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this question may not fit in this forum because it's about English, but biochemistry knowledge is required, so please allow me to make this thread.

When you measure the molecular weight of a polymer, you may use polystyrene standards and say "polystyrene equivalent Mw of --- is..." or "the molecular weight relative to polystyrene (standards) is..." I have seen these usages in various articles and documents. The other day, however, I ran into an expression, "the Mw was reduced to polystyrene." I understand that it means the same thing, but my question is, do native speakers really say like this? I googled "reduced to polystyrene" and got many hits, but it seemed many of them were written by Japanese. And when I did the same thing on Google Books, there was only one hit and the "reduced" meant "converted/changed." So my question is, do you say "reduce to polystyrene" in this particular situation, meaning you use polystyrene standards?

Thank you very much!

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  • $\begingroup$ As a native English (American version anyway...) I can't say that "the Mw was reduced to polystyrene" is absolutely wrong but it seems very awkward. I'd use "the Mw was compared to polystyrene" or "the Mw was determined relative to polystyrene." $\endgroup$ – MaxW Mar 30 '16 at 3:26
  • $\begingroup$ Thank you very much! Yes, that's what I wanted to know, if the expression sounds natural or awkward. Thank you :) $\endgroup$ – Cochon noir Mar 31 '16 at 2:44
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Just write what you actually did: You used the calibration curve of your SEC column for polystyrene in solvent xx. Those phrases you cite are meant to sound impressive, but are actually just scientifically wrong, bad English, and therefore stupid.

Nothing gets reduced here like a reduced temperature or a chemical reduction. Also there is no "PS equivalent Mw", because it depends strongly on the solvent. "Relative" is as wrong, because that implies that there is simply a factor between the two scales, while in fact there are two calibration curves, one of which is unknown.

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  • $\begingroup$ Thank you for your comment, but are those phrases really scientifically wrong? For example, "PS-equivalent Mw of Polymer A" means the Mw of Polymer A as determined by using the calibration curve of your SEC column for polystyrene, no? There are two calibration curves elicited under the same conditions ( which means, the same solvent for both) except the object is polystyrene or the unknown analyte. Equivalent (= corresponding to PS standards) and relative (= in relation to PS/ not absolute) sound right to me...? $\endgroup$ – Cochon noir Mar 31 '16 at 3:05
  • $\begingroup$ Those adjectives both imply there is a direct, linear relation. That you cannot know. $\endgroup$ – Karl Apr 1 '16 at 16:40
  • $\begingroup$ It is likely, as i see it, if your sample elutes in the range of retention time/volume where your calibration curve is linear. The slope of the log (Mw)/v_ret should always be similar there. IF your sample coils to an isotropic ball, described by one radius of gyration. $\endgroup$ – Karl Apr 1 '16 at 17:08

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