Spectrophotometric assay of phenolphthalein in biological fluids

Sarah M. Morris, D. W. Powell

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


An assay for phenolphthalein in biological fluids has been developed utilizing methods previously applied to the assay of bromosulphalein and to the deconjugation of steroidal compounds in urine. Intestinal perfusate, serum, and urine samples containing phenolphthalein are deproteinized with acidified acetone, the samples dried, and the phenolphthalein redissolved in ethanol. Color is developed with 0.5 m glycine buffer, pH 12, and the samples read at 550 nm after blanking the spectrophotometer with one of the replicates to which acidic glycine buffer is added. To measure conjugated phenolphthalein in urine, the sample is incubated overnight with β-glucuronidase/arylsulphatase prior to phenolphthalein determination as noted above. This method gives an accurate assay of phenolphthalein to 10-5 m concentrations with coefficients of variation between 2 and 8% and with no resulting interference from hemoglobin or bilirubin.

Original languageEnglish (US)
Pages (from-to)465-471
Number of pages7
JournalAnalytical Biochemistry
Issue number2
StatePublished - Jun 1979
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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