164 / 220
Dual Lab Validation of a Method for the Determination of Fructans in Infant
Formula & Adult Nutritionals /
25 Jul 2016
54
Table 6
Time programming of the detector potential settings of the gold working electrode
Step
Time (sec)
Potential gold
electrode
**)
Integration
detector signal
1
0.00
0.10
2
0.20
0.10
start
3
0.40
0.10
end
4
0.41
‐2.00
5
0.42
‐2.00
6
0.43
0.60
7
0.44
‐0.10
8
0.50
‐0.10
**)
potential vs Ag/AgCl reference electrode
Integration window 0.20 – 0.40 s
A‐11 calibration and calculations
For each analyte (glucose and fructose) use the instrument software to plot a five point standard curve
of (instrument response for the analyte/instrument response for the internal standard chitobiose)
against the concentration of the analyte. Fit a quadratic curve to the data without forcing through zero
(y = ax
2
+ bx + c). Apply the peak area as instrumental response.
The analyses are done with bracketed calibration standards. First the five secondary calibration
standards (S1 –S5) are analyzed. Then 12 samples are analyzed followed by the five secondary
calibration samples.
Thus alternately be analyzed 5 standards and 12 samples. The calibration curve is
calculated using both the 5 standards before the series of 12 samples and the 5 standards measured
after the series with 12 samples.
Use the calibration curve to calculate the glucose and fructose content in the injected samples.
The total fructan content in the analyzed ample is calculated by the following formula:
In which:
C
fructan
= concentration fructan in sample (%m/m)
C
glucose
= concentation glucose in sample (%m/m)set free by the fructanase
C
fructose
= concentration fructose in sample (%m/m) set free by the fructanase
0.91 = anhydro‐factor for oligomers based on an average chain length of 10 monomers
For reconstituted samples the fructan content in the original non‐reconstituted sample can be
calculated from the established fructan content in the reconstituted sample by multiplying with the
reconstitution factor:
)91.0
(
cos
tan
fructose
e
glu
fruc
C
C C
F
C
C
rs
fruc
os
fruc
tan,
tan,
VALIDATION REPORT
FOR ERP USE ONLY
DO NOT DISTRIBUTE