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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, but would like to see a sample blank for comparison
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
5. Based on the supporting
information, what are the
pros/strengths of the
method?
1. specificity for Theanine
2. meets SMPR requirements for Theanine (LOQ, analytical range)
6. Based on the supporting
information, what are the
cons/weaknesses of the
method?
1. Single source (Pickering Labs) of mobile phase (Li-citrate buffer), cation-exchange
column, and post-column derivatization reagent
2. Post-column derivatization system - only one from Pickering demonstrated; not sure
what other options are out there for use and if they would be similar enough to
generate equivalent results
3. analysis time (ca. 62 minutes injection to injection)
4. did not see sample blank injections; in particular interested to see if any co-elution
with ISTD (L-norleucine) in some of the samples where there appear to be other small
peaks eluting nearby
5. method applicable to Theanine only; other analytes of interest in Tea will require a
separate method (but don't see how this can be avoided)
6. identification of potential interferences from various sample matrices eluting near
ISTD (e.g. in green tea softgels)?
7. Any general comments
about the method?
post-column derivatization does add some complexity and potentially impact detection
limits; however, method results appear to suggest this is not a limitation here
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.
Yes
Need multiple lab date to demonstrate how this method performs in unaffiliated lab
environment in order to demonstrate ease of use, reproducibility, and applicability on
different post column derivatization systems