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
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.
|Molecular Weight||mol. wt. = 401.19|
° 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