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Table 2-7
Method comparison
New method 997.08
1
999.03
2
Reference 3
Number of sample
preparations and analyses
needed to complete testing
1
3
3
1
Instrument Run time (min)
45
83x3=249 NAP
65
Can test samples with
sucrose:fructan ratio >3:1
Yes
No
Yes
Yes
Requires post-column
reagent addition
No
No
NAP
Yes
Applicable to FOS,
oligofructose, and inulin
Yes
Yes*
Yes*
Yes
Requires extraction step
No
Yes
Yes
Yes
Requires SPE
No
No
No
Yes
Requires dry-down
No
No
No
Yes
Requires knowledge of
commodity type for
accurate results**
No
Yes
Yes
Yes
Method bias for any
commodities
No
No
Yes
No
Uses borate trap
Yes
No
No
No
LOQ (% on RTF basis)
0.03%
(90.8-115%
recovery)
0.5% 0.5%
0.014%
(83-101%
recovery)
%RSD (Intermediate
Precision)
2.04-7.12% 5.79% 1.25% 4.22-8.37%
1
Stated method performance taken from Covance labs website effective 10/15/2010.
2
Stated method performance taken from Covance labs website effective 01/21/2005.
*Method accuracy compromised by usage of set DP factors of 4 and 10 (actual range
is from 3.7-30).
**Limits utility at a regulatory level where the type of material may be unknown or
testing for off-label adulteration may be desired. The new method circumvents this
via the qualitative ID methodology in Part 1.
Conceptually this methodology is similar to that of Cuany, et. al. (3) However several time savings are gained from the
elimination of extraction, SPE, and sample dry-down. An additional time savings is generated in a shorter instrument cycle
time (45 minutes versus 65 minutes). Some of this is due to the incorporation of a borate trap in place of a standard PA1
guard. Borate negatively impacts HPAEC-PAD chromatography, creating peak distortion and other issues previously
observed (3, 5). Furthermore, the addition of the internal standard (as suggested in 997.08) allows for a non-volumetric
dilution and a subsequent improvement in LOQ.
1.
Linearity
–
For the 43 standard curves examined no calibration errors greater than + 5% were observed (see figure 2-3).
As expected the largest errors were observed in the lowest level standards. However the pattern of errors does not
indicate any systematic trends.
Fos-04 (February 2016)
FOR ERP USE ONLY
DO NOT DISTRIBUTE