Handbook of Size Exclusion Chromatography and Related ...

Figure 12 Wheat glucans: DRI elution profiles ! raw mass; Wyatt Optilab R 903:
interferometric refractometer at l ¼ 630 nm. SEC system: TosoHaas guard
PWH þ GMPWM þ GMPW6000 þ 5000 þ 4000 þ 3000 (150 7.5 mm); eluent,
0.1 M NaCl(aq) þ 0.005 M Na2CO3(aq) þ NaN3; flow rate, 0.80 mL/min.
constant (DRI cal const) and specific refractive index increment [(srii)l or
(dn/dc)l].
conc ¼ DRI cal const DRI sens
area DRI
(dn=dc) l loop vol
where conc ¼ glucan sample concentration ! [mg/mL], dn/dc ¼ specific
refractive index increment ! [mL/g], loop vol ¼ applied volume of glucan
solution ! [mL], DRI cal const ¼ slope of “conc vs. detector signal” ! [nL/
area], DRI sens ¼ attenuation/amplification factor, and area DRI ¼ integral of
DRI chromatogram within selective separation range.
As illustrated in Fig. 12 for wheat starch glucans, the percentage of
molecular dissolved glucans increases, but, typically remains far away from total
recovery. The missing percentage of 40–70%, however, remains not fixed to the
matrix but forms supermolecular aggregates that elute below the DRI detection
limit superimposed to the molecular dissolved glucans in the selective SEC
separation range and continue to elute for several void volumes. An indication of
© 2004 by Marcel Dekker, Inc.
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