PONE-D-20-29971

Poly(alizarin red S) modified glassy carbon electrode for square wave adsorptive stripping voltammetric determination of metronidazole in tablet formulation

PLOS ONE

Dear Dr. Amare,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================

Based on reviewers recommendations, the manuscript required extensive revision before consider it for the publication in journal.

==============================

Please submit your revised manuscript by Nov 30 2020 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Girish Sailor

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: No

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Review Report on “Poly (alizarin red S) modified glassy carbon electrode for square wave adsorptive stripping voltammetric determination of metronidazole in tablet formulation”

Manuscript Number: PONE-D-20-29971

The authors have given detailed information for the detection of metronidazole by glassy carbon electrode modified with electro-polymerized alizarin red S. The work lacks novelty and needs more issues to be addressed as follows:

A. ABSTRACT

1. Typo-errors should be adjusted along the whole manuscript.

2. SEM images of bare and unmodified GCE should be added.

3. R2 should be four decimal points.

4. Simple abbreviations should be used along the manuscript such as current should be Ipc, scan rate should be ν and ---------so on.

5. Recoveries % should be one decimal points for example 96.15% should be 96.2%

6. Line 20, in the presence of 100 and 150% of uric acid and ascorbic acid. Please omit these values and replace by concentrations.

7. What is meant by complex matrix? Why the authors did not quantify metronidazole in biological matrices such as urine and plasma.

8. What is meant by charge transfer controlled?

B. INTRODUCTION

9. Scheme 1 should be removed. The structure of metronidazole is already described in the reduction mechanism.

10. Metronidazole should be properly abbreviated as MTZ along the manuscript.

11. Thus, development of a simple, cost effective, and sensitive method for determination of MTZ in samples like tablet formulation is still vital. Please omit “like tablet formulation”.

12. The authors should add a simple paragraph about the importance of polymers in the fabrication of electrodes, and the following papers for references that force this section:

https://doi.org/10.1016/j.msec.2017.02.092, https://doi.org/10.1007/s00216-019-02245-8, https://doi.org/10.1002/elan.201700078, https://doi.org/10.1016/j.colsurfa.2019.01.033

13. Lines 73-75 not correct and should be corrected i.e. what is meant by glassy carbon electrode is widely used due to its biocompatibility with tissue (incorrect statement) and minimal propensity to show deteriorated response as a result of electrode fouling (not correct as the GCE itself cannot prevent fouling itself but the some modifier on its surface prevents its fouling).

III. EXPERIMENTAL

14. Abbreviations such as PARS and ARS should be defined at start i.e. ABSTRACT.

15. Term MET instead of metronidazole should be unified along the revised manuscript.

16. Concentration of supporting electrolyte in reference electrode should be mentioned.

17. Section 2.5, 10 mM should be replaced by amount in grams.

18. The authors should perform MET analysis in more interfering samples such as urine and plasma.

IV. RESULTS AND DISCUSSIONS

19. In Fig.1, to prove the stability of poly (alizarin S) on the surface of GCE, multiple CV scans should be provided on inset of Fig.1.

20. Accumulation time should be added to Fig.2.

21. Surface areas of bare and modified GCE should be calculated.

22. Scan rate should be unified along the manuscript either mV/s or mV s-1.

23. Figs. 5 and 6 should be merged in one Figure.

24. Line 257, R2 is determination coefficient not correlation coefficient.

25. What is the relationship between R2 and type of analyte transfer during electroanalysis (lines 257-260?

26. “Slope value of 0.38, which is less than the ideal value of 0.5 for plot of log Ip versus log ʋ (Fig. 9), further confirmed participation of both with adsorption as the predominant”. This is incorrect as slope near to 0.5 means diffusion controlled process while near to 1.0 means adsorption controlled. Please, use these references as a guide.

https://doi.org/10.1016/j.bios.2018.03.015, https://doi.org/10.1016/j.molliq.2018.08.105, https://doi.org/10.1016/j.bios.2019.111849

27. Fig.8, what is meant by SQRT?

28. Figs. 7, 8 and 9 should be merged in one Figure.

29. Accumulation time should be added to Fig.10.

30. Fig.11 represents calibration plot of MTZ in bulk or tablet. Please, specify.

31. Please, replace SWAdCSV by SWV.

32. Method should be compared with a reference method.

33. Why the authors tested selectivity of the electrode using only ascorbic and uric acids, although they performed their analysis if pharmaceutical formulations that include other excepients such as glucose, sucrose, Mg-stearate, maltose, starch and others. Ascorbic and uric acids are substances mainly present in biological samples. So, it is preferred to carry out analysis in biological fluid e.g. plasma

34. Figs. 12 and 13, replace SWSV by SWV.

35. Caption of Table 3, replace metronidazole with MTZ.

36. To Table 3, add samples analyzed.

37. Table 3, replace DPSV by DPV.

V. CONCLUSION (S)

38. Conclusion part should be shortened and contains all corrected issues raised by the reviewer.

39. Replace metronidazole by MTZ in conclusion part.

Reviewer #2: The results presented by the authors are important to understand a novel way to determine metroimidazole by voltammetry method using a modified electrode which is quite important. The findings are interesting. There are some minor revisions upon.

1. Please read MS carefully there are some minor grammar mistakes.

2. Insert the error bars in Figure 6 and 11.

3. The conclusion should be concise and highlighted the obtained results.

Reviewer #3: The manuscript introduced a stripping voltammetric method for the determination of

metronidazole in tablet sample based on the poly(alizarin red s) modified GCE. Although the method is simple, however, the author has not pointed out the advantages of it, when compared with other electrochemical methods for the determination of metronidazole. And the following questions should be considered by the author：

1. In line 106 and 107, “working” and “reference” can not be fully expressed, it should be replaced by professional terms such as working electrode, reference electrode.

2. The morphology of poly alizarin red material should be characterized by SEM if possible.

3. Some typing error should be corrected.

4. Table 2 should be represented by a three line table.

5. For the explanation of inner probes, it is better to compare the electrochemical behavior of outer probes such as ruthenium ammonia. In addition, some References is need to explanation the inner probes. For example, the article of Richard L. McCreery, https://pubs.acs.org/doi/abs/10.1021/ac960492r.

6. Error bars should be added to the calibration curve of Ic to c.

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Reviewer #1: Yes: Dr. Mohamed M. El-Wekil

Reviewer #2: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachments

Attachment

Submitted filename: Reviewer suggestions for manuscript No. PLOS-D-20-29971.docx

PONE-D-20-29971R1

Poly(alizarin red S) modified glassy carbon electrode for square wave adsorptive stripping voltammetric determination of metronidazole in tablet formulation

PLOS ONE

Dear Dr. Amare,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================

The reviewer has suggested certain minor correction in revised manuscript before publication. 

==============================

Please submit your revised manuscript by Jan 09 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Girish Sailor

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #3: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Manuscript Number: PONE-D-20-29971 R1

The authors have given detailed information for the detection of metronidazole by glassy carbon electrode modified with electro-polymerized alizarin red S. The work can be accepted after addressing the following:

In General: the abbreviations along the revised version should be used properly such as metronidazole should be MTZ, cyclic voltammetry should be CV and square wave voltammetry----etc.

A. ABSTRACT

1. Lines 9-10, with three-folds of current enhancement at the modified GCE. Compared to what?

2. Lines 13-15, this sentence should be adjusted.

3. Lines 20 and 21, concentration units of ascorbic and uric acids should be added.

4. Line 25, with complex matrix should be removed. Most tablets contain electro-inactive species, while biological samples contain more interfering species.

B. INTRODUCTION

5. Line 46, scheme1 should be removed.

6. The novelty of the manuscript is still unclear. The authors should force the readers’ attention via stressing on the novelty of the method compared to others.

B. EXPERIMENTAL

7. Internal diameter of GCE should be added.

8. Line 126, 5 mM should be 5.0 mM.

9. Line 127, 1mM should be 1.0 mM.

B. RESULTS AND DISCUSSIONS

10. Calculation of effective surface areas of GCE and modified GCE should be added.

11. Reproducibility and stability of PARS/GCE should be addressed.

12. To show accuracy of the method, it should be compared with reported method.

Reviewer #3: The manuscript introduced a stripping voltammetric method for the determination of

metronidazole in tablet sample based on the poly(alizarin red s) modified GCE. Some minor problems still exist and the author should examine the manuscript carefully and revise it：

1. In line 110 in the PONE-D-20-29971-R1, “Ag/AgCl (3 M KCl) as reference” should be replaced by professional terms such as reference electrode.

2. Table 2 still needs to be modified and it should be on the same page. The form of the table 2 is as shown in Table 3.

3. Incorect sentence and typing error still exist. Please check it carefully and correct it. For example, “0.98830 and 0.97398” in line 261, “[32 33.” in line 264 in the PONE-D-20-29971-R1.

4. Some superscripts and subscripts should be carefully checked and revised.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachments

Attachment

Submitted filename: Reviewer suggestions for manuscript No. PLOS-D-20-29971R1.docx

Poly(alizarin red S) modified glassy carbon electrode for square wave adsorptive stripping voltammetric determination of metronidazole in tablet formulation

PONE-D-20-29971R2

Dear Dr. Amare,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Girish Sailor

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: (No Response)

Reviewer #3: (No Response)

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #3: (No Response)

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #3: (No Response)

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #3: (No Response)

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #3: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #3: No