Direct Mass Spectrometry with Online Headspace Sample Pretreatment for Continuous Water Quality Monitoring
Round 1
Reviewer 1 Report
I read the paper and I think that it is a good work.
I only suggest to improve the state of the art (adding references), for example I suggest to add this paper:
- Panepinto D., Genon G. (2010), Modeling of Po River Water Quality in Torino (Italy), Water Resour Manage (2010) 24:2937–2958, DOI 10.1007/s11269-010-9588-x
Good luck!
Author Response
Dear Reviewer I,
I appreciate your wonderful comments and suggestions.
As you mentioned in the revision, authors were considered to add “Modeling of Po River Water Quality in Torino (Italy)” in the manuscript. We agree with your opinion, but for further modeling studies to take place, the basic data (e.g., site-specific flow-rate, pollution loading, chemical transport based on advection, etc.) in the Nak-dong River is limited.
As following your comment, We considered two state-of-art references [35-36]. These references are related to water treatment processing efficiency and treatment capacity [35], and chemical toxicity [36].
Thank you for your nice suggestion again.
Reviewer 2 Report
this is an interesting manuscript however it needs some improvement
1) the abstract is not very understandable for the average reader. you state
The reaction rates of the target compounds introduced using the headspace method were
similar to those of the mass scan library with a margin of error < 10%. and then you state However, the variability in individual
concentrations was still large due to the unstable control of sample injection flow and pressure. Herein, 79% of
the 28 compounds met one-tenth of the proposed method detection limit criteria for emergency operations in
WWTP.
what you mean by unstable control? what are these detection limits according to whom? also finally if the individual compounds detection limit is not very good how can this method be used for accident detection?
please elaborate on all these mentioned here
2) in the 1st paragraph I dont understand what is claimed. you say that there are limits for the discharge of specific harmful substances from chemical waste water
facilities, but there are no limits for the discharge of chemicals from
waste water treatment plants (WWTPs)? this is the same thing I believe
3) you state In some cases, measures should also be taken to sequester the inflow into
emergency storage facilities. I do not undestand what that is
4) please use the passive voice instead of active (eg we chose) whenever posible
5) I understand certain contaminants designated by the Ministry of Environment of Korea but why you tested hazardous air pollutants
designated by the United States Environmental Protection Agency? these are air pollutants why they can be found in water?
6) replace from o2si smart solutions, an LGC Standards Company (Charleston, SC, USA)
with
from o2si smart solutions (Charleston, SC, USA)
7) you state Selected standards as stock solutions in triacetin were
purchased from o2si smart solutions, an LGC Standards Company (Charleston, SC, USA) in three different groups,
considering the reactivity between the individual chemicals.
I do not understand this. you mean groups that contained combinations of these chemicals? what did these groups consist of? didnt you have to test for LOQ LOD for the individual chemicals beforehand? it is a bit confusing here
8) replace
We confirmed that the matrix did not include the interference m/z of the target substances in the
SIFT-MS.
with
It was confirmed that the matrix m/z did not intervene with these of the target substances
9) you state This solution was used for validating the
m/z to compare the library of compounds from the gas phase with those of vaporized compounds from the liquid
phase I do not understand this sentence. generally this part of materials and methods is very confusing regarding the SEQUENCE of experiments done.were one by one substances diluted and mesured via X in relation to Z? Were mixtures of known concentrations measured? what preceded what?
10) you state The headspace pretreatment system is considered to be the most effective means to extract target chemicals
contained in a liquid [23-26] into a gas phase for transfer to the SIFT-MS (Ref)
obviously a reference is missing here. Furthermore, these comments are fit for introduction or discussion not for materials and methods
11) you state We confirmed the m/z of each substance by comparing them with the
library in mass scan mode
what library is this? give reference
12) you state Then, the optimized method was developed to avoid interference with multi ions and
to ensure correct quantification
what is this optimized method what it consist of?
13) in test sites you state that the WWTP receives both municipal and industrial effluents. why in the introduction you talk only about industrial effluents?
14) as I understand correctly there are no pollutants to be measured in effluents according to the legislation only TP, TN, SS, and COD? how is that possible? not even in special circumstances (eg if industriale effluents are present or if the recipient is a sensitve ecosystem?) please elaborate. you state: After incorporating treatment facility average removal rates, reference contamination levels
following chemical accidents for the shut-off and operation of emergency storage facilities at WWTPs were
proposed (Temporary Criteria of Inflow Blocking of contaminated water, TCIB) I do not really understand this sentenceand what it means. are these supposed to be some criteria applied at least? why you call these criteria preliminary?
15) as I understand the method is good for monitoring because its limit of quantification is higher than the criteria set? is that what it is? because you did not find anything in the effluent besides methanol. on what grounds you claim this method is good for wwtp monitoring?
16) the discussion is good however you should focus more on the qualitative meaning of your findings and leave the bulk of findings in the tables and figures
17) please add the following references
Stasinakis, A.; Gatidou, G.; Mamais, D.; Thomaidis, N.S.; Lekkas, T.D. Occurrence and fate of endocrine disrupters in Greek sewage treatment plants. Water Res. 2008, 42, 1796–1804.
An insight into ingredients of toxicological interest in personal care products and a small-scale sampling survey of the Greek market: Delineating a potential contamination source for water resources. Emmanouil C., Bekyrou M., Psomopoulos C., Kungolos A. (2019) Water (Switzerland), 11 (12) , art. no. 2501
18) In refernces you cite
Ministry of Environment, Water Environment Conservation Law Enforcement Regulations Article 3 & 4; 2017.
2. Korea Environment Coporation. Information System on Prevention of Water Pollution
and
Ministry of Environment. Environmental Testing and Inspection Act; 2017
are these in Korean? it should say so. also it must be Korea Environment Corporation. please double check for this kind of mistakes
19) In table 3 what the asterisk stands for?
20) In Fig 4 why there is a standard error on the bars? were there many repeats? can you do a t-test between the two methods for each substance to check the two methods?
21) in Fig 5 you should rename the bridge1 2 and 3 to the actual name sites? because this name right now does not mean much. also again can you do an ANOVA test between the 3 sites to test for differences?
22) I think it is possible to omit some tables and figures eg Fig 3 and Fig 2 can be incorporated in Fig 1
Author Response
Dear Reviewer II,
We thank for your comments for highlighted errors in the logical description of the paper submitted. For your comments, we have revised the text in the paper. Our response to your comments are summarized below. The modified main parts are marked in red.
Thank you for your consideration.
Author Response File: 
Author Response.doc
Reviewer 3 Report
Please find the attached review comments.
Comments for author File: Comments.docx
Author Response
Dear Reviewer III,
I appreciate your wonderful comments and suggestions.
I was able to confirm that my article improved because of your comment.
Thank you for you nice suggestion again.
Round 2
Reviewer 2 Report
in introduction you state
composition of different chemical species in water samples for
the prevention of chemical spill
actually you do not prevent the spill but you do early detection of the spill
In table 1 why in ethylene oxide there are 2 values for solubility?
Fig 1 is assumed that it is created by you, correct?
Fig 2 is a bit small to be readable. please pay attention for the printed form
you state
Based on the t-test, p-values for eight compounds (acrylonitrile, nitromethane, butanone, methyl acrylate,
301 naphthalene, 1,4-dioxane, tetrachloroethylene, and bromoform) were less than 0.05, and headspace-SIFT-MS and
302 conventional headspace-GC-MS were not significantly different for these compounds
I am not sure, have you stated in materials and methods that you will perform a t-test? if not this phrase should be rewritten such as... an independent samples t-test was performed for the results obtained by ... and the results obtained by... in the cases ... p value was MORE THAN 0.05 as such no statistical difference was noted for these substances
I still believe that there are too many graphs and figures. maybe some least significant can be added in a supplementary file?
Author Response
I agree with you. We revised it as follows.
Point 1: in introduction you state
composition of different chemical species in water samples for
the prevention of chemical spill
actually you do not prevent the spill but you do early detection of the spill
Response 1: Yes, you're correct. The purpose of applying this method is early detection.
(L 81 in dark red)
Point 2: In table 1 why in ethylene oxide there are 2 values for solubility?
Response 2: solubility estimates of ethylene oxide was deleted. (Table 1 in dark red. Later, this was reorganized into supplementary information)
Point 3: Fig 1 is assumed that it is created by you, correct?
Response 3: Yes. Fig. 1 was drawn by ourselves and the conceptual system was also designed by ourselves.
Point 4: Fig 2 is a bit small to be readable. please pay attention for the printed form
Response 4: As your point, Fig 2 is rearranged up and down to increase readability.
It was also repositioned as supplementary information. (SI 번호 in dark red. Later, this was reorganized into supplementary information.)
Point 5: you state
Based on the t-test, p-values for eight compounds (acrylonitrile, nitromethane, butanone, methyl acrylate,
301 naphthalene, 1,4-dioxane, tetrachloroethylene, and bromoform) were less than 0.05, and headspace-SIFT-MS and
302 conventional headspace-GC-MS were not significantly different for these compounds
I am not sure, have you stated in materials and methods that you will perform a t-test? if not this phrase should be rewritten such as... an independent samples t-test was performed for the results obtained by ... and the results obtained by... in the cases ... p value was MORE THAN 0.05 as such no statistical difference was noted for these substances
Response 5: We added the sentence in “Materials and Method” part, Line 182-184.
To compare the two different analytical methods, the response of twenty-one compounds, which could be analyzed traditional headspace-GC-MS, was verified by comparing them with t-test by using Microsoft Excel 2016 for Windows.
Point 6: I still believe that there are too many graphs and figures. maybe some least significant can be added in a supplementary file?
Response 6: Reflecting your opinion, we have reorganized fig 2, table 1 and table 3 into supplementary information. Accordingly, the figures and table numbers of all texts have been modified.
Thank you.
Author Response File: Author Response.docx
