Determination of free and combined plant acids

Authors

• Maija-Liisa Salo Department of Animal Husbandry, University of Helsinki
• Kaija Kotilainen Department of Animal Husbandry, University of Helsinki

DOI: https://doi.org/10.23986/afsci.71745

Abstract

A method is presented for the determination of the total amounts of plant acids and associated cations, viz. potassium, sodium, calcium and magnesium. The principle of the method is as follows: The acids and salts are extracted into water, and the cations retained by an Amberlite IR-120H+ resin using a batch technique. The acids are titrated electrometrically to pH 9.0. The cations are eluted from the resin and determined by flame photometry. As the inorganic salts present in the water extract are converted by the ion exchanger to the corresponding acids, the total acidity value is corrected for the chlorides, phosphates and nitrates present. The free and combined plant acids are calculated on the basis of the results obtained. The various stages of the analytical procedure are discussed and the results obtained in the analyses of 17 different fodders and foodstuffs are given as examples.