Sørensen formol titration
The Sørensen formol titration(SFT) invented by S. P. L. Sørensen in 1907 [1][2] is a largely archaic method that was once used to determine the amino acid content of a sample. It is used in the determination of protein content in samples.[3]
In case of tyrosine, the actual results are too high due to the negative hydroxyl group (-OH), which acts as a base. This explanation is supported by the fact that phenylalanine can be accurately titrated.[2]
Method
The titration of an amino acid with potassium hydroxide in the presence of formaldehyde.[4]
In winemaking
Formol titration is used in winemaking to measure yeast assimilable nitrogen needed by wine yeast in order to complete fermentation.[5]A related analysis method is o-phthaldialdehyde/N-acetyl-L-cysteine spectrophotometric assay (NOPA).[6]
References
- ^ Sørensen Biochem Z., 7, 45, 407 1907
- ^ a b S. L. Jodidi "Abnormalities In the Formol Titration Method" Journal of American Chemical Society 1918 40 (7), 1031-1035 DOI: 10.1021/ja02240a006
- ^ Analytical Chemistry of Foods C.S. James Springer Science & Business Media, 2013
- ^ Harry Auterhoff: Lehrbuch der Pharmazeutischen Chemie, 5. Aufl., Wissenschaftliche Verlagsgesellschaft mbH Stuttgart, 1968.
- ^ B. Zoecklein, K. Fugelsang, B. Gump, F. Nury Wine Analysis and Production pgs 152–163, 340–343, 444–445, 467 Kluwer Academic Publishers, New York (1999) ISBN 0834217015
- ^ Carl E. Shively, Thomas Henick-Kling (2001). "Comparison of two procedures for assay of free amino nitrogen". American Journal of Enology and Viticulture. 52: 400-401.