1、Designation: E544 10E544 18Standard PracticesPractice 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.
2、 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 These practices areThis practice is designed to outline a preferred means for referencing the odor intensities of a materialin the s
3、uprathreshold region.1.2 The general objective is to reference the odor intensity rather than other odor properties of a sample.1.3 These practices areThis practice is designed to reference the odor intensity on the ASTM Odor Intensity Referencing Scaleof any odorous material. This is done by a comp
4、arison of the odor intensity of the sample to the odor intensities of a series ofconcentrations of thea reference odorant, which isfor example, 1-butanol (n-butanol).1.4 The method by which the reference odorant vapors are to be presented for evaluation by the panelistsassessors is specified.The man
5、ner by which the test sample is presented will depend on the nature of the sample, and is not defined herein.1.5 Test sample presentation should be consistent with good standard practice (1, 2)2 and should be explicitly documented inthe test report.1.6 The values stated in SI units are to be regarde
6、d as standard. No other units of measurement are included in this standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenviron
7、mental practices and determine theapplicability of regulatory limitations prior to use. See Annex A1 for specific safety data.1.8 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Dev
8、elopment of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D1292 Test Method for Odor in Water3. Terminology3.1 ASTM odor intensity referencing scaleseries of 1-butanol d
9、ilutions used to establish which concentration exhibits an odorintensity matching that of the sample.3.2 concentrationseries of concentrations of 1-butanol in odorless air, nitrogen, or the water diluent, made to specificreference dilutions which serve as the reference scale, volume basis, of 1-buta
10、nol diluted air or in water. In the latter case, thetemperature of the solution during the test should be reported.3.2 dynamic scalereference scale in which vapor dilutions are prepared by continuous mixing of vapors of 1-butanol with anodorless gas, such as air, to yield constant dilutions of vapor
11、 in the gas. An example is presentation through an olfactometer.3.4 panelistsindividuals who compare the odor intensity of the sample to the reference scale. These individuals should be ableto do this with a consistency described in 5.5.1 These practices areThis practice is under the jurisdiction of
12、 ASTM Committee E18 on Sensory Evaluation and are the direct responsibility of Subcommittee E18.04 onFundamentals of Sensory.Current edition approved Nov. 1, 2010Oct. 1, 2018. Published December 2010October 2018. Originally approved in 1975. Last previous edition approved in 20042010as E544 99 (2004
13、).E544 10. DOI: 10.1520/E0544-10.10.1520/E0544-18.2 The boldface numbers in parentheses refer to the list of references at the end of these recommended practices.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book o
14、f ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technical
15、ly possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
16、700, West Conshohocken, PA 19428-2959. United States13.5 perceived (sensory) odor intensityintensity of an odor sensation which is independent of the knowledge of the odorantconcentration.3.6 samplematerial in any form exhibiting an odor that needs to be measured.3.3 static scalereference scale in w
17、hich dilutions of 1-butanol in water are prepared in flasks or other suitable containers andpresented for odor intensity comparison from the parison.3.8 suprathreshold odor intensityperceived (sensory) intensity of the odor in that intensity region in which the odor is clearlyexperienced.4. Summary
18、of Practice4.1 The reference odorant used to generate an odor intensity scale is 1-butanol (n-butanol). The reasons for its selection aresummarized in Appendix X1. A geometric progression scale with a ratio of 2 is recommended, that is, a scale in which eachreference dilution differs in its 1-butano
19、l concentration from the preceding dilution by a factor of 2.4.2 Two procedures, A and B, are described in these recommended practices. They differ in the method by which the diluted1-butanol vapors are prepared.In this method, a series of known concentrations of 1-butanol is used.NOTE 1The relation
20、ships between the odor intensity of 1-butanol concentrations in air and in water have not been evaluated. Translation of ProcedureB data to the numerical values of Procedure A is not possible at this time.4.2.1 In ProcedureA, hereafter referred to as the dynamic scale method, a dynamic-dilution appa
21、ratus is used. This is equippedwith a series of sniffing ports from which constant concentrations of 1-butanol emerge at constant volumetric flow rates in air.4.2.2 In Procedure B, hereafter referred to as the static-scale method, a series of Erlenmeyer flasks containing knownconcentrations of 1-but
22、anol in water is used.4.3 The odor of the sample is matched, ignoring differences in odor quality, against the odor intensity reference scale of1-butanol by a panel yielding at least eight independent judgments. Panelists panel. Assessors report that point in the referencescale which, in their opini
23、on, matches the odor intensity of the unknown.4.4 The independent judgments of the panelistsassessors are averaged geometrically (see 7.46.3) with respect to the 1-butanolconcentrations of the indicated matching points. Results are reported as an odor intensity, in parts per million, of 1-butanol in
24、 air(Procedure A)(dynamic method) or water (Procedure B)(static method) on the ASTM Odor Intensity Referencing Scale. Whenwater is used as a diluent, the temperature of the reference scale solutions during the test must be reported.4.5 The odor intensity equivalent values which are obtained may then
25、 be used to compare the relative intensities of samplegroups. These values are reference values and are not related to the odor intensities by a simple proportionality coefficient (see8.2Appendix X2).5. Procedure ADynamic-Scale Method5.1 Reagents:5.1.1 1-butanol (n-butanol), the reference odorant, w
26、ith required purity 99+ mol % by gas chromatography. Also shall bechromatography and free of strong odorous impurities.5.1.2 DiluentDiluent: Nonodorous room or cylinder air.5.1.2.1 For a “Static Method”, utilizing solutions in a suitable container, 1-butanol is prepared in an aqueous solution usingo
27、dor-free water.NOTE 1If diluent 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 in different solvents. Use of other solvents is therefore not recomme
28、nded.5.1.2.2 For a “Dynamic Method”, utilizing an olfactometer, nonodorous room air, carbon filtered air, or cylinder air arenecessary.5.2 Preparation of Static Scale:5.2.1 Prepare solutions of 1-butanol in water, using pipets and volumetric flasks, following usual laboratory procedures forsolution
29、preparation.5.2.2 ProcedurePlace the reference sniffing solutions into a suitable glass flask or jar. The volume of solution should beselected to not fill more than 14 of the sniffing container headspace. Between sniffing, cover the top of each container in order toassure equilibration between the s
30、olution and the air head-space above it. The container should be gently swirled by each assessorprior to each sniffing in order to assure equilibrium.5.2.3 The temperature of the reference solutions during the test should be ambient and kept constant during the test.5.2.4 The odor threshold of 1-but
31、anol in water is 2.5 ppm at 21C (3).The useful concentration range for the static scale is abovethis value but does not extend to the solubility limit of 7.08 % of 30C (70 800 ppm) (4). At concentrations close to the solubilitylimit, excess 1-butanol may separate from the solution with temperature c
32、hange. If this occurs the odor becomes equivalent to thatof pure 1-butanol.E544 1825.2.5 Considerable latitude as to the selection of concentrations is allowed. To go from the saturation point to the thresholdrequires 16 steps, assuming that each succeeding mix is one half of the preceding concentra
33、tion (70 800; 35 400; 17 000; 8850ppm; etc.). Solutions stronger than 20 000 ppm of 1-butanol exhibit an odor that is too intense for most comparisons.5.2.6 The most useful concentration range is approximately between 10 and 20 000 ppm, and may be covered by twelve flaskscontaining 10 ppm in flask N
34、o. 1, 20 ppm in flask No. 2, etc. These flasks constitute the static scale.5.2.7 The scale points are arranged systematically, in the order of increasing concentrations, and are numbered in ascendingintegers, from 1 for the lowest concentration of 1-butanol.5.3 Preparation of Dynamic Scale:5.3.1 Pre
35、pare the 1-butanol airflow mixtures in an olfactometer apparatus as follows: Pass air over an expanded surface of1-butanol in order to produce a saturated vapor at a known ambient temperature. Temperatures should be ambient in order to avoidcondensation in the airflow lines. Air becomes saturated (9
36、8+ %) at flow rates up to 60 mL/min when passed over a surface of1-butanol that is 120 mm long by 10 mm wide in a 13-mm inside diameter glass tube which is held in a horizontal position.Saturated vapor prepared by bubbling air through 1-butanol is less desirable since the bubbles burst at the surfac
37、e and producedroplets. In such methods of vapor generation, glass wool filter, operating at the same temperature as the 1-butanol liquid sample,must be used to remove the droplets. Obtain concentrations of vapor below saturation by diluting the saturated vapor withadditional volumes of air.utilizing
38、 a known concentration of butanol from a prepared gas cylinder or by a headspace over liquidbutanol.5.2.2 If air, such as pumped ambient air which contains water vapor is used, replace the 1-butanol in the saturation tube every2 to 3 h; otherwise it will become diluted by the absorption of water whi
39、ch will lower the vapor pressure of 1-butanol, and willresult in a lower odorant concentration at the sniffing ports.5.3.2 An adequate concentration range for most applications is between 5 will depend on olfactometer design, for example,presentation air flow rate. For most applications a range betw
40、een 200 ppb and 2000 ppm of 1-butanol in air.Above 2000 ppm, theodor intensity is too strong for accurate judgment. Below 5 ppm, the odor is too close to the threshold limit for panelists to makeaccurate judgments.air is most useful.5.2.4 The temperature of 1-butanol in the saturation tube should be
41、 noted at the start and kept constant during the test. It shouldbe within the range of comfortable room temperatures.5.2.5 The rate of dynamic delivery of air carrying diluted 1-butanol vapor from sniffing ports should be 160 6 20 mL/min froma port with a cross-section of 400 to 500 mm2, resulting i
42、n a nominal linear flow rate of 300 mm/min.Arate that is too slow allowsthe stimulus to be diluted with increasing amounts of room air. A rate that is too fast creates a mechanical sensation in the nosewhich complicates the odor intensity judgment.5.2.6 An example of a dynamic dilution apparatus, ca
43、lled a dynamic olfactometer, is diagrammed in Fig. X1.1 and its operationis explained, in Appendix X4.5.4 Reference Concentrations:5.4.1 This practice is intended to establish, on a continuous ppm 1-butanol scale, that ppm value concentration which bestcorresponds in its odor intensity to the odor i
44、ntensity of the sample. Since such a continuous scale is technically difficult, the onedesigned a common olfactometer design consists of a series of discrete concentration points at sniffing ports continuouslydelivering known concentrations of 1-butanol vapor in air.5.4.2 Ageometric progression scal
45、e of concentrations is used, in which each reference port differs in its 1-butanol concentrationfrom the preceding port by a factor of 2. It would have been desirable to select and always use the same ppm values for the sameports, however, this would require very complex flow adjustment systems. Alt
46、hough the ppm values delivered by the scale portschange with temperature, they remain in the same ratio to each other, and thus still permit the intensity equivalence point to beeasily found.5.4.3 The scale points are arranged systematically, in the order of increasing concentrations, and are number
47、ed in ascendingintegers, from 1 for the lowest concentration of 1-butanol.5.3.4 The matching points normally used are the scale points, or positions between the scale points, but can also be those pointsbeyond either end of the scale.5.5 Test RoomThe test room must be well-ventilated, essentially od
48、or-free, and comfortable. In order to avoid bias, waitingpanelistsassessors should not observe or learn the judgments of the panelistassessor currently matching the odor intensity of thesample to the scale (1, 2, 5, 6).5.6 Odor Panel:5.6.1 NumberThe number of panelistsassessors should be eight or mo
49、re, sufficient to permit elementaryproper statistical testson their judgments. A smaller number of panelistsminimum panel of six assessors is recommended. A small number of assessorsmay be used with replicate judgments to increase the total to eight or more. number of responses. It is important when obtainingreplicate data that all bias is removed. Precautions such as separate sessions and recoding are recommended (1).5.6.2 SelectionSpecialExtensive training is not needed but precautions must be taken in the selection of the panelistsassessors(37, 8)
