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Strictly same retention time means exact same signal in GC (i.e."apparently" same compound). This means you'd have one peak for the mixture as if it was a single compound. On an unknown sample, you might miss the fact that there are two compounds coeluting. To avoid the issue, you would always inject the sample on (at least) two columns with ...


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Have a look at this one from reference (1) [my highlight]: In the simple case, the use of retention data for identification purposes involves merely a comparison between the retention time of an unknown and that of a series of authentic compounds. Since the essential ability of chromatography is to separate substances, a negative conclusion - these two ...


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] Complete overlap (= identical retention) is a regular feature of experimental chromatography with very different compounds and complex mixtures. It just happens when the selectivity happens to be equal to 1.00. You can have one, two, or three different compounds hidden under a single peak and this usually happens in early eluting peaks in all modes of ...


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You have several queries. First of let us look at the gradient method used by the authors. The HPLC gradient for synthetic colorants was 0 min A 100 p. cent, 10 min A 0 p. cent, 14 min A 100 p. cent. The HPLC gradient for natural carmine was 0 min A 80 p. cent, 20 min A 50 p. cent, 23 min A 30 p. cent, 25 min A 30 p. cent Factually, notice the trend in the ...


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ELSD is an acronym for Evaporative Light Scattering Detector. It is used as a quasi-universal detector for HPLC. The first step is the nebulization of the column effluents with a dry gas as you have mentioned. If the column effluents contain any non-volatile analyte, then those will form minute particles. The mintue particles become suspended in the gas ...


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I think there is no perfect answer to this situation. In general when the flow is stopped to any detector in an HPLC experiment, there is a change in baseline, and when the flow is re-started, ghost peaks appear in chromatogram. I am talking about optical detectors such as UV, fluorescence, refractive index etc. Same thing happens in MS and perhaps LC ESI-MS ...


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I sort of feel this is actually more of a mathematical/statistical/modeling related question than traditional chemistry. In essence, one argument is that the sample derived effective API concentration is impacted by possible changes in the particle size distribution due to grinding. Now, there are, in effect, known statistical distributions that address ...


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