Very Fast RP–UHPLC–PDA Method for Identification and Quantification of the Cannabinoids from Hemp Oil

Round 1

Reviewer 1 Report

This manuscript deals with the development of a robust and rapid method that can identify and quantify the most common cannabinoids found in hemp oils. The method is interesting to be considered as publication and well supported by data. However, the reviewer suggests (but it is not mandatory) to publish it as short communication (better for this kind of work).

Just two minor comments:

• Not immediately clear the “RP” meaning in the title before UHPLC. Please provide some details in the introduction and/or in the abstract.
• Please avoid abbreviations in the abstract and the suggestion is to create a list of abbreviations (with particular reference to the list of the name of cannabinoids.

Author Response

Thank you very much for your valuable comments that increase the quality of our manuscript.

Please see the attachment.

Nicoleta Blebea

Author Response File: Author Response.docx

Reviewer 2 Report

The work, entitled "Very fast RP-UHPLC-PDA method for identification and quantification of the cannabinoids from hemp oil" by Nicoleta Mirela Blebea and co. is an interesting paper on cannabinoid profile studies in cannabis samples using the chromatographic method. It is a quite good written article, the experiments are well planned, but the data are poorly presented.

There are some typos in the text (I suggest careful check all text - eg. there is Tabel - should be Table (line 193), line 216 is quantification, should be quantification, etc.) 

I've a question about Table 4 - it is very strange statement "Limit of 216 detection (LOD*) and Limit of quatification (LOQ*) determined by the calibration curves in sample units" - maybe better could be as "LOD* &LOQ* per sample (or something similar), but it is only suggestion. There is a certain inconsistency in the text. Authors use commas OR dots for decimals - it gives the impression of sloppy. 

Line 234 is 'Concentration in mg/mL was calculated by following formula" and in the equation is in [mg/g]. In my opinion, it is not necessary to enter the masses for samples 1-4 in the description of the equation (but this is the only opinion, in my opinion, this is a general equation, showing the method of calculating the content.)

Figure 2 is illegible, please add figures in better resolution.

I don't understand the data presented in table 5 (Table 5. Results for hemp oils analyzed with the proposed method and regression equations used for quantification). In Table 4 for example - Authors show LOQ in µg/mL & LOQ in mg/g for CBDV as 2.12 and 0.64 respectively. But in Table 5 there is: CBDV, sample 1&4 c [µg/mL] <2.5 and c [mg/kg <0.75. Why? Please, explain? The same situation - CBG, sample 1, etc. There is a lot of mess in the text and tables. In the case of sample 3 - I understand, that in sample 3 CBDV, CBDA (etc.) peaks are not present. But in this case - in my opinion - should be concentration as below LOQ, not N/A. 

I known, that calibration curves should be a little different (math equation) day by day, but I think, that the Authors show too many digits in this case. Table 3 and 5 are hardly legible because of this. And, in the table header (sample 4) is the capital letter Mg/g, which should be mg/g, I think.

In THCA area, sample 1 - is dot at the end - 220,806. - shouldn't there be 0 or other numbers?

There is a lack in literature section - International Conference on Harmonisation (ICH) guidelines are missed. In line 161 Authors gives [38] as ICH guidelines, but in literature, there is Thompson, M.; Ellison S.L.R.; Wood, R. Harmonized Guidelines for single-laboratory validation of method of analyses (IUPAC Technical Report). Pure Appl. Chem. 2002, 74(5), 835–855. 

Author Response

Thank you very much for your valuable comments that increase the quality of our manuscript.

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors presented a research article on a Very fast RP-UHPLC-PDA method for identification and quantification of the cannabinoids from hemp oil.

The topic is interesting and well within the aims and scopes of the Journal.

Yet, the manuscript needs some changes and implementations before it can be accepted for publication in this Journal.

The things to check and do are listed below one by one:

ABSTRACT:

- Line 21: Please modify “European space” with “European area”.

- Line 27: Please modify the relative part as follows “… with minimal sample preparation by means of high performance liquid…”.

KEYWORDS:

- Please write Cannabis sativa L. I remind the authors that Cannabis sativa must be written in Italics.

INTRODUCTION:

- “The Cannabis family comprises the Cannabis sativa and Cannabis indica species.” Cannabis is a genus. After this, according to www.theplantlist.org, Cannabis indica is now considered as a synonym of Cannabis sativa. Lastly, please write the complete botanical name of the genus and of the species sativa.

- Lines 36-38: What? There is a bad connection.

- Line 41: Please modify the relative part as follows: “… flavonoids and so on and has been used…”.

- Line 51: Erase the colon from the relative sentence.

- Lines 53-55: What? Chemical content? Not chemical structure? By the way, there is a classification of cannabinoids.

-  Lines 67-78: The use of punctuation is quite liberal here. Please uniform it and be more careful.

- Lines 78-81: What? Sentences poorly written.

- And the aim of your work is? Please add it.

MATERIALS AND METHODS:

- What about the single standards? Why use a mixture of them? You know that the behaviour of the compounds may vary if they are alone or in mixture.  

RESULTS:

- Please report a Table with the Rt of the mixture of the cannabinoids.

- In Section 3.5., I remind the authors that in English, the numbers must be written as such: 0.22 mg and not 0,22 mg. Please modify this aspect everywhere in the text and in the Tables.

- Figure 2: Not all the chromatograms are clearly visible. In addition, why that huge distortion from a horizontal line?

- Please report in Table 5 the Retention times of the compounds in the samples.

- Why did you not study more real samples?

CONCLUSIONS:

- “A high throughput of samples can be analyzed in a working day, with low costs due to solvents, energy and saved analyst time.” Yes, but you need to buy the standards if someone gives you them. What about this cost?

REFERENCES:

- In the text, multiple references should be written as follows [5,18] as requested by the Journal.

- Some references are incomplete. Missing pages or final pages.

Author Response

Thank you very much for your valuable comments that increase the quality of our manuscript.

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors presented a revised version of the manuscript I have previously reviewed.

My major concerns have been satisfactorily addressed but there are three minor ones still pending:

- Fine with the Table 1 but the correct acronym is Rt and a unity of measure would be appreciated.

- Table 4 was not modified accordingly: I remind the authors that in English, the numbers must be written as such: 0.22 mg and not 0,22 mg. Please modify this aspect everywhere in the text and in the Tables.

- References are not completely written as requested by the Journal. Erase pp from them.

When these corrections are done, the manuscript can be accepted.

Author Response

Thank you for your kind comments. We are hoping that the revised manuscript and the answers provided in this letter will clarify the reviewer concerns and the paper meets the requirements to be published.

 

Please see the attachment.

Author Response File: Author Response.docx