154 / 620
Page
2
of
14
Sample Preparation
1.
Powder sample reconstitution (if needed) –
Accurately weight 5.0 g ± 10% into a 100 mL beaker (record
powder weight)
. Tare
and deliver 40 g of lab water to beaker (record
water weight
). Allow to stir for 30 minutes, or until dissolved.
2.
Sample dilution –
Samples require differing dilutions according to their individual fructan content as follows. Record all weights
to four decimal places. This aliquot can be shared with the quantitative fructan methodology in Part 2.
Table 1-1
Sample Size Guidelines
Sample type
Fructan Level
(as-is)
SW
1
(g)
Volumetric Flask Size
(mL)
Powder Product
0.27-1.0%
10 g± 10%
50
Powder Product
1.1-10%
7 g± 10%
200
Powder Product
11-45%
4 g± 10%
500
RTF Product
*
0.03-0.20%
10 g± 10%
50
RTF Product
*
0.21-1.0%
7 g± 10%
200
RTF Product
*
1.1-5.0%
4 g± 10%
500
Commodity
45-100%
0.4 g± 10%
1000
*
For concentrated liquid (CL) products dilute 10 mL of product with 10 mL of laboratory water and then treat the resultant material
per RTF guidelines.
3.
Filtration and analysis –
After bringing the samples to volume, filter through a 0.45 µm nylon syringe filter into an autosampler
vial (prepared samples can be stored in vials at 2-10
°C for 5 days)
.
Instrument Conditions
1.
Gradient –
Fructans are eluted using a gradient of NaOH and sodium acetate at 1.0 mL/min as per figure 1-1 below. Column and
detector compartment are maintained at 20
°
C.
a.
Please note that a Carbopac PA1 guard is used for this procedure rather than the borate trap used in part 2 for
quantitative fructan determination.
2.
Injection –
A single 4 µL injection of each sample test solution is made. At the start of each sequence, 6 precision injections are
made to ensure that system is stable, followed by the 3 retention time standards. Samples are bracketed with standards after
every 6 injections. Autosampler is maintained at 10
°
C.
3.
Electrochemical detector parameters –
This method utilizes the carbohydrate triple waveform referred to in Thermo/Dionex
Tech Note 21, Waveform B (4).
Note this waveform is not appropriate for disposable gold electrodes!
The reference electrode
is set to AgCl mode.
Figure 1-1
Qualitative ID Gradient
FOS-04
FOR ERP USE ONLY
DO NOT DISTRIBUTE