1、Designation: D4905 99 (Reapproved 2016)Standard Practice forPreparation of Solution of Solid, Pasty and PowderedVegetable Tannin Extracts1This standard is issued under the fixed designation D4905; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a standard procedure for use inpreparing the analytical solution requir
3、ed for the analysis ofsolid, pasty, or powdered vegetable tannin extracts.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its u
4、se. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D4903 Test Method for Total Solids and Water in VegetableTanning Material
5、ExtractsD4904 Practice for Cooling of Analytical SolutionsD6403 Test Method for Determining Moisture in Raw andSpent MaterialsD6404 Practice for Sampling Vegetable Materials Contain-ing Tannin2.2 ALCA Method:A11 Preparation of Solution of Solid, Pasty, and PowderedExtracts33. Summary of Practice3.1
6、This practice describes a procedure to follow in thepreparation of analytical strength solutions from samples ofsolid, pasty, and powdered vegetable tannin extracts.4. Significance and Use4.1 The concentration of tannins in solid, pasty, and pow-dered extracts needs to be reduced to analytical stren
7、gth fortannin analyses.4.2 Vegetable tannin extracts are heterogeneous mixtures ofcomponents with varying solubility.4.3 The solubility of such extracts is influenced by tempera-ture and concentration, which affect the degree of dispersionand size of the component particles.4.4 Since extracts have g
8、reater solubility in hot water thancold, it is desirable to dissolve and disperse an extract in hotwater and then let the solution cool slowly to standard roomtemperature.4.5 It is often difficult to reduce samples of solid andparticularly pasty extracts to specimen size and at the sametime ensure r
9、epresentative sampling. Therefore, caution isadvised in drawing conclusions on the precision and bias of theresults obtained on such extracts; where difficulties in samplepreparation are experienced, little confidence can be placed inthe results.5. Specimen5.1 The specimen shall consist of a portion
10、 of the extractsample, prepared as described in Practice D6404, sufficient togive a solution containing as nearly as possible 4 g of tanninper L (not less than 3.75 g, nor more than 4.25 g, per L).6. Apparatus and Reagents6.1 Formaldehyde40 % solution.6.2 TolueneAssay 99.5 %.6.3 Small Mortar and Pes
11、tle.6.4 1-L Volumetric Flask, M.C.A. type, mixing bulb style.7. Procedure7.1 Empty the sample onto a sheet of clean, glazed paper (orsuitable clean, smooth foil material), roughly crush any largelumps, and quickly mix and quarter the whole. From eachquarter, take a small representative portion, quic
12、kly crush,transfer to a small, glass stoppered weighing bottle, and take tothe balance. Without delay, transfer the analytical specimen to1This practice is under the jurisdiction ofASTM Committee D31 on Leather andis the direct responsibility of Subcommittee D31.01 on Vegetable Leather. Thispractice
13、 has been adapted from, and is a replacement for, MethodA11 of the OfficialMethods of the American Leather Chemists Association.Current edition approved Sept. 1, 2016. Published October 2016. Originallyapproved in 1989. Last previous edition approved in 2009 as D4905 99 (2009).DOI: 10.1520/D4905-99R
14、16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Official Methods of the American Leather Chemists Associa
15、tion. Availablefrom the American Leather Chemists Association, University of Cincinnati, P.O.Box 210014, Cincinnati, OH 452210014.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1a tared container of suitable size and weigh to the near
16、est 0.1mg. Each sample shall be handled individually, and all opera-tions carried out as quickly as possible up to this point, and allother precautions taken to minimize changes in moisturecontent.7.2 Pasty ExtractsWhere the extract has a moisture con-tent such that it cannot be ground, weigh the sa
17、mple, broken orcut, into small pieces (W1) and bring to approximate equilib-rium with the laboratory atmosphere by drying for severalhours at a temperature not exceeding 60C. Allow the sampleto remain exposed to the air in the laboratory until theapproximate equilibrium has been attained. Weigh the
18、partiallydried sample again (W2). Calculate the original moisturecontent of the extract as in Test Method D6403, paragraph9.3.3, except that the residual moisture in the air-dried material(B) shall be determined as in the Procedure section of TestMethod D4903 instead of as in Test Method D6403, para
19、graph9.3.1.7.2.1 Treat the air-dried sample, prepared as above, as inparagraph 7.1, above. In such cases, calculate the results of theanalysis to the basis of the original moisture before drying.7.3 Pour approximately 200 mL of distilled water, at 95C,into a 1-L volumetric flask and place the contai
20、ner with thespecimen in a funnel resting in the neck of the flask. Adddistilled water, at 95C, to the extract, filling the container. Stirthe contents of the container well and allow to stand for a fewmoments, so that any undissolved particles may settle to thebottom of the container. Decant the sup
21、ernatant liquid into theflask, add more of the hot, distilled water to the contents of thecontainer, stirred and decanted, and repeat the process until thesoluble portion of the specimen has been completely dissolvedand the whole of it washed into the flask. Mix the contents ofthe flask by swirling.
22、 Add sufficient distilled water, at 96C, tobring the volume to approximately 900 mL and again mix thesolution by swirling. The full operation of dissolving anddecanting, etc., shall be carried out as quickly as possible, andat no time during the operation shall the temperature of thesolution fall be
23、low 80C. If necessary, apply heat to keep thesolution above 80C.7.4 If the solution is likely to ferment (myrabolans ordivi-divi), add 1 mL of 40 % formaldehyde and mix thesolution again. In any event, the addition of 3 to 4 drops oftoluene is recommended to ensure against mold growth duringthe over
24、night cooling.7.5 Prepare duplicate solutions of 1 L each. It is permissibleto prepare duplicate 2-Lsolutions, in which case all appropriatevolumes shall be doubled.7.6 The solution shall be cooled as directed in PracticeD4904.8. Keywords8.1 analytical solution; tannin analysis; vegetable tanninanal
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28、mittee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddr
29、ess or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 99 (2016)2
