Characteristics and Source Profiles of Volatile Organic Compounds (VOCs) by Several Business Types in an Industrial Complex Using a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS)

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

The topic investigated by the authors is comprehensive and makes a valuable contribution to the field. The introduction + objectives are well-written and provides sufficient background information for the study. It looks like there are a few different font colours in the manuscript, which was a bit distracting (possibly due to the acceptance of track changes by various authors). Authors should have checked the article thoroughly before submission. The article needs several minor edits as follows. 

L21- ‘so on’: please be specific.

L29- ‘suggest t that’: Remove ‘t’

L39-40 : Not all VOCs are pollutants. Reword the sentence.

L74 and L115 ‘so on’: again be specific. Check throughout the manuscript

L82-83- (Korea): Remove ‘Korea’ within the brackets

L131 ‘in recent in these days’: reword

Table 1 caption: Include an explanation for CI-VOC, N-VOC and S-VOC abbreviations, both in the table caption and in-text where it is mentioned first. Helpful for readers.

L-169 ‘for comparative analysis of their characteristics’: Repetition- remove

L183-184 ‘based on the 2021 data 183 from CAPSS’: Repetition- remove

L191-192 ‘One of the major contributors among various industrial sources using organic solvents is the petrochemical industry’:  Include a reference

L224 : Include a reference

L 234 ‘OVOCs and aromatic groups’: Oxygenated VOCs can also be aromatic. Reword the sentence. 

Figure 3 and 4: Replace with a high-resolution images. Hard to read the numbers and legends.

L289: Specific ketones?? Be consistent

L331: m/p-xylene : Italicise ‘m/p-’

L359 : Remove ‘including’

L 417: Remove ‘and so on’

Author Response

Dear Reviewer,

Thank you for your insightful comments and valuable suggestions on our manuscript. We have carefully addressed each of your concerns and made the necessary revisions to improve the quality of the paper. Below, we provide a detailed point-by-point response to each comment.

L21 - ‘so on’: please be specific.

• Response: We have specified the number of industries investigated in this study to be more precise in the expression.

L29 - ‘suggest t that’: Remove ‘t’.

• Response: The typographical error has been corrected by removing the unnecessary 't'.

L39-40: Not all VOCs are pollutants. Reword the sentence.

• Response: The sentence has been revised to indicate that only some VOCs are considered pollutants.

L74 and L115 - ‘so on’: again, be specific. Check throughout the manuscript.

• Response: We have replaced vague expressions like "and so on" with "etc." where appropriate and removed unnecessary instances of vague listings.

L82-83 - (Korea): Remove ‘Korea’ within the brackets.

• Response: While “Korea” was used to clarify an abbreviation, we agree that it is unnecessary and have removed it.

L131 - ‘in recent in these days’: reword.

• Response: We have deleted the phrase ‘in recent’ to correct the sentence structure.

Table 1 caption: Include an explanation for CI-VOC, N-VOC, and S-VOC abbreviations, both in the table caption and in-text where it is mentioned first. Helpful for readers.

• Response: We have added explanations for Cl-VOCs, N-VOCs, and S-VOCs in the caption of Table 1 and provided the definitions where they are first mentioned in the manuscript for reader clarity.

L169 - ‘for comparative analysis of their characteristics’: Repetition- remove.

• Response: The repeated phrase has been removed from the manuscript.

L183-184 - ‘based on the 2021 data 183 from CAPSS’: Repetition- remove.

• Response: The repetitive phrase has been deleted as requested.

L191-192 - Include a reference.

• Response: A reference has been added to support the statement regarding the petrochemical industry.

L224 - Include a reference.

• Response: We decided to delete the sentence as it seemed out of context and unnecessary in this section.

L234 - ‘OVOCs and aromatic groups’: Oxygenated VOCs can also be aromatic. Reword the sentence.

• Response: While we acknowledge that oxygenated VOCs can indeed be aromatic, we would like to clarify that in this study, the VOC species have been defined as distinct groups (as shown in Table 2), and the text was written under this premise.

Figure 3 and 4: Replace with high-resolution images. Hard to read the numbers and legends.

• Response: We have replaced Figures 3 and 4 with high-resolution images to ensure the numbers and legends are clearly readable.

L289 - Specific ketones?? Be consistent.

• Response: We have specified that MEK (Methyl Ethyl Ketone) was used as an organic solvent in the relevant industry.

L331 - m/p-xylene: Italicize ‘m/p-’.

• Response: The notation "m/p-" has been italicized as requested.

L359 - Remove ‘including’.

• Response: The term "including" has been removed as it was unnecessary in the context.

L417 - Remove ‘and so on’.

• Response: The vague expression "and so on" has been removed from the manuscript.

We believe these revisions have significantly improved the clarity and accuracy of the manuscript. Thank you once again for your thorough review and constructive feedback.

Best regards,
Authors.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

The manuscript submitted for consideration is well written. The research is well-reasoned and presented in a logical and affordable manner. The results obtained are interesting. The comments I have on the manuscript are more of an editorial nature. The abstract is treated as an independent part of the manuscript, often only the abstract is immediately available in the databases. Therefore, abbreviations that appear in the abstract if not generally understood must be explained. Most abbreviations used in the abstract have their explanation in Table 3. However, for the reason I described above, they must also be explained in the abstract. In addition, abbreviations are explained the first time they are used. The abstract begins with the abbreviation “VOCs,” which is only explained in the second sentence. The classes of organic compounds listed in l. 114 “...aldehyde, acetate, carboxylic acid, ketone, ester, ether...”. in my opinion should be in the plural. References to ToF version 4.0 (l. 119), Viewer version 3.3.17 (l. 119 and 120) and AME software (l. 137 and 138) should be added. I believe that in Table 1 the CAS numbers are redundant, besides I would use “m/z” instead of “Protonated Mass”. In addition, in Table 1, the groups of compounds should be plural, that is, for example, instead of “alkane,” it should be “alkanes.” Regarding Table 2. The correct notation for the unit of time (second) is “s” and not “sec”. In Equation 1, there should be dots instead of crosses to indicate multiplication. The cross symbol is reserved for vector multiplication, not for scalar values. References to the numerical values given in l. 187 “330,445 tons/yr” and l. 190 “167,568 tons/yr” are missing. In addition, the plural is avoided in the notation of units, so I would suggest the unit “ton/yr”. In the results and discussion section, many values are given in percentages. These are indicative values. In my opinion, it would be better to round them to whole numbers. The captions in Figure 4 are unreadable. It should be corrected. In the Supporting Materials in Table S1, all values should be given with equal accuracy. Meanwhile, some values are rounded to whole numbers. I believe that all values should be given to one decimal place. 

Author Response

Dear Reviewer,

Thank you for your thorough and constructive comments on our manuscript. We have carefully addressed each of your points and made the corresponding revisions. Below, we provide a point-by-point response to your comments.

1. The abstract is treated as an independent part of the manuscript, and often only the abstract is immediately available in databases. Therefore, abbreviations in the abstract, if not generally understood, must be explained. Most abbreviations are explained in Table 3; however, they should also be explained in the abstract. In addition, abbreviations should be explained the first time they are used. The abstract begins with the abbreviation "VOCs," which is only explained in the second sentence.

• Response: We have added explanations for all abbreviations throughout the abstract, including revising the second sentence to ensure the term “VOCs” is explained the first time it is used.

2. The classes of organic compounds listed in l. 114 “...aldehyde, acetate, carboxylic acid, ketone, ester, ether...” should be in the plural.

• Response: We have revised the names of these classes to their plural forms for consistency.

3. References to ToF version 4.0 (l. 119), Viewer version 3.3.17 (l. 119 and 120), and AME software (l. 137 and 138) should be added.

• Response: We have added references to previous studies that utilized these software versions, ensuring proper citation.

4. In Table 1, the CAS numbers appear redundant, and I would suggest using “m/z” instead of “Protonated Mass.”

• Response: We have removed the redundant CAS numbers and revised "Protonated Mass" to "m/z" as suggested.

5. In Table 1, the groups of compounds should be in the plural form, for example, “alkanes” instead of “alkane.”

• Response: The names of compound groups in Table 1 have been revised to their plural forms, such as “alkanes,” for consistency.

6. Regarding Table 2, the correct notation for the unit of time (second) is “s” and not “sec.”

• Response: We have corrected the time unit notation to "s" as suggested.

7. In Equation 1, there should be dots instead of crosses to indicate multiplication. The cross symbol is reserved for vector multiplication, not scalar values.

• Response: We have replaced the multiplication crosses with dot symbols to indicate scalar multiplication, in line with standard notation.

8. References to the numerical values given in l. 187 “330,445 tons/yr” and l. 190 “167,568 tons/yr” are missing. In addition, the plural is avoided in the notation of units, so I would suggest the unit “ton/yr.” Also, many values in the results and discussion section are given in percentages. It would be better to round them to whole numbers.

• Response: The figures 330,445 ton/yr and 167,568 ton/yr are based on the data presented in Table 3, and we have now added a reference to the source in the Table 3 caption. Additionally, we have changed all plural unit notations to "ton/yr" and rounded percentages in the results and discussion section to whole numbers for clarity.

9. The captions in Figure 4 are unreadable. It should be corrected.

• Response: We have replaced the captions in Figure 4 with more readable text to ensure clarity.

10. In the Supporting Materials in Table S1, all values should be given with equal accuracy. Some values are rounded to whole numbers, but I believe all values should be given to one decimal place.

• Response: We have revised Table S1 so that all values are now presented to one decimal place for consistency.

We believe these revisions address all your comments and suggestions and have improved the clarity and precision of the manuscript. We appreciate your feedback and thank you for helping to enhance the quality of this work.

Best regards,

Authors.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript titled "Characteristics and Source Profiles of Volatile Organic Compounds (VOCs) by Various Business Types in Industrial Complexes Using Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS)" presents a quantitative analysis of VOC species across 99 facilities within a South Korean industrial complex. The extensive analysis conducted is commendable and has the potential to significantly advance our understanding of VOC emissions across different industrial processes. However, several aspects of the measurement and analysis methods require further clarification and justification. Therefore, I recommend the manuscript be revised to address the following points:

1. Accuracy of VOC Quantification: The study utilizes the ion transmission rate method for quantifying VOCs. Please provide the transmission rates for each VOC and discuss potential sources of error associated with this method.
2. Detection of Alkanes: The manuscript notes the use of H3O+, NO+, and O2+ for ionization but reports detection of only two alkanes. Please clarify why more alkanes were not detected despite the use of multiple ionization sources.
3. Isomer Separation: The PTR-ToF-MS may face challenges in distinguishing isomers if only molecular ions are used. Describe how the separation between xylene and ethylbenzene was achieved, and provide details on the instrument's resolution.
4. Verification with TO-14A Standard: Explain how the TO-14A standard was used to verify the operation of the equipment.

Reviewer 2 Report

Comments and Suggestions for Authors

Authors identified different VOC profiles in industrial complexes in Korea by use of PTR-TOF-MS instrument. Unfortunately, authors methodology of measurement is absolutely incorrect and leads to false results. They used polyethylene bags, which is known to not be correct material for VOC sampling. Then they used three different primary ions to operate PTR, however they do not report how did they quantified the VOCs from spectra. Moreover, how concentrations were calculated is not clear too: the Ionicon´s software only allows to use k-rate theory to calculate concentrations. I do not know if they used this, as it is completely not reported. However, obtaining concentration only based on this is not accurate. The only accurate way is to do calibration, calculate transmission curve and then calculate all the concentrations of all the VOCs based on this. However why they measured with 3 primary ions? That would produce three different spectra and it would be very hard to get proper concentrations. Such a paper that would put together VOC data from three different primary ions from PTR does not even exist for such a large number of VOCs present here. And here the data processing is not mentioned! In addition, the paper is written in poor and vague English with incorrect chemical naming – for example: substance – that is a mixture, but you mean compound there, etc.

 

line 26: 5,934 mg/day - this means in the whole Korea (South and North?), or single company?

line 35: use proper chemical naming. carbon-based chemicals is not correct. You should write: hydrocarbons

line 46: why you repeat here the same as in line 40?

line 67: incorrect. It is not true, that quantification is weaker for lower m/z compounds. The sensitivity is lower, however it not the challenge for quantification.

line 69: which uncertainties? be specific

line 70: what are low-molecular? Write here the range.

line 73: incorrect, compounds do fragment in PTR. You should rather write: due to its soft ionisation

line 74: be specific. What does it mean specifically: more comprehensive data

line 74: PTR does not provide concentration. It only measures cps or ncps. Concentrations could be estimated by the software, however PTR does not measure that

line 76: PTR does not enable identification and quantification. That is actually the disadvantage of PTR. Software can estimate that, but not PTR

lie 79: "more suitable" - be specific - why?

line 87: you should write here the method for emission calculation. PTr does measure only "concentrations" - after post-processing

line 102: In Introduction you stated that PTR´s advantage is due to its online monitoring. And here you sampled the air not online, but to polyester bag. Moreover, polyester is not proper for VOC measurements. You should use some bags designed for VOCs, such as tedlar, PFA, PTFE etc. So it has been incorrectly sampled.

line 125: how did you moved air sample from polyethylene bags to tedlar bags?

line 127: what does it means significant intensity? Three sigma above zero? Be specific. Functional groups are not in the Table

line 128: do not define OVOC again

line 129: not true. It includes much more..ethers etc

line 131-132: incorrect. It does not mean that they need to be necessarily oxidized again

line 136-137: is that true for all the primary ions?

line 138: incorrect. Not transmission rates, but k-rates

lines 139-143: does not make sense. You had difficulties (why do you write it here?) so that you did not use the calgas and then you write that you use it

line 141: proper operation is checked by the software, not by calgas

table 1: incorrect groups, formaldehyde is not alcohol etc. In addition, you should report here not molecular weight, but m/z which you attribute to the compounds for all three modes (primary ions) in the PTR

2.2: not clear how you calculated concentrations. Where did you take k-rates? In the software they are given as 2 incorrectly and you need to change them. from where di you take them? How did you cope with all three modes? The k-rates are specific for the type of chemical ionization.

Eq 1: add reference to the equation and that in discussion too. Add units to Cj

 

Comments on the Quality of English Language

Bad phrasing, vague wording. Sentences that bears no information.