inulinase) tohydrolyse fructans into fructoseandglucoseand the released fructose is
measuredbyHPAEC-PAD. The total fructan content of the sample isobtainedby comparing
theareaof the chromatographicpeakof fructose from the samplewith that of a fructose
standard solution. The result is correctedbyusinga correction factor (k) toadapt for water
uptakeduring fructanhydrolysis. A further correction factor (p) takes intoaccount the loss
of the terminal fructoseof reducingFm type fructans (since it hasbeen converted to sorbitol
ormannitol during the reduction stage) or theglucose fromGFn type frucans (sinceglucose
isnotmeasuredduring theHPAEC-PADanalysis). These factors (k&p) areeasily calculated
from theaverageDPof the fructan ingredient.
C.
Apparatus&Materials
(a)
Anion exchange chromatograph (HPAEC) comprising a gradient pumpwith a eluent
degassing (by helium sparging) module, autosampler, pulsed electrochemical
detector working in pulsed amperometric mode (PAD) and a post-column delivery
system.
(b)
Operating conditions – Mobile phase flow rate, 1.0 mL/min; column temperature,
ambient; injectionvolume20μL; post columndelivery flow rate0.6mL/min.
(c)
LC columns – Analytical column, Carbopac PA1 250 x4mm, 10μm particle size ;
Guard column, CarbopacPA1, 50 x4mm
(d)
Analytical balancewith ±0.1mg readability.
(e)
Centrifuge
(f) Vacuum centrifuge
(g)
pHmeter
(h)
Waterbathmaintainedat 80°C (±1°C).
(i)Waterbathmaintainedat 40°C (±0.2°C).
(j)Vortexmixer
(k)
LC injectionvials; 1.6mL,withpre-slit PTFE/silicone septa
(l)Vial inserts; 100μL, glasspulledpoint
D.
Reagents
(m)Milli-Qpurifiedwater, 18MΩ (all references to “water” refer to this).
(n)
Sodiumhydroxide solution, 50% (w/w)
(o)
Sodiumhydroxidepellets,GR for analysis
(p)
Sodiumhydroxide solution, 1M
FOS-03
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