Residue Analysis and Dietary Risk Assessment of Metalaxyl in Chinese Bayberry and Dendrobium officinale
Round 1
Reviewer 1 Report
The study was carried out to determine metalaxyl residues in minor crops from China and to assess dietary risk. For this purpose, the QuEChERS method coupled to GC-MS/MS was applied.
In my opinion, this type of study is not new. There are many similar studies applied to a wide variety of crops and pesticides, including metalaxyl. In any case, the authors only studied a single pesticide despite stating that: “Since Chinese bayberry and D. officinale are classified as minor crops, only a few agricultural chemicals are registered to control plant diseases and pest infestations in the process of cultivation” (lines 44-46). Many pesticides could have been analyzed simultaneously using the QuEChERS method combined with GC-MS/MS.
It should be also noted that the authors did not optimize the sample preparation method. In this sense, although the recoveries were good, the matrix effect was appreciable. So, different combinations of salts in the d-SPE step must have been studied.
With all of the above, I firmly believe that this manuscript is not suitable for publication in a Q1 journal.
Other minor comments:
What is the importance of these crops in commercial terms (production and export)? I assume there is no MRL for metalaxyl or any other pesticide.
"Although metalaxyl is not registered, previous investigation revealed that it is widely used in Chinese bayberries and D. officinale” (line 59), but the authors did not cite these studies or provide additional information.
GC-MS/MS instead GC-MS.
QuEChERS instead QuEChERs (Lines 78 and 97).
How many replicates were performed at each concentration level in the recovery study?
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Pesticides are widely used in the process of crop protection causing environmental and food safety problem. Hence, it is necessary to consider the toxic impact on human health and the environment. Consequently, it is essential to evaluate fate, residue levels, and risk assessment of pesticides in various fruits and vegetables. In this study the authors propose the analytical method for determination of metalaxyl in two matrices: Chinese bayberry and fresh and dried Dendrobium officinale, using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). Moreover, authors assess the dietary risks to consumer based on obtained residue levels. The results of these studies may be relevant only in Asian countries where such products are consumed. Reviewer has minor comments and after corrections manuscript can be published in Agronomy.
According to the reviewer this Article is well prepared. The reviewer has some suggestions for the text:
1. The linearity was set at a range of 0.001-0.1 mg/L and the fortification were performed at the highest concentration level of 2 mg/kg. Why? Spiking levels should be included in the linearity.
2. In the Materials and Methods part LOQ was defined at 0.001 mg/L, and in Results at 0.01 mg/kg. This should be clarified.
3. In the Residues of Metalaxyl in different matrices part authors give average values pesticides in investigated matrices at the level: 0.0657, 0.0558, 0.212 mg/kg but in the next part the values are different.
4. Table 3 is completely unreadable. Contains blank fields. The authors say they calculate the risk probability of metalaxyl for Chinese Bayberry and Dendrobium officinale, but filled the tables with other foods.
Moreover, the consumer exposure to pesticide residues should be assessed in accordance with the recommendations published by the World Health Organization and taking into account the Community procedures and practices. In Europe EFSA introduced a revised model for calculating the consumer exposure (PRIMo). The model was developed to calculate the dietary exposure to pesticide residues in food according to internationally agreed methodologies.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
In general, the concept of the presented research is interesting. The manuscript is well written and generally well organized. However, despite the interesting aim of the conducted research, I would like to highlight that the presentation of the obtained results is very scarce. I suppose the authors did a lot of laboratory work to elaborate and validate the sample preparation step, separation and detection procedure, and real samples analysis, but all these activities are not visible in the present form of the manuscript. Moreover, I should also emphasize that it is an analysis of only one compound, which is quite poor from an analytical point of view.
L:58 add acronyms to the other detectors and analytical techniques mentioned above
L66, 96, 133, 135: abbreviations must be explained at first use
L:92 Were the samples washed before storage?
L102: what gas was used for evaporation?
L122: instead "to bring the metalaxyl in the blank sample" use the blank sample was spiked with working solution …
L127: What criteria were considered for ME evaluation?
L143: what does "the risk of metalaxy is unacceptable" mean?
As this work is aimed at the elaboration and validation of analytical procedure I suggest adding any chromatograms obtained during this research. I wonder, there was no analyte peak in blank sample? Moreover, I would expect a more detailed presentation and discussion of results obtained from real samples. Currently, this part is very scarce.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 4 Report
This paper is aimed to evaluate the level of metalaxyl residue in fresh or dried fruit using GC-MS
However, through the simple search, I saw several paper that speak about the analysis of metalaxyl by GC-MS.
Could you please indicate what’s new in your work comparing with other papers that published already ?
Thank you very much for your efforts. and have a good luck in the next submission
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The manuscript has improved slightly, but the problem with this work is its scope. In fact, the authors have further highlighted this problem in their answers:
- They have clarified that there are specific MRLs for at least a dozen pesticides in these matrices. Why weren't all these pesticides determined simultaneously? This would have been easy considering the sample preparation method and instrumental system used. It should be noted that the other reviewers have also pointed in the same direction.
- The study now cited by the authors on the analysis of pesticides in D. officinale included 12 pesticides (reference 21). Of course!
In my opinion, if the main aim of this work is to assess the dietary risk to consumers based on food consumption data of Chinese bayberries and D. officinale and the residue levels, all pesticides applied to this crop, or at least most of the ones that have specific MRLs, should have been included in this study, but not just one.
On the other hand, the authors now indicate that they tested different combinations of salts in the clean-up step, but they do not show the data.
Author Response
Point 1: Why weren't all these pesticides determined simultaneously? This would have been easy considering the sample preparation method and instrumental system used. In my opinion, if the main aim of this work is to assess the dietary risk to consumers based on food consumption data of Chinese bayberries and D. officinale and the residue levels, all pesticides applied to this crop, or at least most of the ones that have specific MRLs, should have been included in this study, but not just one.
Response 1: Thank you for this valuable feedback. From the point view of sample preparation and instrument, it is easy for us to analyse multi-residues of pesticides in Chinese bayberries and D. officinale. But we only analyse the metalaxyl, we can clarify whether its application will pose a health risk to the general population. If the dietary risk assessment of multi-residues of pesticides is unacceptable, we cannot judge the application of metalaxyl is reasonable or not in agriculture.
Point 2: On the other hand, the authors now indicate that they tested different combinations of salts in the clean-up step, but they do not show the data.
Response 2: As suggested, we have supplemented a figure of different combination of dispersive solid phase extraction in supporting materials.
Reviewer 3 Report
I do not recommend this manuscript. The quality of this paper from an analytical point of view is poor, even after proofreading. The quality of the presented chromatograms is not acceptable.
Author Response
Point 1: The quality of this paper from an analytical point of view is poor, even after proofreading.
Response 1: In our study, we pay our attention on the chronic and acute dietary assessments, so the analytical method of metalaxyl section is a light sketch and simple writing.
Thank you very much for pointing out the problem and we have added the data we optimize different combinations of dispersive solid phase extraction in the clean-up step, and the figure is in supporting materials.
Point 2: The quality of the presented chromatograms is not acceptable.
Response 2: Thank you for this valuable feedback. As suggested, we have revised the chromatograms in supporting materials.
Reviewer 4 Report
Thank you for re-submitting the manuscript, and clarify the objective.
Author Response
Thank you for your valuable feedback and affirmation of our work.
