A Thermometric Investigation of the Reaction between Proteins and 12-Phosphotungstic Acid
Proteins in acid solution may be precipitated by the addition of a wide variety of anions including perchlorate, trifluoroacetate and tungstate(l). We have recently developed (2) a thermometric titration procedure for total serum protein based on their quantitative precipitation by 12-phosphotungstic acid (H3PW12O40). End point precision was~0 .5% when the total protein concentration was in the range of 1–10 g/l. Outside this range the precision deteriorates and the stoichiometry is not constant. At low protein concentration the reaction kinetics are too slow thereby inducing a positive error(3); while at high protein concentration the titration curve becomes quite nonlinear due to rather dramatic changes in the sample viscosity and concomitant changes in the rate of heat generation due to stirring (2).
KeywordsTitration Curve Basic Amino Acid Total Serum Protein Bovine Albumin High Protein Concentration
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- 1.R. J. Henry, Clinical Chemistry; Principles and Techniques, Harper and Row, New York, p. 163 (1964).Google Scholar