. Slightly soluble in glycols and glycerol. Insoluble in water, dilute acids, oils, fats and waxes.

Maximum absorption wavelength=513 nm; Maximum emission wavelength= 532 nm.

The fluorescence of dichlorofluorescein changes with pH. It is colorless below pH=4.0 and green fluorescent above 5.0.

Composition C20H10Cl2O5
CAS 2320-96-9
Molecular Weight mol. wt. = 401.19

Additional Information

° R. Wolbers, N. Sterman, C. Stavroudis, "Notes for Workshop on New Methods in the Cleaning of Paintings", Getty Conservation Institute, Los Angeles, 1990.

° John M.Messinger "Ultraviolet-Fuorescence Microscopy of Paint Cross Sections" JAIC 31(3):267-74, 1992

Sources Checked for Data in Record

  • Richard C. Wolbers, Nanette T. Sterman, Chris Stavroudis, Notes for Workshop on New Methods in the Cleaning of Paintings, J.Paul Getty Trust, Los Angeles, 1990
  • The Merck Index, Susan Budavari (ed.), Merck Research Labs, Whitehouse Station, NJ, 12th Edition, 1996 Comment: entry 3051; CAS=2320-96-9
  • CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: The fluorescence of dichlorofluorescein changes with pH. It is colorless below pH=4.0 and green fluorescent above 5.0.
  • Sigma Dyes, Stains and Natural Pigments, Infrared Library, Nicolet, 1991-1995 Comment: OMNIC: formula= C20H10Cl2O5, CAS= 76-54-0