In Situ Detection of Trace Heavy Metal Cu in Water by Atomic Emission Spectrometry of Nebulized Discharge Plasma at Atmospheric Pressure

Round 1

Reviewer 1 Report

This basic research discusses about the emission intensity of Cu ions in the presence of atmospheric pressure plasma-AES assisted process.  The optimum experimental conditions are found and the limit of detection of copper ions are carried out. It is an interesting study and have much potential in the future cost effective elemental detection. Thus it can be accepted after a minor revision based on the following comments.

1.Pdf Page 1, Introduction: para2- ‘among them…’ sentence need clarity. ; N2 (C-B) and OH (A-X), what are C-B and A-X?.; Para 3: through comparing the …; founded? That;

2.Fig. 1: why it is called culture dish for the waste collecting dish?. Usually the culture refers to solution containing microbes.

3.Sec. 2.2.: what is the purpose/advantage of diluting CuNO3 in HNO3 ?.

4.Sec. 3.1.: …the gas that existed near the electrode…

5.Add additional images taken at different angle or positions. ; if possible add the temperature distribution image of the plasma.

6.Fig. 4 caption: check the given wavelength region.

7.Before fig. 6, the emission intensity of only Ar needs to be presented.

8.Effect of pH and signal intensity: the authors may add the reason why the Cu intensity is affected by pH similar to the reason given in the organics effect of intensity in fig. 9?.

Author Response

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Reviewer 2 Report

This manuscript proposes atmospheric pressure nebulized discharge apparatus and investigate to detect the trace metal copper by AES. The investigation is timely and of potential interest to ‘Applied Sciences’ readers. In particular, s detailed description of the experimental method is informative to the readers. In my opinion, the manuscript needs three minor revisions before publication.

1. Because of lack of my knowledge related to the detection of trace heavy metals by AES, I have a question about the metal you try to detect: Why is this manuscript trying to detect the "copper" metal among many metals? Isn't the detection of other dangerous heavy metals more important for human health and a safe work environment? Is copper representative of heavy metals in these research fields? Or is it because the sample preparation is easy and a lot of research has been done?
2. The Introduction part well explained the detailed research background. What is the difference between this study and the previous studies of other research groups? The authors need to emphasize the necessity of this experiment and the importance of this study at the end of the introduction.
3. Based on the schematics of the plasma device part (two rod-type electrode and one nebulizer) in Fig 1, the configuration of the electrode in the photograph in Fig 3 is not well understood. Provide a less magnified image so that two ends of the rod-electrodes and the end of the nebulizer can be seen (Fig. 3a), and indicate where the existing photograph (Fig. 3b) corresponds in the image.

Author Response

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Reviewer 3 Report

1- There are some grammatical mistakes. The manuscript should be improved.

2- What is the novelty of the article? 

3- I suggest to add a part (comparison with other methods) and compare the suggested method with other articles. 

4-Why the performance of the method was not investigated in the presence of other ions? 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Dear Authors, 

The manuscript has been edited properly.