Development, Validation and Application of a Targeted LC-MS Method for Quantification of Microcystins and Nodularin: Towards a Better Characterization of Drinking Water

Round 1

Reviewer 1 Report

Manuscript Number: water-1652215

Development, validation and application of a targeted LC-MS method for quantification of microcystins and nodularin: towards a better characterization of drinking water.

GENERAL COMMENTS

This is the start-up and validation of a method for the determination of microcystins and nodularins in drinking water. I believe that it is a very topical topic, which attends to an increasingly growing demand for this type of method for the determination of more and more contaminants in drinking water.

It seems to me that the article should be accepted in the present form.

I just have a few questions for the authors,

Does this type of toxin cause any harmful effect on other types of living beings besides humans, for example fish? And in that case, could this method be applied to another type of matrix, for example to seawater in order to control that this type of toxin does not affect marine fauna?

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,

Send you the Review on the manuscript “Development, validation and application of a targeted LC-MS method for quantification of microcystins and nodularin: towards a better characterization of drinking water”.

Thank you for theactual,  interesing and well designed investigation. 

As one of the main remarks, I will note the need to supplement the manuscript with additional figures for a better understanding of the material presented and the expansion of the Conclusions section. In its current form, this section poorly reflects the main conclusions that the authors made from the results of the study. There are other comments, which are given in the attached file.

 

Comments for author File: Comments.docx

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Abstract:

L18: lack a “.” after microcystin

Introduction:

L38 – L39: is something lacking in-between the two lines?

L53: The sentence about cylindrospermopsin: “Cylindrospermopsin’s (CYN) mode of action is to inhibit protein synthesis and they initially target the liver, potentially causing damage [13,14].” Seem a little out of place, since they are never mentioned again in the manuscript and is not linked to following. So, either leave out (or mention together with all the other cyanotoxins also).

L90: PPIA and ELISA – are they really so similar that it is correct to say that they have the same shortcomings?

L96-97: Would think that the need for pure standards for each specific congener is a major shortcoming for LC-methods. Considering there are quite a few possible MCs.

L130: Why did you adjust to pH 11?

Figure 2: A little hard to read. Numbers are very small. Could the axis be simplified? Are “00” needed after the point on the y-axis. The table about matrix effects – is it needed here or could it just be stated in one sentence in the text in the caption? The title – the normal is to have such title as part of the caption and not in the actual figure. Suggest remove and maybe add drinking water in the first sentence in the caption.

L266: Table 1 – a second table 1? Number of decimals needed for recovery in percentage? Are they all actually giving needed information or would it be enough without the decimals?

L283: Is this table 3?

Conclusions

L382: Wonder if the conclusion is too generalized here considering only nine analogues were analyzed? Most likely it is safe, but still you cannot say anything about the ones not included in the analysis, can you?

L384-386: 6. Patents – looks like a standard text, that is not needed here?

References

Titles of papers referred to have capital letters in “all” first letters of all words. The styles are usually small letters, as in a normal sentence, unless in Names and so on.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

1. Line 251: Figure 2: Matrix effect assessment for the different microcystin congeners and nodularin. The presence of a matrix effect was established by comparing the difference in slope based on a student t-test. Is it possible to show the value of student t-test in Fig. 2?
2. Line 253-255: “Moreover, the LOD (0.1 µg L-1) and LOQ (0.5 µg L-1) for all nine toxins had a ratio of signal to noise higher than 3 and 10, respectively, as shown in Table 2.” Is it in Table 1 not in Table 2? Please check it again.
3. Line 255-256: The recovery for MC-LF, MC-LW and MC-WR were below the acceptable limit of 70.0% (Table 2). It is necessary to explain this results more detail.
4. Line 260: “The recoveries for the conform toxins ranged from 83.0% to 98.7% on average (Table 2).” I didn’t find these values in Table. Is it wrong?
5. Line 262-263: “MU’s for all the MCs and NOD were calculated to be between 10.0% and 42.1% (Table 2).” Is it in Table 1? It is so confused.
6. Line 263-265: “The average variance (repeatability) and CV (reproducibility) for all the MCs and NOD were within the bounds set by the Horwitz ratio, 14.7% and 22.0%, respectively (Table 2).” Is it in Table 1? It is wrong.
7. There are two Table 1 and one Table 2. Please correct it.
8. Line 330-331: In Discussion. Overall recoveries for MC-WR, MC-LF and MC-LW were lower than for the other toxins. Please explain their reasons.

Author Response

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Author Response File: Author Response.docx