pH measurement problems affecting assay of carcinoembryonic antigen

J. H. Ladenson, C. E. Bell

Research output: Contribution to journalArticle

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Measurement with combination pH electrodes of the pH of the dilute buffers used in a commercial kit (CEA Roche) for assay of carcinoembryonic antigen resulted in pH values 0.1 to 0.3 unit lower than pH values measured on an electrode system with a capillary junction. If the pH values of these buffers were adjusted, based on such measurements, an error in the assay of 0.2 to 0.6 ng/ml in the 1.5-3.0 ng/ml range would result. The authors recommend that the pH of dialyzed samples and of the working ethylenediaminetetraacetate and ammonium acetate acetic acid buffers be monitored with pH electrodes that have a capillary junction between sample and saturated KCl, as is true of most blood pH instruments. Recommended is the use of a 1 mol/liter rather than 2.5 mol/liter stock ammonium acetate acetic acid buffer, because of the close similarity of the pH of buffers at this molarity to those at 0.01 mol/liter. (Journal received: 13 July 1976)

Original languageEnglish
Pages (from-to)255-257
Number of pages3
JournalClinical chemistry
Issue number2
StatePublished - Dec 1 1975

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