4.1 The concentration of tannin in extracts must be reduced to analytical strength (4 g tannin per L) for analysis.

4.2 Vegetable tannin extracts are heterogeneous mixtures of components with varying solubility.

4.3 The solubility of such extracts is influenced by temperature and concentration, which affect the degree of dispersion and size of the component particles.

4.4 While the solubility is better in hot water than in cold water, it is appropriate to dissolve and disperse an extract in hot water and then let the solution cool slowly to standard room temperature.

1.1 This practice covers the preparation of a solution of liquid extract that is to be used in the tannin analysis of that extract.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.