Thanks for your revisions to the original manuscript that have largely satisfied the reviewers' concerns. Please address the remaining minor issues they highlight (combined below). I support Referee #2's suggestion to describe the method as "semi-quantitative" (but very promising) at this point. In addition, please carefully go through the references and ensure that the formatting matches Copernicus requirements. For example, sometimes journals are fully spelled out rather than abbreviated, sometimes article titles are capitalized and sometimes not, etc. (see Bianchi et al., Donahue et al., Brueggemann et al., 2015 for examples). This is an unfortunate consequence of EndNote-type software--it never gets the formatting quite right.

Referee #1:

As a proof-of-concept paper and introduction of a new technique, I recommend publishing the paper after the authors address the concerns presented below.

Page 4, line 134: I think the wrong figure maybe referenced.
Page 5, line 183: "according to the reaction equation the same as the concentration" is unclear what the authors mean
Page 6, line 192: "As mentioned above also TPP particles" is unclear what the authors mean
Page 6, line 197: if the error is only shown to the tenth unit (0.1) then the background contribution should be similar (1.2)
Page 6, line 201 (Eq. 10): It's unclear what the 0.012125 came from or what it represents
Page 6, line 211 - 212: Please mention that you will explain later why TPP rose quickly once ozone was introduced. Without saying you explain why, it is a shock.
Page 7, line 265: It should be "since TPP also moves"
Figure 6: Since you are comparing the different mass distributions, it would be use to at least mark where the maxima was from the prior panel. Since it is in log scale, it's hard to mentally line up the changes in diameter that is described in the text.
Supplement: I appreciate the authors using Kuwata et al. to estimate the SOA density; however, I do not recall the authors referencing they did this in the main paper. Instead, the only reference for density is on page 7, line 233, where they state a value that is sometimes assumed as it was measured in other studies. Please reference the supplement.

Referee #2:

- “to detect” rather than “to detected” (line 12).
- I would prefer that the technique demonstrated be described as “semi-quantitative” rather than “quantitative” (line 18).