1、Designation: E544 10Standard Practices forReferencing Suprathreshold Odor Intensity1This standard is issued under the fixed designation E544; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pa
2、rentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These practices are designed to outline a preferredmeans for referencing the odor intensities of a material in thesuprathreshold region.1.2 The gen
3、eral objective is to reference the odor intensityrather than other odor properties of a sample.1.3 These practices are designed to reference the odorintensity on the ASTM Odor Intensity Referencing Scale ofany odorous material. This is done by a comparison of the odorintensity of the sample to the o
4、dor intensities of a series ofconcentrations of the reference odorant, which is 1-butanol(n-butanol).1.4 The method by which the reference odorant vapors areto be presented for evaluation by the panelists is specified. Themanner by which the test sample is presented will depend onthe nature of the s
5、ample, and is not defined herein.1.5 Test sample presentation should be consistent with goodstandard practice (1)2and should be explicitly documented inthe test report.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.7 This
6、 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 use. See Annex A1 forspecif
7、ic safety data.2. Referenced Documents2.1 ASTM Standards:3D1292 Test Method for Odor in Water3. Terminology3.1 ASTM odor intensity referencing scaleseries of1-butanol dilutions used to establish which concentrationexhibits an odor intensity matching that of the sample.3.2 concentrationseries of conc
8、entrations of 1-butanol inodorless air, nitrogen, or the water diluent, made to specificreference dilutions which serve as the reference scale, volumebasis, of 1-butanol diluted air or in water. In the latter case, thetemperature of the solution during the test should be reported.3.3 dynamic scalere
9、ference scale in which vapor dilutionsare prepared by continuous mixing of vapors of 1-butanol withan odorless gas, such as air, to yield constant dilutions of vaporin the gas.3.4 panelistsindividuals who compare the odor intensityof the sample to the reference scale. These individuals shouldbe able
10、 to do this with a consistency described in 5.5.3.5 perceived (sensory) odor intensityintensity of an odorsensation which is independent of the knowledge of theodorant concentration.3.6 samplematerial in any form exhibiting an odor thatneeds to be measured.3.7 static scalereference scale in which di
11、lutions of1-butanol in water are prepared in flasks and presented for odorintensity comparison from the flasks.3.8 suprathreshold odor intensityperceived (sensory) in-tensity of the odor in that intensity region in which the odor isclearly experienced.4. Summary of Practice4.1 The reference odorant
12、used to generate an odor intensityscale is 1-butanol (n-butanol). The reasons for its selection aresummarized in Appendix X1. A geometric progression scalewith a ratio of 2 is recommended, that is, a scale in which eachreference dilution differs in its 1-butanol concentration fromthe preceding dilut
13、ion by a factor of 2.4.2 Two procedures, A and B, are described in theserecommended practices. They differ in the method by whichthe diluted 1-butanol vapors are prepared.NOTE 1The relationships between the odor intensity of 1-butanolconcentrations in air and in water have not been evaluated. Transl
14、ation ofProcedure B data to the numerical values of Procedure A is not possibleat this time.1These practices are under the jurisdiction ofASTM Committee E18 on SensoryEvaluation and are the direct responsibility of Subcommittee E18.04 on Fundamen-tals of Sensory.Current edition approved Nov. 1, 2010
15、. Published December 2010. Originallyapproved in 1975. Last previous edition approved in 2004 as E544 99 (2004).DOI: 10.1520/E0544-10.2The boldface numbers in parentheses refer to the list of references at the end ofthese recommended practices.3For referenced ASTM standards, visit the ASTM website,
16、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.
17、2.1 In Procedure A, hereafter referred to as the dynamicscale method, a dynamic-dilution apparatus is used. This isequipped with a series of sniffing ports from which constantconcentrations of 1-butanol emerge at constant volumetric flowrates in air.4.2.2 In Procedure B, hereafter referred to as the
18、 static-scalemethod, a series of Erlenmeyer flasks containing knownconcentrations of 1-butanol in water is used.4.3 The odor of the sample is matched, ignoring differencesin odor quality, against the odor intensity reference scale of1-butanol by a panel yielding at least eight independentjudgments.
19、Panelists report that point in the reference scalewhich, in their opinion, matches the odor intensity of theunknown.4.4 The independent judgments of the panelists are aver-aged geometrically (see 7.4) with respect to the 1-butanolconcentrations of the indicated matching points. Results arereported a
20、s an odor intensity, in parts per million, of 1-butanolin air (ProcedureA) or water (Procedure B) on theASTM OdorIntensity Referencing Scale. When water is used as a diluent,the temperature of the reference scale solutions during the testmust be reported.4.5 The odor intensity equivalent values whic
21、h are obtainedmay then be used to compare the relative intensities of samplegroups. These values are reference values and are not related tothe odor intensities by a simple proportionality coefficient (see8.2).5. Procedure ADynamic-Scale Method5.1 Reagents:5.1.1 1-butanol (n-butanol), the reference
22、odorant, withrequired purity 99+ mol % by gas chromatography. Also shallbe free of strong odorous impurities.5.1.2 DiluentNonodorous room or cylinder air.5.2 Preparation of Dynamic Scale:5.2.1 Prepare the 1-butanol airflow mixtures in an olfacto-meter apparatus as follows: Pass air over an expanded
23、surfaceof 1-butanol in order to produce a saturated vapor at a knownambient temperature. Temperatures should be ambient in orderto avoid condensation in the airflow lines. Air becomessaturated (98+ %) at flow rates up to 60 mL/min when passedover a surface of 1-butanol that is 120 mm long by 10 mm w
24、idein a 13-mm inside diameter glass tube which is held in ahorizontal position. Saturated vapor prepared by bubbling airthrough 1-butanol is less desirable since the bubbles burst atthe surface and produce droplets. In such methods of vaporgeneration, glass wool filter, operating at the same tempera
25、tureas the 1-butanol liquid sample, must be used to remove thedroplets. Obtain concentrations of vapor below saturation bydiluting the saturated vapor with additional volumes of air.5.2.2 If air, such as pumped ambient air which containswater vapor is used, replace the 1-butanol in the saturation tu
26、beevery 2 to 3 h; otherwise it will become diluted by theabsorption of water which will lower the vapor pressure of1-butanol, and will result in a lower odorant concentration atthe sniffing ports.5.2.3 An adequate concentration range for most applicationsis between 5 and 2000 ppm of 1-butanol in air
27、. Above 2000ppm, the odor intensity is too strong for accurate judgment.Below 5 ppm, the odor is too close to the threshold limit forpanelists to make accurate judgments.5.2.4 The temperature of 1-butanol in the saturation tubeshould be noted at the start and kept constant during the test. Itshould
28、be within the range of comfortable room temperatures.5.2.5 The rate of dynamic delivery of air carrying diluted1-butanol vapor from sniffing ports should be 160 6 20mL/min from a port with a cross-section of 400 to 500 mm2,resulting in a nominal linear flow rate of 300 mm/min. A ratethat is too slow
29、 allows the stimulus to be diluted withincreasing amounts of room air. A rate that is too fast creates amechanical sensation in the nose which complicates the odorintensity judgment.5.2.6 An example of a dynamic dilution apparatus, called adynamic olfactometer, is diagrammed in Fig. X1.1 and itsoper
30、ation is explained, in Appendix X4.5.3 Reference Concentrations:5.3.1 This practice is intended to establish, on a continuousppm 1-butanol scale, that ppm value which best corresponds inits odor intensity to the odor intensity of the sample. Since sucha scale is technically difficult, the one design
31、ed consists of aseries of discrete concentration points at sniffing ports continu-ously delivering known concentrations of 1-butanol vapor inair.5.3.2 A geometric progression scale of concentrations isused, in which each reference port differs in its 1-butanolconcentration from the preceding port by
32、 a factor of 2. It wouldhave been desirable to select and always use the same ppmvalues for the same ports, however, this would require verycomplex flow adjustment systems. Although the ppm valuesdelivered by the scale ports change with temperature, theyremain in the same ratio to each other, and th
33、us still permit theintensity equivalence point to be easily found.5.3.3 The scale points are arranged systematically, in theorder of increasing concentrations, and are numbered inascending integers, from 1 for the lowest concentration of1-butanol.5.3.4 The matching points normally used are the scale
34、points, or positions between the scale points, but can also bethose points beyond either end of the scale.5.4 Test RoomThe test room must be well-ventilated,essentially odor-free, and comfortable. In order to avoid bias,waiting panelists should not observe or learn the judgments ofthe panelist curre
35、ntly matching the odor intensity of the sampleto the scale (1, 2).5.5 Odor Panel:5.5.1 NumberThe number of panelists should be eight ormore, to permit elementary statistical tests on their judgments.A smaller number of panelists may be used with replicatejudgments to increase the total to eight or m
36、ore. It is importantwhen obtaining replicate data that all bias is removed. Precau-tions such as separate sessions and recoding are recommended(1).5.5.2 SelectionSpecial training is not needed but precau-tions must be taken in the selection of the panelists (3). Anindividual with insufficient sensit
37、ivity to detect the odor of 10ppm of 1-butanol in air should not be a panelist. Also, someindividuals have been observed to experience difficulty inE544 102matching odor intensities. Prospective panelists can bescreened by having them repeatedly match the odor intensity ofa known concentration of 1-
38、butanol vapor to the 1-butanolreference scale. Those whose standard deviation in repeatedtesting exceeds 1.5 scale steps should not be used in the panel.Periodic retesting of panelists may be advisable.5.6 Judgment Procedure:5.6.1 Panelists are instructed on the nature of the 1-butanolodor intensity
39、 reference scale. They are told that the ports arenumbered beginning with No. 1, which represents the weakestodor and that the odors increase systematically in intensity withincreasing port identification numbers.5.6.2 Panelists are instructed to smell the unknown sampleand then to smell the scale,
40、beginning with its weakest end, andmatch the unknown to the scale, ignoring differences in theodor quality. They are permitted to check and recheck theunknown against the scale any number of times and should notbe hurried or biased by others in any manner.5.6.3 Panelists are advised that they may re
41、port one of thescale points as the best match, or else may report that the bestmatch occurs between two adjacent points, for example, theunknown is stronger than scale point No. 7, but weaker thanscale point No. 8.5.6.4 Panelists should be advised that the odor may also beweaker than the weakest poi
42、nt of the scale, or stronger than thestrongest point of the scale.5.6.5 When his judgment is within scale limits, the panelistshould make sure that the selected position is a good match,that is, that the next lower concentration of 1-butanol indeedsmells weaker than the unknown, and that the next hi
43、gherconcentration indeed smells stronger.5.6.6 Panelists report the matching point in terms of the portidentification number. When the best match is a positionbetween the scale points, such as between port Nos. 7 and 8,the half-number, 7.5, is used.5.6.7 During repeated smelling of one or more sampl
44、es orscale points, olfactory adaptation (fatigue) occurs, renderingthe sense of smell less sensitive. However, the relative positionof the unknown with respect to the scale is not undulyinfluenced unless the rates of adaptation to 1-butanol and to thesample are very different. The adaptation rate to
45、 1-butanol hasbeen reported to be average when compared to other odorants(4). Therefore, the complication that may result from differ-ences in the adaptation rate to the unknown and to 1-butanol isminimized by selecting 1-butanol as the reference odorant.5.6.8 Because of the olfactory adaptation dis
46、cussed in 5.6.7,a panelist may find that after judging at higher odor intensitypoints on the scale, he may have difficulty in detecting odor atthe lowest points of the scale. A rest of 2 to 5 min will usuallycorrect this effect.5.6.9 Panelists may differ in the amount of time required torender a jud
47、gment. The panelist should be allowed to proceedat a rate comfortable to him.As many as six test stimuli can behandled by a panel of nine in a 1-h session.6. Procedure BStatic-Scale Method6.1 The reference odorant is 1-butanol, (see 5.1.1). Thediluent is distilled water that is odor-free.NOTE 2If di
48、luent other than water is used, equivalent ppm (vol/vol)values will not exhibit matching odor intensities because of differences inmolecular weights, densities, and the activity coefficients of 1-butanol indifferent solvents. Use of other solvents is therefore not recommended.6.2 Follow the procedur
49、es outlined in Section 5, except for5.2.6.3 Preparation of Static Scale:6.3.1 Prepare solutions of 1-butanol in water, using pipetsand volumetric flasks, following the usual laboratory proce-dures for solution preparation.6.3.2 ProcedurePlace the reference sniffing solutions intostandard 500-mL wide-mouth, conical Erlenmeyer flasks (seeTest Method D1292). The volume of solution should be 200mL and should be replaced by new solutions after a maximumperiod of 2 h. Between sniffings, cover the top of each flaskwith aluminum foil in order to assure equilibration between
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