SINGLE-SAMPLE LINEARITY TEST FOR WAVELENGTH SCANNING DETECTORS IN LIQUID-CHROMATOGRAPHY

With the present demands on good laboratory practice, it is essential to verify that the analytical instrument is in a good condition. This may be done by a system suitability test before each use of the instru ment where the performance of the instrument is estimated for a given analytical method, or as an instrument check routine at regular interv als. The linearity of a spectrophotometric detector compounds the cond ition of the lamp, the cell, the electronic circuitry, and the stray l ight into one figure. Thus the detector linearity test may be used as a method that covers multiple sources of possible errors. Hence qualit y testing of detectors can be made routinely every time an analytical method is used with the same injected standard as in the method. A met hod for linearity tests of scanning liquid chromatography detectors is developed. This method only requires the injection of one sample in t he chromatographic system. The injected sample must result in a peak t hat spans the expected linear range of the detector. The peak must be free from other overlapping peaks. Then the linearity is estimated by principal components analysis of the spectra in the sample peak.