1、Designation: E 1866 97 (Reapproved 2007)Standard Guide forEstablishing Spectrophotometer Performance Tests1This standard is issued under the fixed designation E 1866; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 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 This guide covers basic procedures that can be used todevelop spectrophotometer performance tests. The guide isintended t
3、o be 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 E 275, E 925, E 932, E 958, E 1421,or E 1683 that exist for measuring performance of specifictype
4、s of spectrophotometers. Instead, this guide is intended toprovide guidelines in how similar practices should be devel-oped when specific practices do not exist for a particularspectrophotometer type, or when specific practices are notapplicable due to sampling or safety concerns. This guide canbe u
5、sed to develop performance tests for on-line processspectrophotometers.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
6、checks ofspectrophotometer 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.
7、1.4 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 use.2. Referenced D
8、ocuments2.1 ASTM Standards:2E 131 Terminology Relating to Molecular SpectroscopyE 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-etersE 387 Test Method for Estimating Stray Radiant PowerRatio of Dispersive Spectrophotometers by the Opaqu
9、eFilter MethodE 925 Practice for Monitoring the Calibration ofUltraviolet-Visible Spectrophotometers whose SpectralSlit Width does not Exceed 2 nmE 932 Practice for Describing and Measuring Performanceof Dispersive Infrared SpectrometersE 958 Practice for Measuring Practical Spectral Bandwidthof Ult
10、raviolet-Visible SpectrophotometersE 1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared (FT-MIR) Spectrom-eters: Level Zero and Level One TestsE 1655 Practices for Infrared Multivariate QuantitativeAnalysisE 1683 Practice for Testing the Performance of ScanningRa
11、man Spectrometers3. Terminology3.1 DefinitionsFor terminology relating to molecularspectroscopic methods, refer to Terminology E 131.3.2 Definitions of Terms Specific to This Standard:3.2.1 action limit, nthe limiting value from an instrumentperformance test, beyond which the spectrophotometer isexp
12、ected to produce potentially invalid results.3.2.2 check sample, na single pure compound, or aknown, reproducible mixture of compounds whose spectrum isconstant 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 s
13、pectrum 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 spectrophotometer perfor-mance test in which the spectrum of a check or test sample isanalyzed using a multivariate model, and the results of theanal
14、ysis are compared to historical results for prior analyses ofthe same sample.1This 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
15、 approved Dec. 1, 2007. Published December 2007. Originallyapproved in 1997. Last previous edition approved in 2002 as E 1866 - 97 (2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
16、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.3.2.5 level one (1) test, na simple series of measurementsdesigned to provide quantitative data on various a
17、spects 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 instrumentperformance and provide a da
18、tabase to determine instrumentperformance over time.3.2.7 optical reference filter, nan optical filter or otherdevice which can be inserted 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
19、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 samples 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
20、 the long term.4. Significance and Use4.1 If ASTM Committee E13 has not specified an appropri-ate test procedure for a specific type of spectrophotometer, orif the sample specified by a Committee E13 procedure isincompatible with the intended spectrophotometer operation,then this guide can be used t
21、o develop practical performancetests.4.1.1 For spectrophotometers which are equipped with per-manent or semi-permanent sampling accessories, the testsample specified in a Committee E13 practice may not becompatible with the spectrophotometer configuration. For ex-ample, for FT-MIR instruments equipp
22、ed with transmittance orIRS flow cells, tests based on polystyrene films are impractical.In such cases, these guidelines suggest means by which therecommended test procedures can be modified so as to beperformed on a compatible test material.4.1.2 For spectrophotometers used in process measure-ments
23、, the choice of test materials may be limited due toprocess contamination and safety considerations. These guide-lines suggest means of developing performance tests based onmaterials which are compatible with the intended use of thespectrophotometer.4.2 Tests developed using these guidelines are int
24、ended toallow the user to compare the performance of a spectropho-tometer on any given day with prior performance. The tests areintended to uncover malfunctions or other changes in instru-ment operation, but they are not designed to diagnose orquantitatively assess the malfunction or change. The tes
25、ts arenot intended for the comparison of spectrophotometers ofdifferent manufacture.5. Test Conditions5.1 When conducting the performance 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 b
26、efore the commencement of any measure-ments.5.1.1 If possible, the optical configuration used for measure-ments of test and check samples should be identical to that usedfor normal operations. If identical optical configurations arenot possible, the user should recognize that the performancetests ma
27、y not measure the performance of the entire instru-ment.5.1.2 Data collection and computation conditions shouldgenerally be identical to 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
28、 database.6. Samples Used for Performance Testing6.1 The sample used for performance testing is chosen to becompatible with the spectrophotometer configuration, and toprovide spectral features which are adequate for the tests beingperformed.6.1.1 The sample used for performance testing shouldgeneral
29、ly be in the same physical state (gas, liquid, or solid) asthe samples to be analyzed during normal operation of thespectrophotometer.6.1.2 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 f
30、or performance is chosen such thatits spectrum is similar to the spectra which will be collectedduring normal operation.6.1.4 The sample used for performance testing should haveseveral significant absorbances (0.3 absorbance 1.0) acrossthe spectral range used for normal operation of the spectropho-t
31、ometer.6.1.5 In order to adequately determine the photometriclinearity of the instrument, the peak absorbance for at least oneabsorption band of the sample should be similar to andpreferably slightly greater than the largest absorbance expectedfor samples measured during normal operation.6.2 Check S
32、amplesCheck samples are generally used forconducting performance tests. Check samples are single purecompounds or mixtures of compounds 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
33、stable over long periods of time. In preparingmixtures, components should be accurately pipetted orweighed at ambient temperature. It is recommended thatmixtures be independently verified for composition prior touse.6.2.2 While mixtures can be used as check samples, theirspectra may be adversely aff
34、ected by temperature sensitiveinteractions that may manifest themselves by wavelength(frequency) and absorbance changes.6.3 Test SamplesA 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 per
35、formance testing. The test sample must be stored inbulk quantities in controlled conditions such that the material isstable over time.6.3.1 Since test samples are often complex mixtures whichcannot be synthetically reproduced, they can only be used forperformance testing for limited time periods. If
36、 test samples areused for this purpose, collection of historical data on a new testsample should be initiated before previous test samples areE 1866 97 (2007)2depleted. It is recommended that new test samples be analyzedsequentially with old test samples at least 15 times before theyare used to repl
37、ace the old test sample. The 15 analyses mustbe performed over a time period that does not exceed onemonth in duration.6.4 Optical FiltersAn optical reference filter is an opticalfilter or other optical device located in the spectrophotometeror in a fiber optic sample probe which produces an absorpt
38、ionspectrum which is known to be constant over time. This filtermay be automatically inserted into the optical path to allowinstrument performance 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
39、 the probe is inconvenient, precluding the use ofcheck or test samples for routine instrument performancetesting.6.4.2 If an optical filter is used routinely to check or correctthe spectral data collection or computation, then the same filteris preferably not used for instrument performance testing.
40、 If thesame filter is used, then the part of the filter spectrum used inthe performance testing should preferably differ from that partused to check or correct the instrument. For example, polysty-rene filters are used to standardize (continuously check andcorrect) the wavelength scale of some dispe
41、rsive NIR spectro-photometers. For such systems, polystyrene filters are prefer-ably not to be employed for wavelength stability performancetesting. If polystyrene filters are used, then the peaks used forwavelength stability testing should be different from those usedfor standardizing the wavelengt
42、h scale.7. Univariate Measures of SpectrophotometerPerformance7.1 Energy Level TestsEnergy level tests are intended todetect changes in the radiant power in the spectrophotometerbeam. Decreases in energy levels may be associated withdeterioration of the spectrophotometer source, with contami-nation
43、or misalignment of optical surfaces in the light path, orwith malfunctions of the detector.7.1.1 For single beam spectrophotometers where back-ground and sample spectra are measured separately at differenttimes, energy level tests are generally conducted on a back-ground spectrum. For double beam sp
44、ectrophotometers wherethe ratio of background and sample beam intensities is mea-sured directly, energy levels can be measured if it is possible 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 thi
45、rd of the spectral range. The frequencies (wave-lengths) at which energy levels are measured should be chosento avoid interferences due to atmospheric components (forexample, absorptions of water vapor and carbon dioxide) andfrom interferences due to optical components (for example,OH absorptions in
46、 SiO2cells and fibers). Preferably, regionswhere the background spectrum is relatively flat and slowlyvarying should be used for this test.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) win
47、dow. Typi-cally, the intensity at five points centered on the test frequencyare averaged.7.2 Photometric Noise TestsPhotometric noise is mea-sured at the same frequencies (wavelengths) used for theenergy level tests. Preferably, photometric noise tests areconducted on a 100 % line spectrum. Alternat
48、ively, photomet-ric noise tests may be conducted on the spectrum of a check ortest sample at regions where the spectrum is relatively flat 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
49、, a 100 % line spectrum is obtained by ratioing twosuccessive background measurements to obtain a transmittancespectrum. If, during normal operation of the spectrophotom-eter, backgrounds are collected with a reference material in theoptical path, then this same configuration should be used forperformance testing. Photometric noise calculations are pref-erably done directly on the transmittance spectrum. Alterna-tively, the transmittance spectrum may be converted to anabsorption spectrum by taking the negative log10before thephotometric noise calculations.7.2.2 For double
