1、Designation: E 1866 97 (Reapproved 2002)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 describes basic procedures that can be usedto develop spectrophotometer performance tests. The guide isintende
3、d to 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 specifict
4、ypes 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 canb
5、e used 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, routi
6、ne 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 manufactu
7、re.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. Reference
8、d Documents2.1 ASTM Standards:E 131 Terminology Relating to Molecular Spectroscopy2E 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-eters2E 387 Test Method for Estimating Stray Radiant PowerRatio of Spectrophotometers by the Opaque Filte
9、r Method2E 925 Practice for the Periodic Calibration of Narrow Band-Pass Spectrophotometers2E 932 Practice for Describing and Measuring Performanceof Dispersive Infrared Spectrometers2E 958 Practice for Measuring Practical Spectral Bandwidthof Ultraviolet-Visible Spectrophotometers2E 1421 Practice f
10、or Describing and Measuring Performanceof Fourier Transform Infrared (FT-IR) Spectrometers:Level Zero and Level One Tests2E 1655 Practice for Infrared, Multivariate, QuantitativeAnalysis2E 1683 Practice for Testing the Performance of ScanningRaman Spectrometers23. Terminology3.1 DefinitionsFor termi
11、nology 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 isexpected to produce potentially invalid results.3.2.2 chec
12、k 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 spectrum of a check or test sample iscompared against hi
13、storical 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 theanalysis are compared to historical results for prior analy
14、ses ofthe same sample.3.2.5 level one (1) test, na simple series of measurementsdesigned to provide 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 perform
15、ance, which can be done in a few minutes,designed to visually detect significant changes in instrument1This 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 Spe
16、ctroscopy.Current edition approved Sept. 10, 2002. Published September 2002.2Annual Book of ASTM Standards, Vol 03.06.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.performance and provide a database to determine instrumentperforman
17、ce 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 of a check or test sample in a performa
18、nce 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 the long term.4. Significance and Use4
19、.1 If ASTM Committee E-13 has not specified an appro-priate test procedure for a specific type of spectrophotometer,or if the sample specified by a Committee E-13 procedure isincompatible with the intended spectrophotometer operation,then this guide can be used to develop practical performancetests.
20、4.1.1 For spectrophotometers which are equipped with per-manent or semi-permanent sampling accessories, the testsample specified in a Committee E-13 practice may not becompatible with the spectrophotometer configuration. For ex-ample, for FT-MIR instruments equipped with transmittance orIRS flow cel
21、ls, 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, the choice of test materials may b
22、e 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 intended toallow the user to compare th
23、e 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 tests arenot intended for the compariso
24、n 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 before the commencement of any measur
25、e-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 may not measure the performance of the
26、 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 database.6. Samples Used for Perfor
27、mance 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 shouldgenerally be in the same physical state (ga
28、s, 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 for performance is chosen such thatit
29、s 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-tometer.6.1.5 In order to adequately
30、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 SamplesCheck samples are generally us
31、ed 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 stable over long periods of time. In
32、 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 affected by temperature sensitiveintera
33、ctions 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 performance testing. The test sample mu
34、st 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 test samples areused for this purpo
35、se, collection of historical data on a new testsample should be initiated before previous test samples 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 perfo
36、rmed over a time period that does not exceed onemonth in duration.E 1866 97 (2002)26.4 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 absorptionspectrum which is known to be con
37、stant 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 the probe is inconvenient, precludi
38、ng 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. If thesame filter is used, then the
39、 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 dispersive NIR spectro-photometers. For s
40、uch 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 wavelength scale.7. Univariate Measures of Sp
41、ectrophotometerPerformance7.1 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 or misalignment of optical surfaces
42、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 spectrophotometers wherethe ratio of b
43、ackground 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 third of the spectral range. The freque
44、ncies (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 SiO2cells and fibers). Preferably,
45、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) window. Typi-cally, the intensity at fi
46、ve 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. Alternatively, photomet-ric noise tests may
47、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, a 100 % line spectrum is obtained
48、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 ca
49、lculations 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 beam spectrophotometers, a 100 % linespectrum is measured when the two beams are both empty,both contain empty matched cells, or both contain referencesamples in matched cells.7.2.3 Photometric noise is measured by fitting a line to thespectrum over a short spectral region centered on the testfrequency (wavelength). The region should c
