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2. Does the method contain
system suitability tests or
controls as specified by the
SMPR? If not, please indicate
if there is a need for such
tests or controls and which
ones.
Yes. A blank check sample could be added to comply with SMPR.
Consider modifying the statements about retention times to include an acceptable %
deviation with a specified number of replicate injections.
3. Is there information
demonstrating that the
method system suitability
tests and controls as
specified in the SMPR worked
appropriately and as
expected? If no, please
specify.
Yes.
4. Based on the supporting
information, is the method
written clearly and concisely?
If no, please specify the
needed revisions.
Yes. I would add more guidance under the section for sample preparation to assist in
choice of sample size and extraction volume. Something like "Choose sample size
corresponding to approximately X mg of theanine".
5. Based on the supporting
information, what are the
pros/strengths of the
method?
The method is simple and straightforward (sonication extraction, chromatography,
detection).
The method has demonstrated accuracy via use of reference materials as well as
spike/recovery studies.
The method has demonstrated adequate precision as specified in the SMPR.
The method has adequate linearity, LOQ, and LOD as stated in the SMPR.
6. Based on the supporting
information, what are the
cons/weaknesses of the
method?
High marginal spike/recovery for liquid green tea product (108.7%).
The post-column reactor may be considered "specialized equipment".
Unknown how method would respond to gummies/chewables (2 difficult matrices).
Sonication extraction might not be sufficient.
Ruggedness tests showed sensitivity of the method to the ratio of sample mass to
extraction solution volume and also post-column reactor temperature. Adding a
statement to the sample preparation section can assist with the selection of appropriate
sample size and extraction volume, to reduce likelihood of such issues. In addition, a
statement could be added to the apparatus section regarding calibration of the post-
column reactor temperature.
7. Any general comments
about the method?
Very good method for determination of theanine. While it doesn't meet the full
applicability of the SMPR, it is promising as a method for theanine and could be used
in conjunction with another method for the other analyte classes.
Do you recommend this
method be adopted as a First
Action and published in the
Official Methods of Analysis
of AOAC INTERNATIONAL?
Please specify rationale.
The method is a strong candidate, but without understanding of how the method will
behave with gummies and chewables (2 difficult matrices that were specifically
indicated as important by the working group), I do not recommend that this method is
adopted as first action at this time.
I recommend that the authors conduct additional studies using gummy and chewable
supplements and resubmit, as the method has demonstrated potential.