Home>ASTM Standards>ASTM D4905-99(R2020) pdf free download

ASTM D4905-99(R2020) pdf free download

ASTM D4905-99(R2020) pdf free download.Standard Practice for Preparation of Solution of Solid, Pasty and Powdered Vegetable Tannin Extracts
1. Scope
1.1 This practice covers a standard procedure for use in preparing the analytical solution required for the analysis of solid, pasty, or powdered vegetable tannin extracts. 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Significance and Use
4.1 The concentration of tannins in solid, pasty, and pow- dered extracts needs to be reduced to analytical strength for tannin analyses. 4.2 Vegetable tannin extracts are heterogeneous mixtures of components with varying solubility. 4.3 The solubility of such extracts is influenced by tempera- ture and concentration, which affect the degree of dispersion and size of the component particles. 4.4 Since extracts have greater solubility in hot water than cold, it is desirable to dissolve and disperse an extract in hot water and then let the solution cool slowly to standard room temperature. 4.5 It is often difficult to reduce samples of solid and particularly pasty extracts to specimen size and at the same time ensure representative sampling. Therefore, caution is advised in drawing conclusions on the precision and bias ofthe results obtained on such extracts; where difficulties in sample preparation are experienced, little confidence can be placed in the results.
5. Specimen
5.1 The specimen shall consist of a portion of the extract sample, prepared as described in Practice D6404, sufficient to give a solution containing as nearly as possible 4 g of tannin per L (not less than 3.75 g, nor more than 4.25 g, per L).
7. Procedure
7.1 Empty the sample onto a sheet ofclean, glazed paper (or suitable clean, smooth foil material), roughly crush any large lumps, and quickly mix and quarter the whole. From each quarter, take a small representative portion, quickly crush, transfer to a small, glass stoppered weighing bottle, and take to the balance. Without delay, transfer the analytical specimen to a tared container of suitable size and weigh to the nearest 0.1 mg. Each sample shall be handled individually, and all opera- tions carried out as quickly as possible up to this point, and all other precautions taken to minimize changes in moisture content. 7.2 Pasty Extracts—Where the extract has a moisture con- tent such that it cannot be ground, weigh the sample, broken or cut, into small pieces (W 1 ) and bring to approximate equilib- rium with the laboratory atmosphere by drying for several hours at a temperature not exceeding 60°C. Allow the sample to remain exposed to the air in the laboratory until the approximate equilibrium has been attained. Weigh the partially dried sample again (W 2 ). Calculate the original moisture content of the extract as in Test Method D6403, paragraph 9.3.3, except that the residual moisture in the air-dried material (B) shall be determined as in the Procedure section of Test Method D4903 instead of as in Test Method D6403, paragraph Treat the air-dried sample, prepared as above, as in paragraph 7.1, above. In such cases, calculate the results of the analysis to the basis of the original moisture before drying. 7.3 Pour approximately 200 mL of distilled water, at 95°C, into a 1-L volumetric flask and place the container with the specimen in a funnel resting in the neck of the flask. Add distilled water, at 95°C, to the extract, filling the container. Stir the contents of the container well and allow to stand for a few moments, so that any undissolved particles may settle to the bottom of the container. Decant the supernatant liquid into the flask, add more of the hot, distilled water to the contents of the container, stirred and decanted, and repeat the process until the soluble portion of the specimen has been completely dissolved and the whole of it washed into the flask. Mix the contents of the flask by swirling. Add sufficient distilled water, at 96°C, to bring the volume to approximately 900 mL and again mix the solution by swirling. The full operation of dissolving and decanting, etc., shall be carried out as quickly as possible, and at no time during the operation shall the temperature of the solution fall below 80°C. If necessary, apply heat to keep the solution above 80°C.

Maybe you like

Standards Tags