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Yes, silica gel can be modified to make its adsorption more specific. E.G., epichlorohydrin dimethyl amine copolymer (Epi-DMA) can be used to make silica gel effective for adsorbing anionic dyes.


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The primary reference for this type of data is the article by Li [1]. Snyder cites this paper as the primary source for UV cutoff values ("Ref 7" on the screenshot below) [2, p. 299]: References Li, J. B. Signal-to-Noise Optimization in HPLC UV Detection. LC GC 1992, 10 (11), 856–864. Snyder, L. R.; Kirkland, J. J.; Glajch, J. L. Practical HPLC ...


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I offer the following explanation for the fragments of the mass spectrum of methyl salicylate (1, m/z 152). Loss of methoxy radical affords acylium ion 2 (m/z 121). Subsequent loss of a proton from 2 gives rise to the base peak 6-oxomethylidenecyclohexa-2,4-dien-1-one (3). Loss of carbon monoxide from 3 produces carbene 4, which rearranges to cyclopenta-2,4-...


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The short answer: Do not rely on the SIM trace alone. Amplify the representation of the trace about the TIC (total ion current) until you see a reasonable peak intensity at the same retention time as in your SIM traces (perhaps a time spectrum, but not a mass spectrum). Then integrate with the peak-shaped cursor (currently shown in the magenta coloured ...


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Neat or pure for organic chemists has a different meaning for analytical chemists. What does your manufacturer label say? 100% pure methyl salicylate? That is not possible. It must have closely related impurities. Did you try a thin layer chromatography experiment with this sample? There is no concept of 100% pure substance in analytical chemistry, ...


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