ASTM E685-1993(2005) Standard Practice for Testing Fixed-Wavelength Photometric Detectors Used in Liquid Chromatography《液相色谱法用固定波长光度探测装置试验的标准实施规程》.pdf
《ASTM E685-1993(2005) Standard Practice for Testing Fixed-Wavelength Photometric Detectors Used in Liquid Chromatography《液相色谱法用固定波长光度探测装置试验的标准实施规程》.pdf》由会员分享,可在线阅读,更多相关《ASTM E685-1993(2005) Standard Practice for Testing Fixed-Wavelength Photometric Detectors Used in Liquid Chromatography《液相色谱法用固定波长光度探测装置试验的标准实施规程》.pdf(7页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: E 685 93 (Reapproved 2005)Standard Practice forTesting Fixed-Wavelength Photometric Detectors Used inLiquid Chromatography1This standard is issued under the fixed designation E 685; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f 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 This practice is intended to serve as a guide for thetesting of the performance of a photomet
3、ric detector (PD) usedas the detection component of a liquid-chromatographic (LC)system operating at one or more fixed wavelengths in the range210 to 800 nm. Measurements are made at 254 nm, if possible,and are optional at other wavelengths.1.2 This practice is intended to describe the performance o
4、fthe detector both independently of the chromatographic system(static conditions) and with flowing solvent (dynamic condi-tions).1.3 For general liquid chromatographic procedures, consultRefs (1-9).21.4 For general information concerning the principles, con-struction, operation, and evaluation of li
5、quid-chromatographydetectors, see Refs (10 and 11) in addition to the sectionsdevoted to detectors in Refs (1-7).1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety
6、problems, 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:3E 275 Practice for Describing and M
7、easuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-etersE 682 Practice for Liquid Chromatography Terms and Re-lationships3. Terminology3.1 Definitions:3.1.1 absorbance calibration, nthe procedure that verifiesthat the absorbance scale is correct within 65%.3.1.2 drift, nthe
8、 average slope of the noise envelopeexpressed in absorbance units per hour (AU/h) as measuredover a period of 1 h.3.1.3 dynamic, nunder conditions of a flow rate of 1.0mL/min.3.1.4 linear range, nofaPD, the range of concentrationsof a test substance in a mobile phase over which the responseof the de
9、tector is constant to within 5 % as determined from thelinearity plot specified below and illustrated in Fig. 1. Thelinear range should be expressed as the ratio of the highestconcentration to the minimum detectable concentration or thelowest linear concentration, whichever is greatest.3.1.5 long-te
10、rm noise, nthe maximum amplitude in AUfor all random variations of the detector signal of frequenciesbetween 6 and 60 cycles per hour (0.1 and 1.0 cycles per min).3.1.5.1 DiscussionIt represents noise that can be mistakenfor a late-eluting peak. This noise corresponds to the observednoise only and m
11、ay not always be present.3.1.6 minimum detectability, nofaPD, that concentrationof a specific solute in a specific solvent that results in a detectorresponse corresponding to twice the static short-term noise.3.1.7 response time (speed of output), nthe detector, thetime required for the detector out
12、put to change from 10 to 90 %of the new equilibrium value when the composition of themobile phase is changed in a stepwise manner, within the linearrange of the detector.3.1.7.1 DiscussionBecause the detector volume is verysmall and the transport rate is not diffusion dependent, theresponse time is
13、generally fast enough to be unimportant. It isgenerally comparable to the response time of the recorder anddependent on the response time of the detector electrometer1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and is the direct responsibility of Subcommitt
14、ee E13.19 on Chroma-tography.Current edition approved Sept. 1, 2005. Published September 2005. Originallyapproved in 1979. Last previous edition approved in 2000 as E 685 93 (2000).2The boldface numbers in parentheses refer to the list of references at the end ofthis practice.3For referenced ASTM st
15、andards, 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 Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken
16、, PA 19428-2959, United States.and on the recorder amplifier. Factors that affect the observedresponse time include the true detector response time, elec-tronic filtering, and system band-broadening.3.1.8 short-term noise, nthe maximum amplitude, peak topeak, in AU for all random variations of the d
17、etector signal ofa frequency greater than one cycle per minute.3.1.8.1 DiscussionIt determines the smallest signal de-tectable by a PD, limits the precision attainable in quantitationof trace-level samples, and sets the lower limit on linearity.This noise corresponds to the observed noise only.3.1.9
18、 static, nunder conditions of no flow.4. Significance and Use4.1 Although it is possible to observe and measure each ofthe several characteristics of a detector under different andunique conditions, it is the intent of this practice that acomplete set of detector specifications should be obtainedund
19、er the same operating conditions. It should also be notedthat to completely specify a detectors capability, its perfor-mance should be measured at several sets of conditions withinthe useful range of the detector. The terms and tests describedin this practice are sufficiently general that they may b
20、e usedregardless of the ultimate operating parameters.4.2 Linearity and response time of the recorder or otherreadout device used should be such that they do not distort orotherwise interfere with the performance of the detector. Thisrequires adjusting the gain, damping, and calibration in accor-dan
21、ce with the manufacturers directions. If additional elec-tronic filters or amplifiers are used between the detector and thefinal readout device, their characteristics should also first beestablished.5. Noise and Drift5.1 Test ConditionsPure, degassed methanol of suitablegrade4shall be used in the sa
22、mple cell. Air or nitrogen shall beused in the reference cell if there is one. Nitrogen is preferredwhere the presence of high-voltage equipment makes it likelythat there is ozone in the air. Protect the entire system fromtemperature fluctuations because these will lead to detectabledrift.5.1.1 The
23、detector should be located at the test site andturned on at least 24 h before the start of testing. Insufficientwarm-up may result in drift in excess of the actual value for thedetector.5.2 Methods of Measurement:5.2.1 Connect a suitable device (Note 1) between the pumpand the detector to provide at
24、 least 75 kPa (500 psi) backpressure at 1.0 mL/min flow of methanol. Connect a shortlength (about 100 mm) of 0.25-mm (0.01-in.) internal-diameterstainless steel tubing to the outlet tube of the detector to retardbubble formation. Connect the recorder to the proper detectoroutput channels.NOTE 1Sugge
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