This manuscript describes a study on the chemical composition of primary and photooxidation generated-secondary organic species (both gas and particle phases) from a EURO 5 gasoline under Artemis cold urban, hot urban, and motorway cycles. Gas and particle phase chemicals were analyzed by a chemical analysis of aerosol on-line (CHARON) inlet coupled with a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS).  Gas-to-particle partitioning was presented as volatility distributions. I must admit that I am not an expert on organic aerosols. Therefore, I cannot provide expert opinion on the technical quality or novelty of this study. I do have some specific and technical comments as listed below.

Specific comments:

1. Section 2 Experimental. Page 4 Line 110-111: It will be worthwhile to explain the hypotheses for running the cold urban cycles at three different conditions (Experiments 1 to 3) as well as for using different dilution ratios. The result section then needs to explain if these hypotheses were tested true. Other than listing data in the tables or figures, the authors spent little effort to explain the differences from different cycles, either from the source of the differences or their real-world implication perspectives.
2. Table 1: Please describe why the VOC and NOx concentrations for Exp 1-3 are much higher than Exp. 4-5.
3. Page 5 Line 150. What are the sources for such high concentrations of ammonium nitrate? Section 4.3 mentioned that NH4NO3 particles may grew to >600 nm to clog the AMS orifice. It would be good to include size distribution evolution plots in supplemental materials, as the particle lifetime in the chamber as well as transmission efficiencies through inlets would change with particle size. Fig. 4 only shows two instant distributions, not time series.

Technical corrections:

1. Abstract Page 1 Line 24, I would revise the sentence to: “Comparing our results to the theoretical estimations for saturation concentrations, we observed…”
2. Page 2 Line 57: Delete “…the those…”
3. Page 3 Line 67: Change “Except for” to “Besides”
4. Page 3 Line 68: Change “weather” to “whether”
5. Page 5, Line 129: missing a “)”
6. Page 5, Line 133: explain acronym “E/N”
7. 1: should TS include inorganic aerosol?
8. 2: explain the parameter K_p,i
9. Page 14, Line 431: missing a “(“
10. 1-3: the y-axis’s are fractions rather than %.

The authors applied for the first time PTRMS equipped with a CHARON device to the photooxidation products of gasoline vehicle exhaust and measured the molecular distribution of precursor gases, product gases, and product particles. The detected gas and particle products were consistent with the results of previous chemical analyses of aromatic hydrocarbon chamber experiments. The saturation concentrations of selected products were estimated from the gas-to-particle ratios. The average saturation concentration of secondary organic aerosol (SOA) particles was evaluated to be higher for lower organic aerosol concentrations, consistent with the gas/particle partitioning model. The saturation concentrations evaluated by present experiments were compared with theoretical predictions.  A novel aspect of this study is the quantitative evaluation of gas particle distribution at the molecular level with respect to the subject gasoline vehicle SOA. However, the current manuscript does not adequately discuss the uncertainties in the sensitivity ratios of gas and particle analytes that may interfere with the evaluation results. There could be a more in-depth discussion of fragmentation as well. Therefore, this manuscript can be expected to be published but needs to be revised.

(1) Line 24 (abstract). What is "theoretical estimations"? Could you add explanations?

(2) Lines 48-50. Morino et al. (2022) should be added as a recent paper that experimentally discussed photooxidation products in gasoline vehicle exhaust.

Ref. Morino, Y., Li, Y., Fujitani, Y., Sato, K., Inomata, S., Tanabe, K., Jathar, S.H., Kondo, Y., Nakayama, T., Fushimi, A., Takami, A., Kobayashi, S. Secondary organic aerosol formation from gasoline and diesel vehicle exhaust under light and dark conditions, Environ. Sci.: Atmos., 2, 46-64, 2022.

(3) Lines 163-164 and 417-428: Does the statement in lines 163-164 mean that there is a maximum uncertainty of about 100 in the ratio of the CHARON-PTRMS signal to the PTRMS signal? Is it correct that there is an error of ±2 in the logC* measured in this case? If the experimental error is ±2, many experimental results agree with theory within the error range, and discussion described at lines 417-428 might be too much detailed. Other than the cited reference, is there any experimental evidence that would allow a specific discussion regarding the uncertainty of the ratio of the CHARON-PTRMS signal to the PTRMS signal for present measurement subject compounds? 

(4) Lines 311-324. With respect to nitroaromatics, there may be underestimation due to fragmentation compared to aldehydes and ketones. If available, please discuss any experimental information on fragmentation of nitroaromatics. The authors assume that heterogeneous processes are important for the formation of nitroaromatic hydrocarbons, but there is also a hypothesis that nitrophenols are formed by gas-phase reactions of phenoxy-type radicals with NO2 (e.g. Harrison et al., 2005). Is there any evidence from the results of this study to support the hypothesis of heterogeneous reactions?

Ref. Harrison, M.A.J., Barrra, S., Borghesi, D., Voine, D., Arsene, C., Olariu, R.I., Nitrated pheols in the atmosphere: a review, Atmos. Environ., 39, 231-248, 2005.

(5) Lines 382-384. The author discusses the cause of the experimental results, but it is not clear. Do the authors want to write that the experimental results are qualitatively explained by the gas/particle partitioning model?

(6) Line 431. There is an end of parentheses, but the beginning of parentheses is unclear.