Simultaneous Determination of 17 Phenolic Compounds in Surface Water and Wastewater Matrices Using an HPLC-DAD Method

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript environments-2901273 presents the simultaneous determination of 17 phenolic compounds in surface water and wastewater matrices using a HPLC-DAD method.

The text is well-written. Some minor comments are included below:

 

1. L.15: phenols
2. L.59: Please, define “HG”.
3. Ls.115-6: not clear.
4. L. 125: Extra information about “Dinoseb” is needed, e.g., chemical formula etc..
5. Table 1: Extra information about “Log Kow” is needed.
6. Ls. 186-96: Add References.
7. L.225: “maxima”.
8. Ls. 487-8: Explain why.
9. L. 532: “analyze”.
10. L. 638: “analyze”.

 

Comments on the Quality of English Language

Minor editing of English language required

Author Response

I would like to express my sincere gratitude for your thorough review and evaluation of our manuscript. Your insightful suggestions and observations have greatly contributed to the improvement of our work. We truly value the time and effort you have dedicated to providing us with valuable feedback. Your expertise and attention to detail have been instrumental in enhancing the quality of our research. We are committed to addressing the points raised in your review and incorporating your suggestions to further enhance the clarity and impact of our manuscript. Once again, thank you for your invaluable contribution to our work. Please find below all the answer of your suggestion:

Q1. L.15: phenols

A1. Modified accordingly

 

Q2. L.59: Please, define “HG”.

A2. Modified accordingly

 

Q3. Ls.115-6: not clear.

A3. The phrase has been modified to be more clearly

 

Q4. L. 125: Extra information about “Dinoseb” is needed, e.g., chemical formula etc..

A4. Dinoseb is a common industry name for 6-sec-butyl-2,4-dinitrophenol, a herbicide in the dinitrophenol family. The name was also added in the Chemicals and materials section

 

Q5. Table 1: Extra information about “Log Kow” is needed.

A5. Supplementary information has been added in the Chemicals and materials section: ‘Log Kow represent the octanol-water partition coefficient and pKa is a number that describes the acidity of a particular molecule’

 

Q6. L. 186-96: Add References.

A6. A reference has been added

 

Q7. L.225: “maxima”.

A7. Modified accordingly

 

Q8. L. 487-8: Explain why.

A8: The following explanation has been added: ‘This helps determine the method's reliability in accurately quantifying the true con-centration of phenolic compounds. If the recovery experiment shows good agreement between the measured and expected concentrations, it indicates that the method is reliable and trustworthy in determining the true levels of phenolic compounds in the samples.’

 

Q9. L. 532: “analyze”.

A9. Modified accordingly

 

Q10. L. 638: “analyze”.

A10. Modified accordingly

Reviewer 2 Report

Comments and Suggestions for Authors

Authors present their work on the analysis of phenolic compounds using HPLC-DAD, however, methods already exist for the analysis of these compounds using GCMS as well as LCMS. Typically MS methods provide confidence in the analytes since we monitor the parent and daughter masses. HPLC methods typically rely on the UV. In complex matrices, this can be a huge issue with bias in analysis unless all the samples are spiked and analyzed for QA/QC. Authors have to provide a strong reasoning behind selecting the HPLC-based methods and compare the analyte recoveries to MS methods. Also, comment on the instrument and method detection limits in comparison to MS methods.

Author Response

I would like to express my sincere gratitude for your thorough review and evaluation of our manuscript. Your insightful suggestions and observations have greatly contributed to the improvement of our work. We truly value the time and effort you have dedicated to providing us with valuable feedback. Your expertise and attention to detail have been instrumental in enhancing the quality of our research. We are committed to addressing the points raised in your review and incorporating your suggestions to further enhance the clarity and impact of our manuscript. Once again, thank you for your invaluable contribution to our work. 

Authors' answer to the reviewer comment: 

Authors have chosen to use HPLC-DAD for the analysis of phenolic compounds due to its simplicity, ease of use, and cost-effectiveness compared to GC-MS and LC-MS methods. While MS methods offer the advantage of monitoring parent and daughter masses for increased confidence in analytes, HPLC-DAD can still be a reliable method for quantifying phenolic compounds. To address the potential bias in analysis, we conducted a recovery experiment to assess the accuracy of the HPLC-DAD method. This experiment involved comparing the measured concentrations of phenolic compounds in environmental samples to their known or expected concentrations, providing valuable information on the reliability of the method in determining the true concentration of the analytes. In our study, we compared the quantitation limits achieved by the HPLC-DAD method to those typically obtained by MS methods. The results demonstrated that the HPLC-DAD method provided quantitation limits rivaling those of more advanced MS techniques, indicating that our method is capable of accurate quantification of phenolic compounds in environmental samples. While MS methods offer unique advantages in terms of confidence in analyte identification, the HPLC-DAD method can still be a valuable tool for the analysis of phenolic compounds, especially when considering factors such as cost and ease of use. Our study highlights the robustness and reliability of the HPLC-DAD method for analyzing phenolic compounds and provides insights into its performance compared to MS methods.

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript of Paun et al. aims to develop a new monitoring method for quantified 17 phenolic compounds in surface water and wastewater with a DAD detector.

This manuscript would have been of interest for Environments due to its interesting general scope. Unfortunately the structure of the manuscript is very unusual, as it aims to develop a new method in which all the conditions are provided in the materials and methods section. Moreover, all the preparation procedure is very classical and standard (C18, mobile phase, stationary phase, etc) and has been published hundred of times. What's the innovation in your study? To answer what kind of questions? To be honest this manuscript looks like a technical report rather than a scientific article. You compare several analytical procedures, but you avoid to mention SPA-HPLC-DAD protocols that already exists especially in the food chemistry community. Please be more precise.

Due to the lack of scientific question, the lack of novelty in the analytical procedure, and the lack of precision in the determination of key parameters (the explanation of LOQ/LOD calculations is insufficient) I recomment to reject this manuscript.

 

Comments on the Quality of English Language

The manuscript is too verbose and language deserves for a proofread.

Author Response

I would like to express my sincere gratitude for your thorough review and evaluation of our manuscript. Your insightful suggestions and observations have greatly contributed to the improvement of our work. We truly value the time and effort you have dedicated to providing us with valuable feedback. Your expertise and attention to detail have been instrumental in enhancing the quality of our research. We are committed to addressing the points raised in your review and incorporating your suggestions to further enhance the clarity and impact of our manuscript. Once again, thank you for your invaluable contribution to our work.

Authors' response:

We appreciate the reviewer's feedback on our manuscript. Our study aimed to develop a new method for the analysis of phenolic compounds in water samples, focusing on comparing different analytical procedures commonly used for this application. While the materials and methods section may appear standard in terms of the stationary phase and mobile phase used, the novelty of our study lies in the optimization of these conditions specifically for the analysis of phenolic compounds in water samples.

The innovation in our study lies in the optimization and validation of the HPLC-DAD method for the rapid and accurate quantification of 17 phenolic compounds in water samples, using a simple-to-use and cost-effective method compared to LC-MS techniques, but with the same results for LOQs levels. We compared our proposed method with others specifically applied to the analysis of water samples, as this was the main focus of our research. While we did not explicitly mention SPE-HPLC-DAD protocols, we aimed to highlight the uniqueness of our method compared to existing techniques commonly used in the field.

Regarding the determination of key parameters such as limits of quantification (LOQ) and limits of detection (LOD), we acknowledge that further explanation and clarification are needed in the manuscript. We will revise the text to provide a more detailed description of the LOQ/LOD calculations.

Overall, our study addresses the important question of developing a reliable and efficient method for the analysis of phenolic compounds in water samples. We believe that the results of our research provide valuable insights into the optimized HPLC-DAD method for this specific application and contribute to the existing knowledge in the field of environmental analysis.

 

Reviewer 4 Report

Comments and Suggestions for Authors

In my opinion, the manuscript No. environments-2901273 by Paun et al. is well written, contains elements of scientific novelty, and presents the results that are of potential application for environmental monitoring. I have a few remarks for consideration by the authors to revise the manuscript.

1.      Lines 73-75 – the compounds analyzed by Paun et al. are not non-volatile or thermally labile and do not require derivatization for GC analysis (e.g. 10.1007/s11696-020-01398-6, 10.1016/0043-1354(96)00060-7).

2.      Line 112 – I suggest mentioning the methods.

3.      Line 162 – is it the correct subsection title?

4.      Caption to Figure 1 – I suggest indication of the flow rate in Figure 1a and indication of the wavelength in Figure 1b.

5.       Caption to Figure 2 – I suggest indication of the flow rate and wavelength.

6.      Caption to Figure 3 – I suggest including the optimal parameters in this caption or in the new Table.

Author Response

I would like to express my sincere gratitude for your thorough review and evaluation of our manuscript. Your insightful suggestions and observations have greatly contributed to the improvement of our work. We truly value the time and effort you have dedicated to providing us with valuable feedback. Your expertise and attention to detail have been instrumental in enhancing the quality of our research. We are committed to addressing the points raised in your review and incorporating your suggestions to further enhance the clarity and impact of our manuscript. Once again, thank you for your invaluable contribution to our work. 

Please find below the responses to your comments:

Q1. Lines 73-75 – the compounds analyzed by Paun et al. are not non-volatile or thermally labile and do not require derivatization for GC analysis (e.g. 10.1007/s11696-020-01398-6, 10.1016/0043-1354(96)00060-7).

A1. As mentioned in lines 73-75 of the manuscript, we also highlighted the non-volatile nature of the phenolic compounds studied. We acknowledge that there are chromatographic conditions, such as specific chromatographic columns, suitable for analyzing these compounds without derivatization; however, these conditions are less common. Additionally, while mass spectrometry can be used for the detection of these compounds, it often increases the cost of analysis. Our aim in this study was to develop a robust and cost-effective HPLC-DAD method for the analysis of phenolic compounds, considering the practicalities and cost implications associated with alternative analytical techniques.

 

Q2. Line 112 – I suggest mentioning the methods.

A2. The comment pertains to mentioning the method developed in this study.

 

Q3. Line 162 – is it the correct subsection title?

A3. No. Thank you for observation. We modified the sub section in ‘Sample collection’

 

Q4. Caption to Figure 1 – I suggest indication of the flow rate in Figure 1a and indication of the wavelength in Figure 1b.

A4. Modified accordingly

 

Q5. Caption to Figure 2 – I suggest indication of the flow rate and wavelength.

A5. Modified accordingly

 

Q6. Caption to Figure 3 – I suggest including the optimal parameters in this caption or in the new Table.

A6. Table 2 has been added

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have addressed my comments.

Author Response

Thank you to the reviewer for the positive feedback.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have performed minor modifications on their manuscript and failed to provide sufficient insights in the novelty of their study as well as a proper scientific question. Based on this, I cannot concur with the publication of the manuscript, even if I I can understand the choice of the editor.

Comments on the Quality of English Language

Some corrections have been performed but a proofread remains necessary.

Author Response

Dear Reviewer,

Thank you for your insightful feedback on our manuscript. We appreciate your suggestion to provide more insights into the novelty of our study and to pose a proper scientific question. Based on the information provided, we have revised the 'Strengths, limitations, and future work' section to emphasize the unique contributions and implications of our research. The present study introduces a novel multiwavelength HPLC-DAD method for the simultaneous determination of 17 phenolic compounds in water matrices. This method offers several advantages, including high sensitivity, accuracy, and a short chromatographic run-time. The quantification limits achieved in this study are comparable to those obtained through advanced LC-MS techniques, underscoring the exceptional sensitivity and precision of the developed method. One of the main strengths of our research lies in the significant improvement in the analytical method for quantifying phenolic compounds, overcoming previous limitations. The method's cost-effectiveness and ability to detect pollutants at low concentrations contribute to a comprehensive understanding of their presence and environmental impacts. The simplicity and efficiency of the method make it a valuable tool for routine monitoring in water quality management. Moving forward, future studies can expand on our research by analyzing a broader range of phenolic compounds and testing the method across diverse environmental settings. Long-term monitoring using this method can track trends in compound levels, identify contamination sources, and evaluate pollution control measures. We have enhanced the discussion on the novelty of our study and posed a proper scientific question that aligns with the significant advancements and implications of the developed HPLC-DAD method. These revisions aim to provide a clearer understanding of the unique contributions and potential scientific impact of our research on environmental analysis and water quality assessment.

Thank you for your valuable feedback, and we hope that the updated section adequately addresses your concerns.