1、Designation: D 6405 99 (Reapproved 2009)Standard Practice forExtraction of Tannins from Raw and Spent Materials1This standard is issued under the fixed designation D 6405; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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 extracting the tannin from raw andspent materials. The water extract obtained by this method isu
3、sed to determine the tannin content of the original material.Analysis for total solids, soluble solids, and soluble non-tannins of the water extract from a material provides theinformation necessary to calculate the extractable tannin con-tent of that material. The types of materials typically analy
4、zedby this practice are products of plants such as woods, barks,leaves, nuts, fruits, roots, etc. and any of a wide variety ofby-products (spent materials) from industrial processes utiliz-ing plant products.1.2 The values stated in SI units are to be regarded as thestandard. The inch-pound units gi
5、ven in parentheses are forinformation only.1.3 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 regulato
6、ry limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1517 Terminology Relating to LeatherD 4903 Test Method for Total Solids and Water in VegetableTanning Material ExtractsD 4904 Practice for Cooling of Analytical SolutionsD 6401 Test Method for Determining Non-Tannins andTannin
7、in Extracts of Vegetable Tanning MaterialsD 6402 Test Method for Determining Soluble Solids andInsolubles in Extracts of Vegetable Tanning MaterialsD 6403 Test Method for Determining Moisture in Raw andSpent MaterialsD 6404 Practice for Sampling Vegetable Materials Contain-ing Tannin2.2 ALCA Methods
8、:A5 Extraction of Raw and Spent Materials33. Terminology3.1 Definitions:3.1.1 For definitions of general leather and tanning termsused in this practice refer to Terminology D 1517.3.1.2 raw materialany of the various parts of plants thatare used as a source of vegetable tannins.3.1.3 spent materialp
9、lant tissue by-products from indus-trial processes which may contain significant quantities ofvegetable tannins.3.1.4 tanninan astringent substance found in the variousparts of plants such as bark, wood, leaves, nuts, fruits, roots,etc.3.1.5 vegetable tanninsmixtures of substances (naturalproducts)
10、obtained from plant tissues by water extractionwhich have the chemical and physical properties necessary toconvert animal hides and skins into leather.4. Summary of Practice4.1 The sample of material to be analyzed for tannin contentis first brought to moisture equilibrium with the laboratoryatmosph
11、ere (that is, wet materials such as spent materials arefirst dried under ambient laboratory conditions) and thenground sufficiently to pass through a sieve. This ground sampleis then extracted with water in a steam-jacketed extractor.5. Significance and Use5.1 This practice provides a standard proce
12、dure for obtain-ing the water-soluble materials (including tannins) from anymaterial that can be prepared for and charged to the steam-jacketed extractor. The extraction solutions are then analyzedaccording to Test Methods D 4903, D 6401, and D 6402.6. Apparatus and Reagents6.1 Sieve, with circular
13、openings 1.27 cm (0.50 in.) indiameter.6.2 Sieve, with circular openings of 2 mm diameter (U.S.Std. Sieve Series No. 10).1This practice is under the jurisdiction of ASTM Committee D31 on Leather.This test method has been adapted from and is a replacement for Method A5 of theOfficial Methods of the A
14、merican Leather Chemists Association.Current edition approved April 1, 2009. Published July 2009. Originallyapproved in 1999. Last previous edition approved in 2004 as D 6405 99 (2004).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceast
15、m.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 Association. Availablefrom the American Leather Chemists Association, University of Cincinnati, P.O.Box 210014, Cincinnati, O
16、H 45221-0014.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 Glass Rods, soft glass stirring rods with rounded,fire-polished ends.6.4 Borosilicate Glass Wool, made of soft, pliable fibers.6.5 Steam-Jacketed, Borosilicate Glass Ex
17、traction Appara-tus, as described in Fig. 1. This apparatus may need to bespecial ordered and custom built by a laboratory glass-blowingmanufacturer.6.6 Tubing, flexible, chemical and heat resistant tubing ofappropriate size and length to fit onto the outlet tubes of theextractor apparatus. The tubi
18、ng from the extraction chamberoutlet must fit into the receiving flask.6.7 Clamps, Hoffman or similar type for use on the tubingextensions from the extractor outlets.6.8 Wiley Mill, or similar grinder.6.9 Balance, analytical balance which will weigh up to 100g with an accuracy of 6 0.1 mg (6 0.0001
19、g).6.10 Formaldehyde, 40 % solution.6.11 Toluene, assay $ 99.5 %6.12 Volumetric Flask, 1-L capacity for spent materials or2-L capacity for raw materials. ClassAflasks with a bulb in theneck (M.C.A. type) are especially suitable for this work.7. Preparation of Sample7.1 All of the sample, drawn as di
20、rected in Practice D 6404,shall first be ground in a rough grinder, or shredded, to pass asieve having round openings 1.27 cm (0.50 in.) in diameter.After this grinding, the sample shall be mixed and quartered, asdescribed in the Quartering Samples section of Practice D 6404until about 450 g (1 lb)
21、remains. This material shall then beground to pass a sieve having circular openings of 2 mmdiameter (U.S. Standard Sieve Series No. 10). This grindingshall be conducted in a Wiley mill or similar grinder.7.2 Where the original sample is too wet to be ground, orwhere such grinding is likely to cause
22、significant changes in themoisture content, samples of raw material shall be weighed,spread out on (canvas) trays which permit free circulation of airall around the sample, and allowed to attain approximatemoisture equilibrium with the laboratory atmosphere; thetemperature at no time should exceed 6
23、0C. Spent materialsshould be similarly treated except that temperatures up to100C may be used. The partially dried sample shall then beground as described in 7.1.7.2.1 In all cases, the loss of moisture during such dryingmust be determined and the results of the analysis calculated tothe basis of th
24、e original moisture before drying. A secondmoisture shall be run on the finely ground sample. The methodof determining these moisture values and calculating theoriginal moisture content is found in Test Method D 6403.8. Test Specimen8.1 The specimen shall consist of a quantity of the sample,prepared
25、 as described in Section 7 above, sufficient to give asclosely as possible 4 g tannin per litre of solution (not less than3.75 nor more than 4.25 g/L). In the case of materials low intannin, the specimen shall consist of the maximum quantity ofthe sample which can be extracted in the steam-jacketede
26、xtractor (see 6.3 and Fig. 1).9. Procedure9.1 Prepare duplicate extract samples. Extract raw materialsto a volume of 2 L. Extract spent materials to a volume of 1 L.9.2 Attach the extractor to a boiling-flask, which furnishessteam by the boiling of distilled water. Attach a refluxcondenser to the to
27、p of the extractor and connect to a source ofFIG. 1 Extraction ApparatusD 6405 99 (2009)2cold water. Close the outlet tube on the bottom stem of theapparatus just above the steam generating flask by attaching asection of tubing and a clamp which then can be used to helpregulate the amount of steam p
28、assing into the extractor; thismay be particularly helpful at the beginning of an extraction.Close the outlet tube of the extraction chamber by using asection of tubing (with a clamp) leading into the receivingvessel. Prepare a layer of borosilicate glass wool, 0.64 cm (0.25in.) thick, and place in
29、the bottom of the extraction chamber,over the monel disc. Transfer the specimen to a tared containerand weigh to the nearest 1 mg (0.001 g), taking everyprecaution to avoid changes in moisture content. Then wet thespecimen with a minimum of distilled water, at 95C, and stirthe mixture with a glass r
30、od to ensure complete wetting. Thentransfer the wetted specimen quantitatively, to the extractor,through a transfer funnel, using a minimum quantity of the hotdistilled water. Remove entrapped air in the charge by stirringwith a glass rod, taking care not to disturb the layer of glasswool. Open the
31、outlet tube of the extraction chamber slowlyand allow the liquid to drain into the appropriate receivingflask. At this stage, the water in the boiling-flask shall beboiling and the steam freely condensing in the jacket. As thecharge settles, rinse the stirring rod and the sides of theextractor with
32、the hot, distilled water. Return any solid materialwhich comes through with the first extract, when the outlettube is opened, to the extraction chamber. When the water hasdrained from the surface of the charge, cover the specimen witha layer of borosilicate glass wool about 0.64 cm (0.25 in.)thick,
33、and connect the condenser to the extractor. Open theoutlet tube wide and continue the extraction for7hatauniform rate. To assist in obtaining uniform extraction, it isrecommended that the receiving flask be marked with seven ormore equal volume graduations, so that the rate of extractioncan be easil
34、y gaged, and adjusted by regulating the generationof steam in the boiling-flask. Shake the receiving flask everyhalf hour, to mix the contents, and protect it from the heat ofthe burner during the extraction. Continue the extraction untilthe extract volume reaches the final mark on the flask.9.3 The
35、 addition of three to four drops of toluene to theextract solution is recommended to ensure against mold growthduring the overnight cooling. If the extracted solution is likelyto ferment (for example, myrabolams or divi-divi), add 1 mLof40 % formaldehyde and the extract solution again mixed.9.4 Cool
36、 the solution as directed in Practice D 4904.9.5 Where, as in 8.1, the tannin content of the material is solow that the maximum quantity of sample which can beextracted if the apparatus fails to give a solution containing4.00 6 0.25 g of tannin per litre, reduce the quantity of hidepowder to be used
37、 in the determination of non-tannins in TestMethod D 6401 proportionately.10. Keywords10.1 extraction; tannin; tannin analysis; vegetable tannin;vegetable tannin analysisASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin
38、 this standard. 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 mus
39、t be reviewed 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 the
40、responsible 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
41、, 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 6405 99 (2009)3
