1、Designation: E1866 97 (Reapproved 2013)Standard Guide forEstablishing Spectrophotometer Performance Tests1This standard is issued under the fixed designation E1866; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 This guide covers basic procedures that can be used todevelop spectrophotometer performance tests. The guide isintended to b
3、e applicable to spectrophotometers operating inthe ultraviolet, visible, near-infrared and mid-infrared regions.1.2 This guide is not intended as a replacement for specificpractices such as Practices E275, E925, E932, E958, E1421,orE1683 that exist for measuring performance of specific types ofspect
4、rophotometers. Instead, this guide is intended to provideguidelines in how similar practices should be developed whenspecific practices do not exist for a particular spectrophotom-eter type, or when specific practices are not applicable due tosampling or safety concerns. This guide can be used to de
5、velopperformance tests for on-line process spectrophotometers.1.3 This guide describes univariate level zero and level onetests, and multivariate level A and level B tests which can beimplemented to measure spectrophotometer performance.These tests are designed to be used as rapid, routine checks of
6、spectrophotometer performance. They are designed to uncovermalfunctions or other changes in instrument operation, but donot specifically diagnose or quantitatively assess the malfunc-tion or change. The tests are not intended for the comparison ofspectrophotometers of different manufacture.1.4 This
7、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.2. Referenced Documents2
8、.1 ASTM Standards:2E131 Terminology Relating to Molecular SpectroscopyE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible SpectrophotometersE925 Practice for Monitoring the Calibration of Ultraviolet-Visible Spectrophotometers whose Spectral Bandwidthdoes not Exceed 2 nm
9、E932 Practice for Describing and Measuring Performance ofDispersive Infrared SpectrometersE958 Practice for Measuring Practical Spectral Bandwidthof Ultraviolet-Visible SpectrophotometersE1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared (FT-MIR) Spectrom-eters:
10、 Level Zero and Level One TestsE1655 Practices for Infrared Multivariate QuantitativeAnalysisE1683 Practice for Testing the Performance of ScanningRaman Spectrometers3. Terminology3.1 DefinitionsFor terminology relating to molecularspectroscopic methods, refer to Terminology E131.3.2 Definitions of
11、Terms Specific to This Standard:3.2.1 action limit, nthe limiting value from an instrumentperformance test, beyond which the spectrophotometer isexpected to produce potentially invalid results.3.2.2 check sample, na single pure compound, or aknown, reproducible mixture of compounds whose spectrum is
12、constant over time such that it can be used in a performancetest.3.2.3 level A test, na pass/fail spectrophotometer perfor-mance test in which the spectrum of a check or test sample iscompared against historical spectra of the same sample via amultivariate analysis.3.2.4 level B test, na pass/fail s
13、pectrophotometer perfor-mance test in which the spectrum of a check or test sample isanalyzed using a multivariate model, and the results of theanalysis are compared to historical results for prior analyses ofthe same sample.3.2.5 level one (1) test, na simple series of measurementsdesigned to provi
14、de quantitative data on various aspects ofspectrophotometer performance and information on which tobase the diagnosis of problems.3.2.6 level zero (0) test, na routine check of spectropho-tometer performance, which can be done in a few minutes,designed to visually detect significant changes in instr
15、ument1This guide is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.03 on Infrared and Near Infrared Spectroscopy.Current edition approved Jan. 1, 2013. Published January 2013. Originallyapproved in 19
16、97. Last previous edition approved in 2007 as E1866 97 (2007).DOI: 10.1520/E1866-97R13.2For 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 Summar
17、y page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1performance and provide a database to determine instrumentperformance over time.3.2.7 optical reference filter, nan optical filter or otherdevice which can be i
18、nserted into the optical path in thespectrophotometer or probe producing an absorption spectrumwhich is known to be constant over time such that it can beused in place of a check or test sample in a performance test.3.2.8 test sample, na process or product sample, or amixture of process or product s
19、amples which has a constantspectrum for a finite time period and which can be used in aperformance test. Test samples and their spectra are generallynot reproducible in the long term.4. Significance and Use4.1 If ASTM Committee E13 has not specified an appropri-ate test procedure for a specific type
20、 of spectrophotometer, orif the sample specified by a Committee E13 procedure isincompatible with the intended spectrophotometer operation,then this guide can be used to develop practical performancetests.4.1.1 For spectrophotometers which are equipped with per-manent or semi-permanent sampling acce
21、ssories, the testsample specified in a Committee E13 practice may not becompatible with the spectrophotometer configuration. Forexample, for FT-MIR instruments equipped with transmittanceor IRS flow cells, tests based on polystyrene films are imprac-tical. In such cases, these guidelines suggest mea
22、ns by whichthe recommended test procedures can be modified so as to beperformed on a compatible test material.4.1.2 For spectrophotometers used in processmeasurements, the choice of test materials may be limited dueto process contamination and safety considerations. Theseguidelines suggest means of
23、developing performance testsbased on materials which are compatible with the intended useof the spectrophotometer.4.2 Tests developed using these guidelines are intended toallow the user to compare the performance of a spectropho-tometer on any given day with prior performance. The tests areintended
24、 to uncover malfunctions or other changes in instru-ment operation, but they are not designed to diagnose orquantitatively assess the malfunction or change. The tests arenot intended for the comparison of spectrophotometers ofdifferent manufacture.5. Test Conditions5.1 When conducting the performanc
25、e tests, the spectropho-tometer should be operated under the same conditions as willbe in effect during its intended use. Sufficient warm-up timeshould be allowed before the commencement of any measure-ments.5.1.1 If possible, the optical configuration used for measure-ments of test and check sample
26、s should be identical to that usedfor normal operations. If identical optical configurations arenot possible, the user should recognize that the performancetests may not measure the performance of the entire instru-ment.5.1.2 Data collection and computation conditions shouldgenerally be identical to
27、 those used in normal operation.Spectral data used in performance tests should be date and timestamped, and the results of the tests should be stored in ahistorical database.6. Samples Used for Performance Testing6.1 The sample used for performance testing is chosen to becompatible with the spectrop
28、hotometer configuration, and toprovide spectral features which are adequate for the tests beingperformed.6.1.1 The sample used for performance testing shouldgenerally be in the same physical state (gas, liquid, or solid) asthe samples to be analyzed during normal operation of thespectrophotometer.6.
29、1.2 The sample used for performance testing should bephysically and chemically compatible with the samples ana-lyzed during normal operation.6.1.3 The sample used for performance is chosen such thatits spectrum is similar to the spectra which will be collectedduring normal operation.6.1.4 The sample
30、 used for performance testing should haveseveral significant absorbances (0.3 absorbance 1.0) acrossthe spectral range used for normal operation of the spectropho-tometer.6.1.5 In order to adequately determine the photometriclinearity of the instrument, the peak absorbance for at least oneabsorption
31、 band of the sample should be similar to andpreferably slightly greater than the largest absorbance expectedfor samples measured during normal operation.6.2 Check SamplesCheck samples are generally used forconducting performance tests. Check samples are single purecompounds or mixtures of compounds
32、of definite composition.6.2.1 If mixtures are utilized as check samples, they must beprepared in a repeatable manner and, if stored, stored such thatthe mixture is stable over long periods of time. In preparingmixtures, components should be accurately pipetted orweighed at ambient temperature. It is
33、 recommended thatmixtures be independently verified for composition prior touse.6.2.2 While mixtures can be used as check samples, theirspectra may be adversely affected by temperature sensitiveinteractions that may manifest themselves by wavelength(frequency) and absorbance changes.6.3 Test Samples
34、A test sample is a process or productsample or a mixture of process or product samples whosespectrum is expected to be constant for the time period it isused in performance testing. The test sample must be stored inbulk quantities in controlled conditions such that the material isstable over time.6.
35、3.1 Since test samples are often complex mixtures whichcannot be synthetically reproduced, they can only be used forperformance testing for limited time periods. If test samples areused for this purpose, collection of historical data on a new testsample should be initiated before previous test sampl
36、es aredepleted. It is recommended that new test samples be analyzedsequentially with old test samples at least 15 times before theyare used to replace the old test sample. The 15 analyses mustbe performed over a time period that does not exceed onemonth in duration.E1866 97 (2013)26.4 Optical Filter
37、sAn optical reference filter is an opticalfilter or other optical device located in the spectrophotometeror in a fiber optic sample probe which produces an absorptionspectrum which is known to be constant over time. This filtermay be automatically inserted into the optical path to allowinstrument pe
38、rformance tests to be performed.6.4.1 Optical filters are used principally with on-line pro-cess spectrophotometers equipped with fiber optic probes whenremoval of the probe is inconvenient, precluding the use ofcheck or test samples for routine instrument performancetesting.6.4.2 If an optical filt
39、er is used routinely to check or correctthe spectral data collection or computation, then the same filteris preferably not used for instrument performance testing. If thesame filter is used, then the part of the filter spectrum used inthe performance testing should preferably differ from that partus
40、ed to check or correct the instrument. For example, polysty-rene filters are used to standardize (continuously check andcorrect) the wavelength scale of some dispersive NIR spectro-photometers. For such systems, polystyrene filters are prefer-ably not to be employed for wavelength stability performa
41、ncetesting. If polystyrene filters are used, then the peaks used forwavelength stability testing should be different from those usedfor standardizing the wavelength scale.7. Univariate Measures of SpectrophotometerPerformance7.1 Energy Level TestsEnergy level tests are intended todetect changes in t
42、he radiant power in the spectrophotometerbeam. Decreases in energy levels may be associated withdeterioration of the spectrophotometer source, with contami-nation or misalignment of optical surfaces in the light path, orwith malfunctions of the detector.7.1.1 For single beam spectrophotometers where
43、 back-ground and sample spectra are measured separately at differenttimes, energy level tests are generally conducted on a back-ground spectrum. For double beam spectrophotometers wherethe ratio of background and sample beam intensities is mea-sured directly, energy levels can be measured if it is p
44、ossible toblock the sample beam.7.1.2 Energy levels should be measured at at least threefixed frequencies (wavelengths), one each in the upper, middleand lower third of the spectral range. The frequencies (wave-lengths) at which energy levels are measured should be chosento avoid interferences due t
45、o atmospheric components (forexample, absorptions of water vapor and carbon dioxide) andfrom interferences due to optical components (for example,OH absorptions in SiO2cells and fibers). Preferably, regionswhere the background spectrum is relatively flat and slowlyvarying should be used for this tes
46、t.7.1.3 To minimize the effects of photometric noise on theenergy level measurement, it is preferable to average theenergy over a narrow frequency (wavelength) window.Typically, the intensity at five points centered on the testfrequency are averaged.7.2 Photometric Noise TestsPhotometric noise is me
47、a-sured at the same frequencies (wavelengths) used for theenergy level tests. Preferably, photometric noise tests areconducted on a 100 % line spectrum. Alternatively, photomet-ric noise tests may be conducted on the spectrum of a check ortest sample at regions where the spectrum is relatively flat
48、andthe sample absorbance is minimal (0.1).7.2.1 For single beam spectrophotometers where back-ground and sample spectra are measured separately at differenttimes, a 100 % line spectrum is obtained by ratioing twosuccessive background measurements to obtain a transmittancespectrum. If, during normal
49、operation of thespectrophotometer, backgrounds are collected with a referencematerial in the optical path, then this same configuration shouldbe used for performance testing. Photometric noise calcula-tions are preferably done directly on the transmittance spec-trum. Alternatively, the transmittance spectrum may be con-verted to an absorption spectrum by taking the negative log10before the photometric noise calculations.7.2.2 For double beam spectrophotometers, a 100 % linespectrum is measured when the two beams are both empty,both contain empty matched cells, or both
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