[rose9090]

1.   you have an HPLC system with 250 x 4.6 mm column. You are using 2 ml/min flow rate and 25 ul sample injection volume. What flow rate and sample volume would you use for  the following columns:
a.   150 x 4.5 mm
b.   250 x 2 mm
c.   100 x 1 mm




2.   Selectivity of the separation of benzene and toluene in reversed-phase HPLC on C-18 type column with 80/20 acetonitrile/water eluent is 2.0. What will be the separation selectivity if the eluent composition will be changed to 60/40 acetonitrile/water?




3.   You were asked to evaluate the results of GPC analysis PMMA (poly{methyl methacrylate}) polymer. Separation was made on PLGel universal column (styrene-divinylbenzene 100 – 10^7 separation range), RI detection, and eluent – THF, calibration by polystyrene standards. Weigh and number average values were calculated directly from chromatogram. Are Mw and Mn values correct? Explain why.

[Dan]

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