ASTM E1790-2004(2016)e1 Standard Practice for Near Infrared Qualitative Analysis《近红外定性分析的标准实施规程》.pdf
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1、Designation: E1790 04 (Reapproved 2016)1Standard Practice forNear Infrared Qualitative Analysis1This standard is issued under the fixed designation E1790; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial change was made in Subsection 6.6.3 in April 2016.1. Scope1.1 This practice covers the use of near-infrared (NIR)spectroscopy for t
3、he qualitative analysis of liquids and solids.The practice is written under the assumption that most NIRqualitative analyses will be performed with instruments de-signed specifically for this region and equipped with comput-erized data handling algorithms. In principle, however, thepractice also app
4、lies to work with liquid samples usinginstruments designed for operation over the ultraviolet (UV),visible, and mid-infrared (IR) regions if suitable data handlingcapabilities are available. Many Fourier Transform Infrared(FTIR) (normally considered mid-IR instruments) have NIRcapability, or at leas
5、t extended-range beamsplitters that allowoperation to 1.2 m; this practice also applies to data fromthese instruments.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 thesa
6、fety 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.2. Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to M
7、olecular SpectroscopyE1252 Practice for General Techniques for Obtaining Infra-red Spectra for Qualitative AnalysisE1655 Practices for Infrared Multivariate QuantitativeAnalysis3. Terminology3.1 DefinitionsFor definitions of general terms and sym-bols pertaining to NIR spectroscopy and statisticalco
8、mputations, refer to Terminology E131.3.2 Definitions of Terms Specific to This Standard:3.2.1 interactance, nthe phenomenon whereby radiantenergy entering the surface of a material is scattered by thematerial back to the surface, but at a different portion of thesurface.3.2.1.1 DiscussionThis diffe
9、rs from diffuse reflectance,where the returning radiation exits the same portion of thesurface of the material as the illuminating radiation entered.3.2.2 training sample (otherwise called a “referencesample” or “standard”), na quantity of material of knowncomposition or properties, or both, present
10、ed to an instrumentfor measurement in order to find relationships between themeasurements and the composition or properties, or both, ofthe sample.3.2.2.1 DiscussionThis term is typically used in conjunc-tion with computerized methods for ascertaining the relation-ships.Training samples for quantita
11、tive analysis (also called“calibration samples,” as in Practices E1655) have differentrequirements than training samples used for qualitativeanalysis.4. Significance and Use4.1 NIR spectroscopy is a widely used technique for quan-titative analysis, and it is also becoming more widely used forthe ide
12、ntification of organic materials, that is, qualitativeanalysis. In general, however, the concept of qualitative analy-sis as used in the NIR spectral region differs from that used inthe mid-IR spectral region in that NIR qualitative analysisrefers to the process of automated comparison of the spectr
13、a ofunknown materials to the spectra of known materials in orderto identify the unknown. This approach constitutes a librarysearch method in which each user generates his own library.4.2 Historically, NIR spectroscopy as practiced with classi-cal UV-VIS-NIR instruments using methods similar to those
14、described in Practice E1252 was not considered to be a strongtechnique for qualitative analysis. Although the positions and1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.11 on Multiv
15、ariate Analysis.Current edition approved April 1, 2016. Published June 2016. Originallyapproved in 1996. Last previous edition approved in 2010 as E1790 04(2010).DOI: 10.1520/E1790-04R16E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servi
16、ceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1intensities of absorption bands in specific wavelength ra
17、ngeswere used to confirm the presence of certain functional groups,the spectra were not considered to be specific enough to allowunequivocal identification of unknown materials. A few impor-tant libraries of NIR spectra were developed for qualitativepurposes, but the lack of suitable data handling f
18、acilitieslimited the scope of qualitative analysis severely. Furthermore,earlier work was limited almost entirely to liquid samples.4.3 Currently, the mid-IR procedure of deducing the struc-ture of an unknown material by method of analysis of thelocations, strengths, and positional shifts of individ
19、ual absorp-tion bands is generally not used in the NIR.4.4 With the development of specialized NIR instrumentsand mathematical algorithms for treating the data, it becamepossible to obtain a wealth of information from NIR spectrathat had hitherto gone unused. While the mathematical algo-rithms descr
20、ibed in this practice can be applied to spectral datain any region, this practice describes their application to theNIR.4.5 The application of NIR spectroscopy to qualitativeanalysis in the manner described is relatively new, and proce-dures for this application are still evolving. The application o
21、fchemometric methods to spectroscopy has limitations, and thelimitations are not all defined yet since the techniques arerelatively new. One area of concern to some scientists is theeffect of low-level contaminants. Any analytical methodologyhas its detection limits, and NIR is no different in this
22、regard,but neither would we expect it to be any worse. Since therelatively broad character of NIR bands makes it unlikely thata contaminant would not overlap any of the measuredwavelengths, the question would only be one of degree:whether a given amount of contaminant could be detected. Theuser must
23、 be aware of the probable contaminants he is liable torun into and account for the possibility of this occurring,perhaps by including deliberately contaminated samples in thetraining set.5. General5.1 NIR qualitative analysis is conducted by comparison ofNIR absorption spectra of unknown materials w
24、ith those ofknown reference materials. Since the absorption bands of manysubstances of interest are less distinctive in the NIR than in themid-IR spectral region, the analytical capability of the tech-nique relies heavily on the accuracy of the absorption mea-surements and the relationship of the re
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