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General comments about the method:
ER 1
In-house validation report was not available to review the method.
ER 2
The method is well established and is known to generate false positives with soy products (e.g.,
soy milk) that the use of milk powder does not eliminate. This is never mentioned but instead
the use of milk powder is presented as a solution~ .The authors should re-write the documents
with a more open / critical perspective. -There is also a serious question of why they did not
use corn flour that was totally free of gluten and prepare cookies with known levels of 0, etc
etc.
ER 3
none.
ER 4
Method is well written and the experimental details and instructions provided to participants
were very clearly laid out. The pre-collaborative tests were organized properly and sufficient
time was given to participants to demonstrate proficiency prior to undertaking to analyze the
collaborative method samples.
ER 5
The method is very sensitive, I wonder that maybe -looking at the action level of 20 mg/kg- the
LFD method could be too sensitive? Another point as with the R5 sandwich, the gluten content
= 2 x gliadin. Unifying results to gluten content will be helpful instead of using mg/kg gliadin
ER 6
The dip stick assay based on R5 antibody is meant for a rapid qualitative visual detection of
gluten in processed and non-processed samples. The scope of the method to detect intact
gluten (prolamins) includes matrices like corn, wheat, rye and barley. The non-processed
samples are extracted in 60% ethanol and processed samples are extracted in a proprietary
cocktail provided in the kit. The assay has been designed to detect gluten well below the
threshold level of 20 mg/Kg. The reproducibility of the assay has been evaluated in corn
sample and processed samples like cookies and corn snacks. The assay provides positive results
above 2.5 mg/kg in non-processed foods and above 4 mg/kg in processed foods. The positive
results are produced if a surface contains more than 1to 2 mcg gliadin/100 cm2. .
ER 7
NA
ER 8
The R5 dipstick has been in the market for a long time. It’s applicability to food matrices are
recognized. However, food surfaces application appears to be an afterthought. No validation
data were presented or reported elsewhere. As mentioned in the manuscript, a positive band
can have non-uniform color intensity due to in-homogenous distribution of gluten on the
dipstick sample pad. This may be a sampling protocol flaw and may give an inconsistent result.
Pros/Strengths of the Manuscript:
ER 1
Well designed study with appropriate controls. study includes validation of methods for both
processed and non-processed foods
ER 2
none that was obvious. Other dipsticks have been more rigorously validated with inclusion of
cross-reactivity (inclusivity / exclusivity agents). and use of surface testing.
ER 3
I think the method looks pretty good. Some issues with the manuscript
ER 4
The authors clearly identify gliadin as what is being measured by the test kit and this is made
ERP PROFILE SUMMARIES
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