Simultaneous Chemical and Sensory Analysis of Domestic Cat Urine and Feces with Headspace Solid-Phase Microextraction and GC-MS-Olfactometry

Round 1

Reviewer 1 Report

Authors attempted to measure the Volatile Organic Compounds (VOCs) in the cat urine and feces to account for the malodorous nature. It is an important study to understand the effect of this foul smell on the pet owner’s health and to suggest an appropriate remediation process. The chromatograms and library matching results confirm the target VOCs. The authors also presented a detailed literature comparison in Table 1. Overall, the study design, literature survey, results, and discussion are well crafted. However, the following comments need to be addressed.

 

• How the urine and feces samples were collected? There might be potential contamination (either collection environment or collection supplies) since the target chemicals are volatiles. Did the authors perform any controlled experiment for the blank analysis?
• Considering “separations” an analytical chemistry journal, I would expect to add some quality control experiment and method optimization information in the materials section.
• Library matching factor anything over 60% is traditionally acceptable. If it is below 60%, please add a (*) and denote it as “speculative or semi-confirmative”.
• Table 2: The compound name as “?” at 17.60 RT? Either identify or remove this compound.
• Table 4 is very informative. Similarly, I suggest authors adding a sentence in the conclusion about some of the major common VOCs found in both urine and feces.
• A brief explanation or literature support would have strengthened why the VOCs were much less in the stale compare to fresh feces.
• Reported health effects (on humans) of some of the highly detected VOCs can be included in the discussion.
• Page 18, Line 293: What is s-compounds? Please expand it. Also, do the same for N-compounds.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

VOCs associated with the odors of cat urine and feces were investigated by using gas chromatography-mass spectrometry and simultaneous sensory analysis of fresh and aged samples. The article is interesting and well written. As a result of this evaluation, I suggest some changes/clarifications before advising toe publication of the article.

Please clearly define SPME-GC-MS-O first time when appear in the text

Regarding the extraction parameters, did the authors performed some optimization before using this parameters? Or did they use some previous developed method? However, please explain how you concluded that this parameters are suitable and through the best to be used for VOCs extraction (I am referring to all, extraction time, used fiber and temperature).

On the X axes of figure 1, maybe is better to put peaks/odors instead of “observations”

The Figures 2 to 4 are not essential. Maybe consider presenting them as supplementary materials.

I observed that odor description of detected VOCs is provided in the tables (both in the main text and supplementary). From where this description is taken? Do you need to mention some reference?

I will not say that is wrong, but simply unsuitable or unexpected to finish the article with a table. Please draw some conclusions or simply move some paragraphs up to not keep the Table at the end.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors made substantial improvements during the revision. The appropriate sentences were included in the discussion. Overall, the current form is very pleasing and can be considered for publication.