Dear Authors,

Thanks for revising the manuscript and providing detailed responses to comments made by two reviewers, who are the experts on the area. I read carefully the original ms and the revised one as well based on the comments and with my own eyes.

The two reviewers provided substantial comments.
The most important comments include below.
- There are other potential sources of 14C contamination along with laurylamiine which is the main target in the present manuscript. Acetic acid is made from organic and inorganic sources as well. Another candidate of 14C contaminant is Eucalyptus oil, whose constituent is organic compounds.
- Test on the removal of lauylamine by stepwise pre-heating from 200 to 500 dC.
- Bedrock sample may have some unknown amount of carbon. The authors had better use CRONUS-A despite it is already clean quartz because its 14C concentration is known and confirmed.
- Different procedures for extracting in-situ 14C among a handful of labs. Is there any possibility that some high level of modern carbon can be due to blank magnitude and variability rather than leftover laurylamine?

I found most of major issues are well explained, making substantial modification of the original manuscript. I know one major one about “acetic acid” is not confirmed by the authors. However, I believe that the present manuscript makes great contribution to the new technology of in-situ 14C dating which is still under infancy. The unresolved matter such as acetic acid as another potential source 14C contamination during frothing process should/would be dealt with by the following researches.

Other minor comments are also well explained, along with proper modification.

Thanks again for submitting your interesting findings.

Associate Editor,
Yeong Bae Seong.

Please submit the revised version as described in your responses to the review comments. Thanks --