1、Designation:E165798(Reapproved 2011)Standard Practice forTesting Variable-Wavelength Photometric Detectors Used inLiquid Chromatography1This standard is issued under the fixed designation E1657;the number immediately following the designation indicates the year oforiginal adoption or,in the case of
2、revision,the year of last revision.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 practice covers the testing of the performance of avariable-wavelength photometric detector(VWPD)
3、used as thedetection component of a liquid-chromatographic(LC)systemoperating at one or more wavelengths in the range 190 to 800nm.Many of the measurements are made at 254 nm forconsistency with Practice E685.Measurements at other wave-lengths are optional.1.2 This practice is intended to describe t
4、he performance ofthe 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,construction,operation,andevaluatio
5、nofliquid-chromatography detectors,see Refs(10,11)in addition to thesections devoted 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 con
6、cerns,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:3E685 Practice for Testing Fixed-Wavelength
7、 PhotometricDetectors Used in Liquid Chromatography3.Terminology3.1 Definitions:3.1.1 absorbance calibrationthe procedure that verifiesthat the absorbance scale is correct within 65%.3.1.2 driftthe average slope of the noise envelope ex-pressed in absorbance units per hour(AU/h)as measured overa per
8、iod of 1 h.3.1.3 dynamicunder conditions of a flow rate of 1.0mL/min.3.1.4 linear rangeof a VWPD,the range of concentrationsof a test substance in a test solvent over which the ratio ofresponse of the detector versus concentration of test substanceis constant to within 5%as determined from the linea
9、rity plotspecified in 7.1.2 and illustrated in Fig.1.The linear rangeshould be expressed as the ratio of the upper limit of linearityobtained from the plot to either(a)the lower linearconcentration,or(b)the minimum detectable concentration,ifthe minimum detectable concentration is greater than the l
10、owerlinear concentration.3.1.5 long-term noisethe maximum amplitude in AU forall 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 correspond
11、s to the observednoise only and may not always be present.3.1.6 minimum detectability of a VWPD,that concentra-tion of a specific solute in a specific solvent that results in adetector response corresponding to twice the static short-termnoise.3.1.6.1 DiscussionThe static short-term noise is a mea-s
12、urement of peak-to-peak noise.A statistical approach to noisesuggests that a value of three times the rms(root-mean-square)noise would insure that any value outside this range would notbe noise with a confidence level of greater than 99%.Sincepeak-to-peak noise is approximately five times the rms no
13、ise(12),the minimum detectability defined in this practice is amore conservative estimate.1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.19 on Separation Science.Current edition appr
14、oved Nov.1,2011.Published December 2011.Originallyapproved in 1994.Last previous edition approved in 2006 as E1657 98(2006).DOI:10.1520/E1657-98R11.2The boldface numbers in parentheses refer to the list of references at the end ofthis practice.3For referenced ASTM standards,visit the ASTM website,ww
15、w.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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.7 respon
16、se time(speed of output)the detector,thetime required for the detector output to change from 10%to90%of the new equilibrium value when the composition ofthe mobile phase is changed in a stepwise manner,within thelinear range of the detector.3.1.7.1 DiscussionBecause the detector volume is verysmall and the transport rate is not diffusion dependent,theresponse time is generally fast enough to be unimportant.It isgenerally comparable to the response time of the recorder anddependent on the respons
