ASTM E685-93 (R2021) pdf free download.Standard Practice for Testing Fixed-Wavelength Photometric Detectors Used in Liquid Chromatography.
1.1 This practice is intended to serve as a guide for the testing of the performance of a photometric detector (PD) used as the detection component of a liquid-chromatographic (LC) system operating at one or more fixed wavelengths in the range 210 nm to 800 nm. Measurements are made at 254 nrn. if possible. and are optional at other wavelengths.
1.2 This practice is intended to describe the performance of the detector both independently of the chrornatographic system (static conditions) and with flowing solvent (dynamic condit 10 fl s).
1.3 For general liquid chromatographic procedures. consult Refs (1_9).2
1 .4 For general information concerning the principles, construction, operation, and evaluation of liquidchromatography detectors, see Refs (10 and 11) in addition to the sections devoted to detectors in Refs (1-7).
3. Terminology
3. 1 Definitions.
3. 1 . 1 absorbance calibration, n—the procedure that verities that the absorbance scale is correct within ±5 %.
3.1.2 drift, n—the average slope of the floise envelope expressed in absorhance units per hour (AU/h) as measured over a period of 1h.
3. 1 .3 dynamic, n—under conditions of a flow rate of 1 .0 mL/min.
3.1.4 linear range, n—of a PD. the range of concentrations of a test substance in a mobile phase over which the response of the detector is constant to within 5 % as determined from the linearity plot specified below and illustrated in Fig. 1. The linear range should he expressed as the ratio of the highest concentration to the minimum detectable concentration or the lowest linear concentration, whichever is greatest.
3. 1 .5 long—term noise, n—the maximum amplitude in AU for all random variations of the detector signal of frequencies between 6 cycles per hour and 60 cycles per hour (0.1 cycles per mm and 1.0 cycles per mm).
3. 1 .5. 1 Discussion—It represents noise that can be mistaken for a late-cluting peak. This noise corresponds to the observed noise only and may not always be present.
3.1.6 minimum detectabiliti n—of a PD, that concentration of a specific solute in a specific solvent that results in a detector response corresponding to twice the static short-term noise.ASTM E685 pdf download.