1、Designation: D3495 10 (Reapproved 2015)Standard Test Method forHexane Extraction of Leather1This standard is issued under the fixed designation D3495; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers the quantitative extraction
3、of alltypes of leather with hexane. This test method does not applyto wet blue.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
4、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 use.2. Referenced Documents2.1 ASTM Standards:2D2813 Practice for Sampling Leather for Physical andChemical TestsD37
5、90 Test Method for Volatile Matter (Moisture) ofLeather by Oven Drying3. Significance and Use3.1 This test method measures the amount of hexane-soluble lubricant present in all types of leather. Adequatelubrication prevents abrasion of leather fibers during flexing.This lubrication is generally obta
6、ined from the fat liquor addedat the tannery. Some lubrication is also obtained from naturalgrease produced during the life of the animal.4. Apparatus4.1 Analytical Balance.4.2 Soxhlet Apparatus, consisting of a boiling flask, extrac-tion tube, and condenser.4.3 Forced Circulating Air Oven, capable
7、of maintaining thespecified temperature.4.4 Electric Hot Plate.4.5 Extraction Thimbles, fat-free, cellulose, Alundum, orfritted.4.6 Absorbent Cotton, fat-free.4.7 Steam Bath.5. Reagent5.1 Hexane, ACS Reagent Grade conforming to the follow-ing requirements:5.1.1 Color (APHA)10 max.5.1.2 Density (g/mL
8、) at 25C0.687 max.5.1.3 Boiling Range1 to 95 mL, not more than 4.0C.5.1.4 Residue After Evaporation0.001 % max.5.1.5 Acidity (as CH3COOH) To pass test (limit 0.002 %).5.1.6 Sulfur Compounds (as S)0.005 % max.5.1.7 ThiopheneTo pass test.NOTE 1This reagent grade hexane is generally a mixture of severa
9、lisomers of hexane (C6H14), predominantly n-hexane and methylcyclopen-tane (C6H12).6. Test Specimens6.1 The leather shall be sampled in accordance with MethodD2813. Leather test specimens shall be obtained from thecomposite sample prepared by random sampling, cutting, andmixing equal portions of lea
10、ther representing the lot that isbeing analyzed. The well-mixed leather pieces shall be groundin a mill (Wiley or equal) having a No. 5 (4-mm) sieve. Theground leather that passes through this 4-mm sieve shall bemixed well and used as the composite sample.7. Procedure7.1 Determine the moisture conte
11、nt of the composite samplefrom which the ground leather for hexane extraction is taken inaccordance with Test Method D3790. Determine the weight ofthe ground leather taken from the composite sample formoisture content at the same time and under the same ambientconditions as the weight of the ground
12、leather taken for hexaneextraction.1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.06 on Chemical Analysis.Current edition approved Dec. 1, 2015. Published December 2015. Originallyapproved in 1976. Last previous editio
13、n approved in 2010 as D3495 10. DOI:10.1520/D3495-10R15.2For 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.Copyr
14、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17.2 Weigh5gofground leather taken from the composite tothe nearest 0.001 g and record this value as W1. Loosely packthis material in an appropriately sized extraction thimble andcover with a
15、pad of fat-free cotton. Place the loaded thimble inthe Soxhlet extraction tube. Dry an extraction flask in an ovenfor1hat1006 2C, cool in a desiccator, and weigh to thenearest 0.001 g. Record this value as W2. Fill the flaskapproximately two-thirds full with hexane, assemble theapparatus, circulate
16、the water through the condenser, and heatthe flask until the extraction of the leather has continued for aminimum of 50 cycles. If the Soxhlet drips continuouslyinstead of cycling, extract the leather for a minimum of 5 husing maximum heat. At the end of the extraction period,remove the flask contai
17、ning the extraction solvent and drive offthe hexane. When 10 to 20 mL of hexane remain, heat gentlyon a steam bath until the odor of the solvent can no longer bedetected. Facilitate the removal of the hexane by utilizing avacuum or a gentle stream of filtered (oil- and water-free) air.After the hexa
18、ne has been removed, dry the flask containingthe extracted matter in a forced circulating air oven at 100 62C, for 2 h, cool to room temperature in a desiccator andweigh. Continue drying for successive 2-h periods until con-stant weight is obtained. When successive weighings vary byless than 6 0.005
19、 g, consider the weight constant. Record thisweight to the nearest 0.001 g as W3. No more than threesuccessive 2-h drying periods shall be allowed. If constantweight has not been obtained after the third drying, the resultsof the second drying period shall be reported.8. Calculation8.1 Calculate the
20、 percentage of hexane-soluble matter, on amoisture-free basis, as follows:Hexane 2 soluble matter, % 5W32 W2W13100 2 % moisture!1003100(1)where:W1= original weight of extracted leather,W2= weight of extraction flask, andW3= weight of extraction flask and hexane-soluble matter.9. Report9.1 Report the
21、 hexane-soluble matter in the leather as theaverage value obtained from the test results to nearest 0.01 %.9.2 State that the results are calculated on a moisture-freebasis.10. Precision and Bias10.1 Interlaboratory Test Data3An interlaboratory testwas run in 1972 in which each of 7 laboratories tes
22、ted duplicatespecimens from each of 15 different types of leather. Alllaboratories tested the following leathers: chamois, yellowlace, crust sheepskin, crust goatskin, vegetable-strap leather,chrome-retan side leather, vegetable-skirting leather,vegetable-retan side leather, latigo-lace leather, whi
23、te-laceleather, suede sheepskin, horsehide (finished), white-sideleather, chrome-split leather, and silicone-treated militaryleather. The components of variance for hexane-soluble matterexpressed as standard deviations were calculated to be:Within 2 laboratory single operator! (2)component 2 0.14 pe
24、rcentage pointsBetween 2 laboratory component 2 0.41 percentage points (3)10.2 PrecisionFor the components of variance reported in9.1, two averages of two observations each of hexane solublematter should be considered significantly different at the 95 %probability level if the difference equals or e
25、xceeds thefollowing critical differences:Within 2 laboratory single operator! precision 0.59 percentage points(4)Between 2 laboratory precision 1.41 percentage points see Note 3!(5)NOTE 2The critical differences were calculated using t = 1.960,which is based on infinite degrees of freedom.NOTE 3The
26、calculated values of the critical differences should beconsidered to be a general statement particularly with respect to between-laboratory precision. Before a meaningful statement can be made abouttwo specific laboratories, the amount of statistical bias, if any, betweenthem must be established, wi
27、th each comparison being based on recentdata obtained on randomized specimens from one sample of the materialto be tested. The interlaboratory test showed that for certain leatherscontaining more than 18 % hexane-soluble matter the between-laboratorycritical difference could be as high as 3 percenta
28、ge points.10.3 BiasNo justifiable statement on bias can be made,since the true value of hexane-soluble matter cannot beestablished by an accepted reference method.11. Keywords11.1 extractables; extraction; fat liquor; hexanesolublelubricant; lubricationASTM International takes no position respecting
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33、 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:/ data have been filed atASTM Headquarters and may be obtained byrequesting Research Report RR: D-31-1003.D3495 10 (2015)2
