Portable Instrument for Monitoring Environmental Toxins Using Immobilized Quantum Dots as the Sensing Material

Round 1

Reviewer 1 Report

First of all i would like to thank Authors that I have an opportunity to read such a good paper. In my opinion, the work entitled " Portable Instrument for Monitoring of Environmental Toxics using Immobilized Quantum Dots as Sensing Material", is truly innovative and well presented. The manuscript is well-written.

I have got only four minor comments:
1. Introduction: Please check the writting of bacteria species within the text. It should be wrritten in italics.
2. Can Authors calculate the average costs of this portable design, applied towards detection of toxic volatile organic compounds (VOCs)?
3. What about application of this portable instrument system in the industry?
4. Could be other types of QDs used in this system, after incroporating them inside sol-gel matrix?

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This paper describes the design and implementation of a portable sensing prototype system for the detection of acetone vapors based on the phosphorescence quenching of manganese-doped ZnS quantum dots.  The topic is certainly of interest for a large range of applications while the research work is correctly structured and quite informative as regards the design and operation of the device. On the other hand, some controls and description of experimental results underlying the involved physics are missing and require correction/integration as described below.  

1. First, the units of measurements of detection limit and concentration should be standardized throughout the text to make comparison clearer. In the Abstract a detection limit of 0.009 grams per liter of atmosphere is claimed, which translates into 0.7% by weight; in the Introduction ppm figures are used; in Results and Figure 8, percentage values are reported without specifying whether by weight or volume. In particular, it is not clear to me how the detection limit of 0.0009% in line 339 compares with 0.009 grams per liter reported in the Abstract.
2. I understand the paper was submitted to an application-oriented journal, yet I think that some sort of basic characterization of the used sensitive material should be reported; I mean a TEM or SEM image of the ZnS quantum dots should be presented;
3. In Figure 1, if the green line really is meant to describe the excitation spectrum (not the absorption one) the wavelength of the corresponding measured emission should be indicated instead of the reported wavelength range which is meaningless in that way; similar, for the emission spectrum (blue curve) the excitation wavelength should be reported;
4. A real calibration diagram/curve should be derived from data of Figure 8 and reported to show the degree of linearity of response;
5. A comparison of the obtained detection limit with similar photoluminescence-based or other portable devices should be made;
6. “dry air flux”, “humid air flux”, “hot…” and “cold…” should be reported with quantitative indications of humidity and temperature;
7. Similarly, the text between line 358 and line 366 regarding interference effects should be re-written with a more quantitative description, possibly with a graph showing the respective percentage variations; in particular lines 365-366 should be more clear;
8. In Figure 9, the author should comment on the clear drift of the signal observed after the fast decrease due to acetone vapors reaching the sensing material.

         As regards some typos:

In line 61, “molecules has have demonstrated…”    ->   “molecules have …..”

In line 115, “dots were in our…”    ->   “dots were synthesized in our …..”

In line 134, “small particles provide….but high pressure…”    there could be a missing word (?)

In line 199, “103 and 107…”    exponents misspelled?

In line 304, “curve calibration…”    ->   “calibration curve …..”

In line 323, “to increase acetone concentrations…”    ->   “to increasing acetone concentrations …..”

In line 371, “changes suffering by…”    ->   “changes undergone by …..”

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Tha authors' revisions/corrections comply to all my requests and the paper can now be accepted as is.