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 instrument where the performance of the instrument is estimated for a given analytical method, or as an instrument check routine at regular intervals. The linearity of a spectrophotometric detector compounds the condition of the lamp, the cell, the electronic circuitry, and the stray light into one figure. Thus the detector linearity test may be used as a method that covers multiple sources of possible errors. Hence quality testing of detectors can be made routinely every time an analytical method is used with the same injected standard as in the method. A method for linearity tests of scanning liquid chromatography detectors is developed. This method only requires the injection of one sample in the chromatographic system. The injected sample must result in a peak that 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.