{"id":26,"date":"2024-04-04T00:39:46","date_gmt":"2024-04-03T21:39:46","guid":{"rendered":"https:\/\/sisu.ut.ee\/lcms_method_validation\/24-identity-confirmation\/"},"modified":"2024-04-04T00:41:46","modified_gmt":"2024-04-03T21:41:46","slug":"24-identity-confirmation","status":"publish","type":"page","link":"https:\/\/sisu.ut.ee\/lcms_method_validation\/24-identity-confirmation\/","title":{"rendered":"2.4. Introduction to identity confirmation"},"content":{"rendered":"

\r\n\tConfirmation of the analyte\u2019s identity is closely related to the selectivity assessment of the method. Validation guidelines usually discuss these topics together and it might be confusing. In case of a\u00a0selectivity assessment, we know where the analyte peak is, or if it is missing. In case of an\u00a0identity confirmation, the problem is reversed \u2013 there is a peak on the chromatogram, and the analyst must provide evidence that this\u00a0peak belongs to the analyte. The information required to collect such evidence is obtained during a validation.\r\n<\/p>\r\n\r\n

\r\n\tThe following evidence is used in chromatographic methods for confirming the identy of an\u00a0analyte:\r\n<\/p>\r\n\r\n

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  1. \r\n\t\tChromatographic retention time. The basic requirement in chromatography is that the retention time of the\u00a0compound must be the same in the standard solution and in the sample. But similar retention time alone does not confirm the identity of the analyte\u00a0as there are potentially many compounds (sample constituents) that may elute at the same (or very similar) retention time.\r\n\t<\/li>\r\n\t
  2. \r\n\t\tSpectrometric methods used for detection can provide evidence that the detected compound is the same as the analyte. UV-Vis and fluorescence detectors are classical spectrometric LC detectors, which provide some information about the structural features of compounds, but UV-Vis and fluorescence spectra are usually not sufficiently characteristic to the analytes for their positive identification. Mass spectrometric techniques, especially high resolution MS and\u00a0tandem MS (MS\/MS), are\u00a0the most powerful methods for identity confirmation.\r\n\t<\/li>\r\n<\/ol>\r\n\r\n

    \r\n\tMost of the validation guidelines consider LC and some recognize the power of MS for identity confirmation. In contrast, ICH is more general and summarizes\u00a0general requirements instead of considering\u00a0specific techniques (LC, spectrophotometry, etc).\u00a0In order to demonstrate that the developed method is able to discriminate between compounds of closely related structures, positive results must be obtained for samples containing the analyte and negative results for samples which do not. Also, negative results must be demonstrated for compounds, which are structurally similar or closely related to an\u00a0analyte. Proper selection of potentially interfering compounds requires scientific judgement, experience and knowledge.\r\n<\/p>\r\n\r\n

    \r\n\tThe following two sections look in more detail at the identity confirmation via retention time and MS, respectively.\r\n<\/p>\r\n\r\n

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