1、Designation: E 204 98 (Reapproved 2002)Standard Practices forIdentification of Material by Infrared AbsorptionSpectroscopy, Using the ASTM Coded Band and ChemicalClassification Index1This standard is issued under the fixed designation E 204; the number immediately following the designation indicates
2、 the year oforiginal adoption or, in the case of revision, the 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 These practices describe a data system generat
3、ed from1955 through 1974. It is in world-wide use as the largestpublicly available data base. It is recognized that it does notrepresent the optimum way to generate a new data base withthe most modern computerized equipment.1.2 These practices describe procedures for identification ofindividual chem
4、ical substances using infrared absorption spec-troscopy and band indexes of spectral data. Use of absorptionspectroscopy for qualitative analysis has been described bymany (1-8),2but the rapid matching of the spectrogram of asample with a spectral data in the literature by use of a bandindex system
5、designed for machine sorting was contributed byKuentzel (9). It is on Kuentzels system that theASTM indexesof absorption spectral data are based.1.3 Use of these practices requires, in addition to a record-ing spectrometer and access to published reference spectra, theencoded data and suitable data
6、handling equipment.31.4 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
7、 use.2. Referenced Documents2.1 ASTM Standards:E 168 Practices for General Techniques of Infrared Quanti-tative Analysis4E 932 Practice for Describing and Measuring Performanceof Dispersive Infrared Spectrometers4E 1252 Practice for General Techniques for QualitativeInfrared Analysis43. Summary of P
8、ractices3.1 Arepresentative sample of the material to be analyzed isseparated into its individual components, if required, and eachcomponent is introduced into a suitable sample cell or matrix,mainly according to its physical state. The spectrum is re-corded over a characterizing range. The choice o
9、f spectralrange and instrument is dictated by a general consideration ofthe chemical nature of the sample (3-5). A note is made of thespectral positions of prominent absorption bands and, option-ally, of known chemical and physical properties of the material.The qualitative chemical composition of t
10、he material may thenbe identified by searching the coded data file for compoundshaving matching characteristics. Details on searching proce-dures are available elsewhere.5Details of the code are in thefollowing sections.4. Apparatus4.1 Infrared SpectrophotometerAspectrophotometer withcapabilities eq
11、uivalent to an instrument with a rock salt prismoperated under parameters compatible with Analytical Spectra(8, 10) and with wavelength accuracy to 0.05 m by compari-son with the indene spectrum in Practice E 932.4.2 Laboratory procedures for obtaining spectra are de-scribed in Refs (3-5) and in Pra
12、ctices E 168, and E 1252.4.3 Data-Handling EquipmentIt is possible to convertdata on the ASTM magnetic tape to IBM cards, and to usesorters or collators to manipulate the data. However, the file islarge and it is more efficient, and with good software, moreeffective, to use computers. These may be e
13、ither dedicated ortime-shared. Thus, the minimum equipment requirement is a1These practices are under the jurisdiction of ASTM Committee E-13 onMolecular Spectroscopy and are the direct responsibility of Subcommittee E13.03on Infrared Spectroscopy.Current edition approved Dec. 10, 1998. Published Au
14、gust 1999. Originallypublished as E 20462T. Discontinued 1998. Reinstated December 1998.2The boldface numbers in parentheses refer to the list of references at the end ofthese practices.3The ASTM Infrared Spectral Index, AMD 33 and its supplements may bepurchased in the form of magnetic tapes, from
15、Sadtler Research Labs., Inc., 3316Spring Garden St., Philadelphia, PA 19104.4Annual Book of ASTM Standards, Vol 03.06.5Publicly available systems are as follows: IRGO, Chemir Labs., 761 W.Kirkham, St. Louis, MO 63122; SPIR (Canada only), National Research Council,100 Sussex Dr., Ottawa, Ontario, Can
16、ada K1A OR6.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sputer, a program, and the coded data (and either batchprocessing facilities) or a teletypewriter or terminal withmodem for accessing these resources5for interactive searches.5. In
17、dex5.1 The index data on approximately 145 000 spectra areavailable on magnetic tape. The main absorption bands of eachspectrum are coded to the nearest 0.1 m.5.2 In addition to the code for spectral data of chemicalsubstances, there are codes for chemical-structure classifica-tion, empirical formul
18、a, melting or boiling point, and serialnumber reference. Other codes include data on sample state,wavelength intervals of strongest bands, and no-data areas. Fora given substance, the coded spectral data are almost invariablyunique as is the pattern for coded chemical structure andphysical propertie
19、s. Variables may be searched in any desiredcombination to locate a standard spectrum similar to that of asample of unknown composition, to correlate type of structurewith absorption band positions, to locate spectra of compoundshaving given structural features in common, and in other waysthat are to
20、o numerous to include here.5.3 Spectral and chemical data from the users own labora-tory may be coded in a compatible system from details givenin subsequent sections.5.4 Molecular formula-name tabulations comprise comple-mentary data systems for use in conjunction with the spectralband codes and che
21、mical classification tapes. These carry themolecular formulas, chemical names, and reference serialnumbers for the compounds included in the indexes describedin 5.1 and 5.2. The tapes are commercially available and theindexes have been published in book form as alphabetical,numerical, and molecular
22、formula indexes (11,12,13). Thesebooks enable one to determine the name of the compoundinvolved from a knowledge of the serial number of a spectro-gram or to locate a published standard spectrogram for acompound when the name is known. The serial-number listingpermits one to obtain the names of poss
23、ible solutions toanalytical problems from spectra serial numbers produced bysearch operations even though complete files of standardspectra (as listed in Table 1) are not at hand. Often the name ofthe compound together with other available information willsuffice; however, it is desirable to have as
24、 many standardspectra as feasible on hand for detailed study and comparison,because positive identification depends upon matching theunknown spectrum with one from published material or oneobtained from a bona fide sample of the compound. Themolecular formula and alphabetical indexes are useful fora
25、ccessing band data for a suspected answer to an unknown.6. General6.1 The system described below is designed to handle thespectral absorption data obtained in the spectral range from 2to 16 m, and the system provides for a band-position codingresolution of 0.1 m.6.2 The original coding was on an IBM
26、 card format. Thenumerical values therefore correspond to columns and rows.See Fig. 1.6.3 Columns 1 through 15 are used for coding absorptionband positions.6.4 The chemical classification code is in columns 32through 57, and columns 58 through 62 provide for coding thenumber of C, N, O, and S atoms
27、in the compound underconsideration. A melting or boiling point is coded in 63 to 65.The rest of the card provides space for the private use ofindividual laboratories and the identification of the source ofthe coded data. The codes concerned with each of these areasare discussed separately.CODING OF
28、INFRARED ABSORPTION BANDS(COLUMNS 1 THROUGH 25)7. Codes for Absorption Band Positions7.1 Columns 1 to 15 of “A” Cards (Note)Coding is donein terms of wavelength in micrometres. From columns 1through 15, the column number is taken as the whole numbervalue of the absorption band, and the fractional pa
29、rt is roundedto the nearest 0.1 m (values ending in five hundredths areconsidered as next higher tenths) and the number correspond-ing to the 0.1 m value is added to the number of the column.Thus a band at 7.38 m is coded to correspond to position 4 incolumn 7, for a value of 7.4. The coding resolut
30、ion of 0.1 mhas been found to be adequate for searching and correlatingpublished spectra.NOTE 1“A” is the designation for rock salt region infrared data (see18.4).7.2 Columns 1 to 25 of “G” for Far-InfraredThe codingof far-infrared absorption bands is done in terms of wavelengthin micrometres. The w
31、hole number value of the band positionTABLE 1 Catalogs of Spectrograms Covered by ASTM PunchedCards Indexing Infrared Absorption DataA API Research Project 44AB Users own file of spectrogramsBC Sadtler catalog of spectrogramsCD NRC-NBS file of spectrogramsDE LiteratureF Documentation of Molecular Sp
32、ectroscopyEG Coblentz Society SpectrogramsFH Chemical Manufacturers Association (CMA)GJ Infrared Data Committee of JapanHK Aldrich Library of Infrared SpectraI, 1970 EditionAAmerican Petroleum Institute, Research Project 44, Infrared and UltravioletSpectral Data, Texas Agricultural and Mechanical Co
33、llege, College Station, TX,1943 to date. Loose-leaf.BUsers are encouraged to submit spectrograms (or the pure compound in somecases) to one of the other organizations listed. It is unlikely that any individuallaboratory can code its spectral data and punch cards at the cost of the ASTMcards (about o
34、ne cent each).CStandard and Commercial Spectra, Sadtler Research Laboratories, 3316Spring Garden St., Philadelphia, Pa. 19104. Loose-leaf. The Sadtler organizationalso offers a “Spec-Finder” book method of matching spectrograms with those inits catalog.DNational Research Council-NBS Committee on Spe
35、ctral Absorption Data,National Bureau of Standards, Washington, D. C. 20025. Card file.EThe DMS System, Butterworth Scientific Publications, London WC2. Distrib-uted in U. S. by Butterworth, Inc., 7235 Wisconsin Ave., Washington, D. C. 20014.FCoblentz Society Spectra, sold by Sadtler Research Labora
36、tories. 3316 SpringGarden St., Philadelphia, Pa. 19104 and The Coblentz Society, Inc., P.O. Box9952, Kirkwood, MO 63122.GChemical Manufacturers Association (CMA) 1825 Connecticut Ave., N. W.,Washington, D. C. Loose-leaf. Spectra are no longer available from CMA.HInfrared Data Committee of Japan, San
37、yo Shuppan Doeki Co., Inc., HoyuBldg., 8, 2-chrome, Takaracho, Chuo-ku, Tokyo, Japan. Card file distributed in U.S. by Preston Technical Abstracts Co., 1718 Sherman Ave., Evanston, Ill.IThe Aldrich Library of Infrared Spectra, Aldrich Chemical Co., 940 N. St. PaulSt., Milwaukee, Wis. 53233.E 204 98
38、(2002)2is obtained by adding 10 to the column number and the nearesttenth of a micrometre is represented by the decimal value to thenearest tenth. Thus, a band at 18.57 m is coded as 8.6.7.3 To indicate the range of data covered by the spectro-gram, an “x” code is coded for each column that codes as
39、pectral range where no data are available. This is to distin-guish such regions from those in the spectrogram that havebeen examined and found to contain no bands of sufficientintensity to code, or to mark those regions where the spectraldata are obscured by strong solvent bands. Additionally, a “y”
40、code is added to each column that indexes a very strong band.The coding of such strong bands is limited to a very few,usually about three, which may be expected to persist in thespectrum of a considerably diluted sample of the material. Useof such codes may be made in the analysis of mixtures wherei
41、ndividual components may be present in relatively low con-centrations so that only the strongest bands are readily detect-able.8. Criteria for the Selection of Bands to be Coded8.1 Experience has shown that it is not desirable to code allof the bands of most spectra. Major and medium strength bandsa
42、re coded to identify the compounds uniquely. However,coding of too many weak bands minimizes the effectiveness ofnegative searching, which is valuable for mixtures. Therefore,the selection of which bands to code and which to omit requiressome judgment; and because of the nature of publishedspectrogr
43、ams, the judging can be guided only by rather flexiblerules. Several factors enter into the determination of thestrength of an absorption band, and what may be a good set offactors for the production of an excellent spectrogram from onematerial is not necessarily a good set to provide a spectrogramf
44、rom another material. Moreover, the quality of publishedspectra varies widely and any system of coding absorptionbands must allow for making the best possible use of all suchdata.8.2 As a general rule, bands selected to be coded have anabsorbance ratio with the strongest band in the spectrogram of1:
45、10 or more. This means that when the strongest band hasbetween 1 and 5 % transmittance, bands are coded which have70 % or less transmittance as measured from a reasonablyadjacent background (not necessarily at 100 % transmittance);or if the strongest band is between 5 and 20 % transmittance,bands ar
46、e coded which have 80 % or less transmittance asmeasured from a reasonably adjacent background. Thus, to becoded, a band stands out from its adjacent background, at leaston one side, by 20 to 30 % transmittance on the chart.Therefore,“ shoulders” and weak bands on the sides of strongbands are not co
47、ded. Likewise, bands whose percent transmit-tance may be as low as 60 to 50 as read from the chart, butwhich extend from backgrounds having transmittance values of80 to 70 %, are not coded. Some examples are provided in Fig.2.8.3 Searching absorption band data is much the same ascoding the bands. Fi
48、rst, the spectrogram of the unknownmaterial should have its strongest bands between 1 and 20 %transmittance since it is to be compared with data coded on thatbasis. Then one proceeds by two different methods dependingupon whether the unknown is a single component or is amixture of two or more compon
49、ents in roughly equivalentamounts. In the former case, positive searching on the bands isin order, while the latter case requires that negative inputs beincluded in the search request. Each method is discussedbriefly in Sections 9 and 10.8.4 The optimum combination of searching techniques de-pends upon the computer algorithm used. Instructions specificfor each program should be followed.59. Positive Searching for Individual Spectra9.1 In this method, the search data are selected with theexpectation that all or most of the bands in the unknownspectrogram are c
