AOACSPIFANMethods-2017Awards

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1580  H aselberger & J acobs : J ournal of AOAC I nternational V ol . 99, N o . 6, 2016 H ase berger & Jacobs: J urnal of AOAC I nternational V ol. 99, N o . 6, 2016 5

(2) Presence of either GF 3 peaks after ~36 min .—CF = 1.068. (3) Absence of GF 3 and GF 4

and/or GF 4

, along with fructan

Table 2016.06F. PAD waveform Time, s

Potential, V

Integration

and presence of fructan peaks

0.00 0.20 0.40 0.41 0.60 0.61 1.00

+0.05 +0.05 +0.05 +0.75 +0.75 –0.15 –0.15

after ~36 min .—CF = 0.9526. Discrete ingredient commodity examples are shown in Figures 2016.06A–C . Oligofructose containing materials derived from the partial hydrolysis of chicory inulin often display a characteristic peak with significant tailing at ~5 min, as illustrated in Figure 2016.06B . If identification of fructan type is difficult, it may be helpful to also inject a selection of different commodities for direct comparison.

Begin

End

Part II – Quantitative Determination of Total Fructan

proven adequate for the qualitative determination required here, including for matrices containing maltodextrins (which tend to be the most problematic, in particular with respect to determining presence of GF 3 and/or GF 4 ). If necessary, it is acceptable to modify the Part I separation conditions to optimize resolution. (b) Electrochemical detector parameters.— This method utilizes the carbohydrate triple waveform per Table 2016.06F . Note : This waveform is not appropriate for disposable gold electrodes. The reference electrode is set to AgCl mode. (c) Injection.— Make a single 4 µL injection of each sample test solution. At the start of each sequence, make six equilibration injections (one may use laboratory water or extra standards for the equilibration injections) to ensure that system is stable, followed by the two retention time standards. Bracket samples with standards after every six injections. Maintain autosampler sample compartment at 10°C. G. Data Interpretation and Assignment of Commodity Factors (CF) Using chromatograms from analysis of the RT standards for reference, determine whether GF 3 , GF 4 , and higher DP fructan forms (evidenced by peaks after ~36 min) are present in the test sample(s). Assign commodity factors based on the following rules: (1) Presence of either GF 3 and/or GF 4 , but no fructan peaks after ~36 min .—CF = 1.233.

H. Apparatus and Materials (a) LC system.— One biocompatible gradient pump; biocompatible refrigerated autosampler capable of injecting 4 μL; electrochemical detector with gold electrode capable of pulsed amperometric detection. For example, Dionex ICS-3000 or 5000 consisting of an SP, DP, WPS-3000 (TB; P or S type), and an electrochemical cell with a conventional gold working electrode and combination pH Ag/AgCl reference electrode or equivalent. (b) Analytical column set . — Analytical column, Thermo CarboPac PA1, 250 × 4 mm; borate trap (replaces guard

column), Thermo Part No. 047078 or equivalent. (c) Analytical balance.— Readable to 0.01 mg. (d) pH meter.— Readable to ±0.01. (e) Water bath, 40°C.— Maintained at 40 ± 2°C. (f) Syringe filter.— 0.45 µm nylon.

(g) Volumetric flasks.— Glass, Class A, assorted sizes. (h) Volumetric pipets. —Glass, Class A, assorted sizes. (i) Centrifuge tube.— 5 mL plastic (or greater, extra volume

allows for room to neutralize excess reagent). (j) Microcentrifuge tubes.— Assorted sizes. (k) Polypropylene beaker.— 100 mL. (l) Screw capped vials.— No metal lined caps. (m) Graduated cylinders.— Glass, assorted sizes.

FOS

ED_1

125 111815-fructanqual ID #7

nC

1 - 2.250

110

2 -GF3 - 2.650

100

90

80

70

60

50

40

30

3 -GF4 - 3.350 4 - 3.600

20

10

6 - 4.867

8 - 42.500

5 - 4.517

7 - 6.417

min

-5

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

34.0

36.0

38.0

40.0

42.0

44.0

46.0

48.0

50.0

52.0

54.0

56.0

58.0

60.0

Figure 2016.06A. scFOS chromatogram (Part I).