1、Designation: D 4905 99 (Reapproved 2004)Standard Practice forPreparation of Solution of Solid, Pasty and PowderedVegetable Tannin Extracts1This standard is issued under the fixed designation D 4905; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 req
3、uired for the analysis ofsolid, pasty, or powdered vegetable tannin extracts.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determ
4、ine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 4903 Test Method for Total Solids and Water in VegetableTanning Material ExtractsD 4904 Practice for Cooling of Analytical SolutionsD 6403 Test Method for Determining Moisture in Raw andSpent M
5、aterialsD 6404 Practice for Sampling of Vegetable Materials Con-taining Tannin2.2 ALCA Method:A11 Preparation of Solution of Solid, Pasty, and PowderedExtracts33. Summary of Practice3.1 This practice describes a procedure to follow in thepreparation of analytical strength solutions from samples ofso
6、lid, 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 strength fortannin analyses.4.2 Vegetable tannin extracts are heterogeneous mixtures ofcomponents with varying solubili
7、ty.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 greater solubility in hot water thancold, it is desirable to dissolve and disperse an extract in hotwater and then
8、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 representative sampling. Therefore, caution isadvised in drawing conclusions on the precision and bias of theresult
9、s 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 of the extractsample, prepared as described in Practice D 6404 , sufficient togive a solution containing as nearl
10、y as possible4goftanninper 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 Pestle.6.4 1-L Volumetric Flask, M.C.A. type, mixing bulb style.7. Procedure7.1 Empty the sample onto a sheet of clea
11、n, 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, quickly crush,transfer to a small, glass stoppered weighing bottle, and take tothe balance. Without delay, transfer th
12、e analytical specimen to1This practice is under the jurisdiction of ASTM Committee D31 on Leather andis the direct responsibility of Subcommittee D31.01 on Vegetable Leather. Thispractice has been adapted from and is a replacement for Method A11 of the OfficialMethods of the American Leather Chemist
13、s Association.Current edition approved April 1, 2004. Published May 2004. Originallyapproved in 1989. Last previous edition approved in 1999 as D 490599.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSt
14、andards volume information, refer to the standards Document Summary page onthe ASTM website.3Official Methods of the American Leather Chemists Association. Availablefrom the American Leather Chemists Association, University of Cincinnati, P.O.Box 210014, Cincinnati, OH 452210014.1Copyright ASTM Inte
15、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.a tared container of suitable size and weigh to the nearest 0.1mg. Each sample shall be handled individually, and all opera-tions carried out as quickly as possible, up to this point, and allother precauti
16、ons 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 sample, broken orcut, into small pieces (W1) and bring to approximate equilib-rium with the laboratory atmosphere by drying for severalhours at a temp
17、erature not exceeding 60C. Allow the sampleto remain exposed to the air in the laboratory until theapproximate equilibrium has been attained. Weigh the partiallydried sample again (W2). Calculate the original moisturecontent of the extract as in Test Method D 6403, paragraph9.3.3, except that the re
18、sidual moisture in the air-dried material(B) shall be determined as in the Procedure section of TestMethod D 4903 instead of as in Test Method D 6403, para-graph 9.3.1.7.2.1 Treat the air-dried sample, prepared as above, as inparagraph 7.1, above. In such cases, calculate the results of theanalysis
19、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 container with thespecimen in a funnel resting in the neck of the flask. Adddistilled water, at 95C, to the extract, filling the container. Stirthe c
20、ontents 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 supernatant liquid into theflask, add more of the hot, distilled water to the contents of thecontainer, stirred and decanted, and repeat the proces
21、s 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. Add sufficient distilled water, at 96C, tobring the volume to approximately 900 mL and again mix thesolution by swirling. The full operation of
22、 dissolving anddecanting, etc., shall be carried out as quickly as possible, andat no time during the operation shall the temperature of thesolution fall below 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 4
23、0 % formaldehyde and mix thesolution again. In any event, the addition of 3 to 4 drops oftoluene is recommended to ensure against mold growth duringthe overnight cooling.7.5 Prepare duplicate solutions, of 1 L each. It is permissibleto prepare duplicate 2-L solutions, in which case all appropriatevo
24、lumes shall be doubled.7.6 The solution shall be cooled as directed in PracticeD 4904.8. Keywords8.1 analytical solution; tannin analysis; vegetable tanninanalysisASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this s
25、tandard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be re
26、viewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of therespons
27、ible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee 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 aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 4905 99 (2004)2
