1、Designation: D 4901 99 (Reapproved 2004)Standard Practice forPreparation of Solution of Liquid Vegetable Tannin Extracts1This standard is issued under the fixed designation D 4901; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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 the preparation of a solution ofliquid extract that is to be used in the tannin analys
3、is of thatextract.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 determine the applica-bility of regulatory limitations prior to u
4、se.2. Referenced Documents2.1 ASTM Standards:2D 4904 Practice for Cooling of Analytical SolutionsD 6404 Practice for Sampling of Vegetable Materials Con-taining Tannin2.2 ALCA Methods:A10 Preparation of Solution of Liquid Extracts33. Summary of Practice3.1 The practice describes a technique found us
5、eful in thepreparation of analytical strength solutions from samples ofliquid vegetable tannin extracts.4. Significance and Use4.1 The concentration of tannin in extracts must be reducedto analytical strength (4 g tannin per L) for analyses.4.2 Vegetable tannin extracts are heterogeneous mixtures of
6、components 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 While the solubility is better in hot water than in coldwater, it is appropriate to dissolve and disper
7、se an extract in hotwater and then let the solution cool slowly to standard roomtemperature.5. Apparatus and Reagents5.1 Formaldehyde40 % solution.5.2 Tolueneassay $ 99.5 %.5.3 Flask, 1 L volumetric. The Class A type, with upper bulbin neck, is especially suitable for this work.6. Test Specimen6.1 T
8、he specimen shall consist of an aliquot of the sample,prepared as described in Practice D 6404, sufficient to give asolution containing as nearly as possible,4goftannin per L(not less than 3.75 g, nor more than 4.25 g, per L).7. Procedure7.1 Prepare samples of liquid extracts, as described inPractic
9、e D 6404, and allow to come to room temperature.Thoroughly mix at room temperature and transfer specimen toa tared container and stoppered to prevent loss of moisture.Return no material which has been removed from the samplefor any other purpose (for example, for determination ofspecific gravity, et
10、c.) to the sample. Care must be taken thatdried material around the neck of the stopper of the samplebottle does not contaminate the sample or specimen. Weigh thecontainer and specimen to the nearest 0.1 mg.NOTE 1Shaking by hand is rarely sufficient; mechanical shaking,especially with a clinical-typ
11、e shaker for 10 min, is preferred. In the caseof very viscous extracts, a stirrer has to be used, in which case care mustbe taken to avoid the loss of moisture.7.2 Pour approximately 200 mL of distilled water at 95Cintoa1Lvolumetric flask and immediately transfer specimens,quantitatively, into the f
12、lask with distilled water at 95C. Assoon as the specimen has been transferred, mix the contents ofthe flask by swirling. Add sufficient distilled water at 95C tobring the volume to approximately 900 mL, and mix thesolution again by swirling. The temperature of the solutionimmediately after this mixi
13、ng shall not be less than 80C. Ifnecessary, apply heat to keep the solution above 80C.7.3 If the solution is likely to ferment (myrabolans ordivi-divi), add 1 mL of 40 % formaldehyde and mix the1This practice is under the jurisdiction of ASTM Committee D31 on Leather andis the direct responsibility
14、of Subcommittee D31.01 on Vegetable Leather. Thispractice has been adapted from and is a replacement for Method A10 of the OfficialMethods of the American Leather Chemists Association.Current edition approved April 1, 2004. Published May 2004. Originallyapproved in 1989. Last previous edition approv
15、ed in 1999 as D 490199.2For 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 Leat
16、her Chemists Association. Availablefrom the American Leather Chemists Association, University of Cincinnati, P.O.Box 210014, Cincinnati, OH 452210014.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.solution again. In any event, the a
17、ddition of from 3 to 4 dropsof toluene is recommended to ensure against mold growthduring the overnight cooling.7.4 Prepare duplicate solutions, of 1 L each. It is permissibleto prepare duplicate 2 L solutions, in which case double allappropriate volumes.7.5 Cool the solution as directed in Practice
18、 D 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 standard. Users of this standard are expressly advised that determination of th
19、e 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 reviewed every five years andif not revised, either reapproved or withdrawn. You
20、r 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 theresponsible technical committee, which you may attend. If you feel that your comments
21、 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 4901 99 (2004)2
