Electrochemical Sensors for Determination of Bromate in Water and Food Samples—Review
Round 1
Reviewer 1 Report
The paper reviews electrochemical sensors developed for the determination of bromate ions in water samples. Although the paper is well organized and written, it needs to be revised before publication. The authors present the WHO and USEPA recommended concentration of bromate in water to be 80 nM or 10 µg/L . Several references cited within the text present higher LOD than the reccomended maximum concentration in water. In a review, I believe the papers cited should attend to this specification as it provides proper contextualization of the viable sensors developed so far. Therefore, my suggestions are:
- Papers cited should present LOD within the USEPA and WHO BrO3- recommendation, up to 80 nM. Please revise the entire text and substituting/removing references which are not suitable for bromate determination within the regulatory agencies limits.
- ‘Graphical abstract, figure 3, 6 and 7 should present better resolution/ratio avoiding distortions.
- Page 14 line 453: How the linear range low limit present a lower value than the LOD?
- The introduction should discuss the usual electrochemical pathway of a bromate electrochemical reaction. How many electrons are involved in the bromate reduction? Is the final product bromide ions? Or the final product is different according to the solution pH value?
- Page 16 line 531 “An EIS sensor for the detection of AA was… This sensor was applied for urine analysis for BrO3- with good recovery.” AA means ascorbic acid? I don’t understand if the sensor was developed for AA or BrO3-. Please correct it accordingly
Author Response
The Editor
Biosensors
REVISION OF MANUSCRIPT SUBMITTED FOR PUBLICATION
Manuscript Title: Electrochemical Sensors for Determination of Bromate in water and food Samples – Review
Manuscript ID: biosensors-1193448
We thank you for the reviewers' reports on our review manuscript, and we as a result of this submit the revised version for further consideration. The comments indeed have improved the quality of our paper.
We have responded point by point, according to the reviewers. All the comments and suggestions from reviewers have been carefully considered and treated accordingly.
Please find below, authors' responses to the reviewers' comments and suggestions. Comments and recommendations from the reviewers are written first with the heading "Reviewer's comment" followed by authors' responses with the heading "Authors' response". Kindly also note that the revised areas of the manuscript are highlighted yellow in the revised manuscript.
Reviewer 1
Comments and Suggestions for Authors
The paper reviews electrochemical sensors developed for the determination of bromate ions in water samples. Although the paper is well organized and written, it needs to be revised before publication. The authors present the WHO and USEPA recommended concentration of bromate in water to be 80 nM or 10 µg/L . Several references cited within the text present higher LOD than the recommended maximum concentration in water. In a review, I believe the papers cited should attend to this specification as it provides proper contextualization of the viable sensors developed so far. Therefore, my suggestions are:
- Papers cited should present LOD within the USEPA and WHO BrO3-recommendation, up to 80 nM. Please revise the entire text and substituting/removing references which are not suitable for bromate determination within the regulatory agencies limits.
Authors' response: Most of the cited references with greater LOD than USEPA and WHO recommendation have been replaced, except few that are a little bit higher. Meanwhile, the 80 nM maximum acceptable limit by USEPA and WHO is specifically for drinking water.
- ‘Graphical abstract, figure 3, 6 and 7 should present better resolution/ratio avoiding distortions.
Authors' response: Thanks for the comment. Graphical abstract and figure 7 have been removed while figures 3 and 6 resolution have been improved. See yellow highlight on pages 10 and 16 of the manuscript.
- Page 14 line 453: How the linear range low limit present a lower value than the LOD?
Authors' response: The LOD is in nM while the linear range is in μM i.e the LOD is 0.17 nM (0.00017 μM ) and the linear range is 0.04-0.35 μM.
- The introduction should discuss the usual electrochemical pathway of a bromate electrochemical reaction. How many electrons are involved in the bromate reduction? Is the final product bromide ions? Or the final product is different according to the solution pH value?
Authors' response: Thanks. Electrocatalytic reaction of bromate has been included, likewise the reduction pathway. See yellow highlight on pages 2 - 3 of the manuscript.
- Page 16 line 531 “An EIS sensor for the detection of AA was… This sensor was applied for urine analysis for BrO3- with good recovery.” AA means ascorbic acid? I don’t understand if the sensor was developed for AA or BrO3-. Please correct it accordingly
Authors' response: Thanks for your comment. The paragraph is describing other applications of EIS in Ascorbic acid detection, not bromate. The paragraph has been improved. See yellow highlight on pages 16 of the manuscript.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Balogun et al. in this manuscript present a timely review to summarize recent progress in the field of bromate detection using electrochemical methods. The authors discuss different detection methods and electrode materials widely used for sensing bromate in the water and food samples. Overall, the manuscript is clear, and all citing figures are self-explanatory. I would suggest accepting this manuscript after the authors have adequately addressed the following remarks.
- A general question about the frame of this review: the authors divide the topic into two parts. One is focused on the detection method; the other is the electrode material. While only section 7 has a subheading related to the detection method. The authors could better balance the content of each part.
- Spectrophotometry is not an electrochemical technique. The authors need to address this discrepancy in the manuscript or change it to a related term, like spectroelectrochemistry.
- Address the inaccurate citation of some references. I only checked the introduction section. For example, ref.4 doesn't mention the maximum acceptable bromate. Ref. 11 is not related to the electrochemical method for bromate determination. The authors need to check all references across the manuscript for consistency.
- The authors need to address the inappropriate discussion of previous research works in the wrong section. This happens several times across the manuscript. For example, on page 3, the last paragraph is from a paper using CNT as the substrate for bromate detection. It belongs to the next section.
- It is better to sort Table 1 based on either detection method, substrate materials, or detection performance. The current version is less organized.
Author Response
The Editor
Biosensors
REVISION OF MANUSCRIPT SUBMITTED FOR PUBLICATION
Manuscript Title: Electrochemical Sensors for Determination of Bromate in water and food Samples – Review
Manuscript ID: biosensors-1193448
We thank you for the reviewers' reports on our review manuscript, and we as a result of this submit the revised version for further consideration. The comments indeed have improved the quality of our paper.
We have responded point by point, according to the reviewers. All the comments and suggestions from reviewers have been carefully considered and treated accordingly.
Please find below, authors' responses to the reviewers' comments and suggestions. Comments and recommendations from the reviewers are written first with the heading "Reviewer's comment" followed by authors' responses with the heading "Authors' response". Kindly also note that the revised areas of the manuscript are highlighted yellow in the revised manuscript.
Reviewer 2
Comments and Suggestions for Authors
Balogun et al. in this manuscript present a timely review to summarize recent progress in the field of bromate detection using electrochemical methods. The authors discuss different detection methods and electrode materials widely used for sensing bromate in the water and food samples. Overall, the manuscript is clear, and all citing figures are self-explanatory. I would suggest accepting this manuscript after the authors have adequately addressed the following remarks.
- A general question about the frame of this review: the authors divide the topic into two parts. One is focused on the detection method; the other is the electrode material. While only section 7 has a subheading related to the detection method. The authors could better balance the content of each part.
Authors' response: The session 3 discusses detection methods along with the electrode materials. The detection methods and electrode materials have discussed simultaneously in the paragraphs.
- Spectrophotometry is not an electrochemical technique. The authors need to address this discrepancy in the manuscript or change it to a related term, like spectroelectrochemistry.
Authors' response: Thanks for the comment. All the spectrophotometric techniques have been removed/replaced with electrochemical techniques. See yellow highlight on page 15 of the manuscript, i.e from the table.
- Address the inaccurate citation of some references. I only checked the introduction section. For example, ref.4 doesn't mention the maximum acceptable bromate. Ref. 11 is not related to the electrochemical method for bromate determination. The authors need to check all references across the manuscript for consistency.
Authors' response: The incorrect references have been removed and replaced with the correct ones. REF. 4 now reflects the maximum acceptable bromate and REF. 11 is now relating to the electrochemical method for bromate determination and ditto to others. See page 18 of the manuscript
- The authors need to address the inappropriate discussion of previous research works in the wrong section. This happens several times across the manuscript. For example, on page 3, the last paragraph is from a paper using CNT as the substrate for bromate detection. It belongs to the next section.
Authors' response: Correction made; each paragraph has been properly arranged based on Sensor material. See yellow highlight on pages 4 -13 of the manuscript
- It is better to sort Table 1 based on either detection method, substrate materials, or detection performance. The current version is less organized.
Authors' response: Correction made; the table has been adjusted to accommodate reviewer’s suggestions. See yellow highlight on page 15 of the manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript submitted to Biosensors entitled “Electrochemical Sensors for Determination of Bromate in water and food Samples – Review” by Balogun et al. presents a concise review on bromate electrochemical detection systems developed in recent years. The subject is interesting and is a welcome addition to the present in the literature. However, this manuscript requires extensive improvements before publication.
In general, this revision is highly descriptive without any comparison and discussion on the works here described.
Section 8 is entirely off-topic. Phthalocyanines have application in a wide array of detection applications. However, if they are not used in the electrochemical detection of bromate ions, they do not add any value to the current manuscript.
Furthermore, many other aspects should be improved and clarified in this review. For instance:
1) The significant advantages of electrochemical sensors over any other kind of sensors, such as optical sensors and spectrophotometric methods, should be discussed in the introduction.
2) This review only describes direct results on the bromate ions indicating LODs and linear concentration relationships. Looking carefully at the articles here referenced, most of these studies comprehend much more detailed results concerning the role of interfering ions and real sample testing. This information should be compiled, highlighted and discussed whenever possible. This information is probably the most helpful information a review can deliver to a reader.
3) The figures used in general have low quality and should be replaced with better quality figures.
5) Please discuss the stability and reusability of the sensors if possible. Also, the electrochemical sensors here described should be compared whenever possible.
5) Please discuss possible future directions for the subject and give a personal perspective on the matter.
6) The title refers to food and water samples. However, this is not clear in the manuscript. Which sensors are used for food, and which ones are used for water? Please clarify.
7) Table I should be organized by the electrochemical mode, or perhaps the references could be organized by sample (food or water samples).
8) In line 548 the authors state that phthalocyanines have 18 pi electrons. That is correct, but it has a nuance. Its 18 pi electrons in the shortest conjugation pathway. If all the pi electrons are accounted the number will be much higher than 18. Please change in accordance.
9) please be careful with typos and misspellings. For instance:
Line 42: ab1.ound.; meaning?
Line 252: μAmM-1cm-2; spaces between units.
Lines 284, 285 and 286: Place the beta symbol in italic.
Thank you
Author Response
The Editor
Biosensors
REVISION OF MANUSCRIPT SUBMITTED FOR PUBLICATION
Manuscript Title: Electrochemical Sensors for Determination of Bromate in water and food Samples – Review
Manuscript ID: biosensors-1193448
We thank you for the reviewers' reports on our review manuscript, and we as a result of this submit the revised version for further consideration. The comments indeed have improved the quality of our paper.
We have responded point by point, according to the reviewers. All the comments and suggestions from reviewers have been carefully considered and treated accordingly.
Please find below, authors' responses to the reviewers' comments and suggestions. Comments and recommendations from the reviewers are written first with the heading "Reviewer's comment" followed by authors' responses with the heading "Authors' response". Kindly also note that the revised areas of the manuscript are highlighted yellow in the revised manuscript.
Reviewer 3
Comments and Suggestions for Authors
The manuscript submitted to Biosensors entitled “Electrochemical Sensors for Determination of Bromate in water and food Samples – Review” by Balogun et al. presents a concise review on bromate electrochemical detection systems developed in recent years. The subject is interesting and is a welcome addition to the present in the literature. However, this manuscript requires extensive improvements before publication.
In general, this revision is highly descriptive without any comparison and discussion on the works here described.
Section 8 is entirely off-topic. Phthalocyanines have application in a wide array of detection applications. However, if they are not used in the electrochemical detection of bromate ions, they do not add any value to the current manuscript.
Authors' response: Thanks for the comment. Section 8 has been removed. See page 17 of the manuscript.
Furthermore, many other aspects should be improved and clarified in this review. For instance:
1) The significant advantages of electrochemical sensors over any other kind of sensors, such as optical sensors and spectrophotometric methods, should be discussed in the introduction.
Authors' response: Thanks. The advantages of electrochemical techniques over other techniques has been included. See yellow highlight on pages 2 and 3 of the manuscript.
2) This review only describes direct results on the bromate ions indicating LODs and linear concentration relationships. Looking carefully at the articles here referenced, most of these studies comprehend much more detailed results concerning the role of interfering ions and real sample testing. This information should be compiled, highlighted and discussed whenever possible. This information is probably the most helpful information a review can deliver to a reader.
Authors response: Information on interfering ions and real sample testing have been included. See yellow highlight on pages 4, 6, 7, 9, 12, 13 and 14 of the manuscript.
3) The figures used in general have low quality and should be replaced with better quality figures.
Authors' response: Thanks for the brilliant observation. The quality of figures has been improved. See yellow highlight on the manuscript.
5) Please discuss the stability and reusability of the sensors if possible. Also, the electrochemical sensors here described should be compared whenever possible.
Authors' response: Stability and reusability have been discussed. See yellow highlight on pages 4, 5, 6, 7, 8, 9, 11, 12 and 13 of the manuscript.
Comparison between the electrodes have been included. See yellow highlight on pages 4, 6, 9, 11 and 13 of the manuscript.
5) Please discuss possible future directions for the subject and give a personal perspective on the matter.
Authors' response: Possible future directions and personal perspective have been included. See yellow highlight on pages 15 and 17 of the manuscript
6) The title refers to food and water samples. However, this is not clear in the manuscript. Which sensors are used for food, and which ones are used for water? Please clarify.
Authors' response: The type of sample has been indicated in the paragraphs, likewise on table 2. See yellow highlight on pages 4, 5, 6, 7, 9, 10 and 14 of the manuscript.
7) Table I should be organized by the electrochemical mode, or perhaps the references could be organized by sample (food or water samples).
Authors' response: The table has been rearranged to accommodate sensor category, modified electrode, techniques, sample, linear range, detection limit and reference. See yellow highlight on pages 15 of the manuscript
8) In line 548 the authors state that phthalocyanines have 18 pi electrons. That is correct, but it has a nuance. Its 18 pi electrons in the shortest conjugation pathway. If all the pi electrons are acounted the number will be much higher than 18. Please change in accordance.
Authors' response: The paragraphs on phthalocyanines have been removed based on the reviewer’s suggestion.
9) please be careful with typos and misspellings. For instance:
Line 42: ab1.ound.; meaning?
Authors' response: It has been corrected – It was a typographical error. The correct word is abound. See yellow highlight on page 2 of the manuscript
Line 252: μAmM-1cm-2; spaces between units.
Authors' response: Spaces have been inserted in between units i.e µA mM-1 cm-2. See yellow highlight on page 8 of the manuscript.
Lines 284, 285 and 286: Place the beta symbol in italic.
Authors' response: All the ‘beta’ signs have been changed to italic. See yellow highlight on page 9 (lines 315 and 317) of the manuscript
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscript is now suitable for publishing. Congratulations on your work.
Author Response
Thanks for the comment.
Regards
Reviewer 2 Report
The manuscript has been greatly improved in response to my comments and suggestions, and it is worthy of publication.
Author Response
Thanks for the comment.
Regards
Reviewer 3 Report
Overall the manuscript quality has increased, and the author did an excellent job addressing most of my concerns.
However, I still have a few suggestions. For instance:
1) Every time the authors state that the sensor is selective in the presence of interferents, they should provide this information between parenthesis. It is a lot easier for the reader to understand the information on the manuscript.
2) Figure 3 still lacks quality. If possible, please try to improve this. Figures are nowadays a vital part of review articles and should be addressed with care.
Thank you
Author Response
The Editor
Biosensors
REVISION OF MANUSCRIPT SUBMITTED FOR PUBLICATION
Manuscript Title: Electrochemical Sensors for Determination of Bromate in water and food Samples – Review
Manuscript ID: biosensors-1193448
We thank you for the reviewers' reports on our review manuscript, and we as a result of this submit the revised version for further consideration. The comments indeed have improved the quality of our paper.
We have responded point by point, according to the reviewers. All the comments and suggestions from reviewers have been carefully considered and treated accordingly.
Please find below, authors' responses to the reviewers' comments and suggestions. Comments and recommendations from the reviewers are written first with the heading "Reviewer's comment" followed by authors' responses with the heading "Authors' response". Kindly also note that the revised areas of the manuscript are highlighted yellow in the revised manuscript.
REVIEWER COMMENTS
- Every time the authors state that the sensor is selective in the presence of interferents, they should provide this information between parenthesis. It is a lot easier for the reader to understand the information on the manuscript.
Authors' response: The interferents have been indicated with parentheses in the following pages and lines;
Page 5 line 170 – 172
Page 6 line 226 – 228
Page 7 line 244 – 246
Page 7 line 263 – 265
Page 9 line 332 – 334
Page 10 line 342 – 343
Page 11 line 395 – 397
Page 13 line 464 – 467
Page 14 line 501 – 503
- Figure 3 still lacks quality. If possible, please try to improve this. Figures are nowadays a vital part of review articles and should be addressed with care.
Authors' response: Figure 3 resolution has been improved. See page 10
Author Response File: Author Response.pdf
