AOAC OMB Final Action Recommendation (December 2019)-2016.14

FOS-03 FOR WORKING GROUP/ERP USE ONLY DO NOT DISTRIBUTE

inulinase) to hydrolyse fructans into fructose and glucose and the released fructose is

measured by HPAEC-PAD. The total fructan content of the sample is obtained by comparing

the area of the chromatographic peak of fructose from the sample with that of a fructose

standard solution. The result is corrected by using a correction factor (k) to adapt for water

uptake during fructan hydrolysis. A further correction factor (p) takes into account the loss

of the terminal fructose of reducing Fm type fructans (since it has been converted to sorbitol

or mannitol during the reduction stage) or the glucose from GFn type frucans (since glucose

is not measured during the HPAEC-PAD analysis). These factors (k & p) are easily calculated

from the average DP of the fructan ingredient.

C. Apparatus & Materials

(a) Anion exchange chromatograph (HPAEC) comprising a gradient pump with 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; injection volume 20 μL; post column delivery flow rate 0.6 mL/min.

(c) LC columns – Analytical column, Carbopac PA1 250 x 4 mm, 10 μm particle size ;

Guard column, Carbopac PA1, 50 x 4 mm

(d) Analytical balance with ± 0.1 mg readability.

(e) Centrifuge

(f) Vacuum centrifuge

(g) pH meter

(h) Water bath maintained at 80°C (±1°C).

(i)Water bath maintained at 40°C (±0.2°C).

(j)Vortex mixer

(k) LC injection vials; 1.6 mL, with pre-slit PTFE/silicone septa

(l)Vial inserts; 100 μL, glass pulled point

D. Reagents

(m) Milli-Q purified water, 18 MΩ (all references to “water” refer to this).

(n) Sodium hydroxide solution, 50% (w/w)

(o) Sodium hydroxide pellets, GR for analysis

(p) Sodium hydroxide solution, 1 M