High-Performance Thin-Layer Chromatography (HPTLC) Method for Identification of Meloxicam and Piroxicam
Round 1
Reviewer 1 Report
The supplier’s city and country should be mentioned in the related part of the manuscript for the reagents and the instruments.
On the other hand, the mobile phase included hexane and ethyl acetate about 9.5 mL which is far from the green technique at all when comparing methanol or acetonitrile based mobile phase in HPLC as well UHPLC. Because the piroxicam can be analyzed 40:60, ACN: Phosphate buffer about 6 minutes with the flow rate of 0.8 mL in HPLC. It means that 3.5 mL Acetonitrile consumption per analysis with the conventional HPLC. It will be better in UHPLC.
When comparing the analysis time total time for an analysis mentioned as 19 minutes include drying which is not short too.
The authors should be added a table and compare their validation characteristics with the published methods
The authors should be discussed the disadvantages of their methods besides the advantages such as the high cost of the instrument.
Another point is I could not see the application of the real sample analysis (dosage forms)
Because of the comments above, the present manuscript may not be published in this journal.
Author Response
Reviewer 1 comments:
- Reviewer 1 comment 1:
The supplier’s city and country should be mentioned in the related part of the manuscript for the reagents and the instruments.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have added the supplier’s city and country for the reagents and the instruments.
- Reviewer 1 comment 2:
On the other hand, the mobile phase included hexane and ethyl acetate about 9.5 mL which is far from the green technique at all when comparing methanol or acetonitrile based mobile phase in HPLC as well UHPLC. Because the piroxicam can be analyzed 40:60, ACN: Phosphate buffer about 6 minutes with the flow rate of 0.8 mL in HPLC. It means that 3.5 mL Acetonitrile consumption per analysis with the conventional HPLC. It will be better in UHPLC.
Authors’ response:
Dear reviewer,
Thank you for this remark. We totaly agree to you, that there are many user-friendly and “green” mobile phases in HPLC and UHPLC techniques. However, our method is HPTLC, which is based on the TLC techniques. It is true that compared to HPLC, the mobile phases for TLC have a lot of disadvantages, because most of the solvents are volatile. Because of your remark we have included paragraph about the limitations of our method.
- Reviewer 1 comment 3:
When comparing the analysis time total time for an analysis mentioned as 19 minutes include drying which is not short too.
Authors’ response:
Dear reviewer, compared to other TLC techniques the time for development is fast (it is 14 minutes). The total time for development and drying is 19 minutes.
We give some examples for TLC techniques, published in referred journals. Only the time for development is 25 or more than 25 minutes.
https://doi.org/10.1016/j.ijcas.2013.05.001 - time for development 25 minutes.
https://doi.org/10.3390/ph12040183 - time for developement 30 minues, druying 20 hours.
https://doi.org/10.1016/j.jchromb.2018.04.020 - time for saturation 30 minutes.
Thank you for your remark.
- Reviewer 1 comment 4:
The authors should be added a table and compare their validation characteristics with the published methods
Authors’ response:
Dear reviewer,
Thank you for your remark. We have included a table which compares some of the features of other TLC/HPLC methods for determination of meloxicam and piroxicam.
- Reviewer 1 comment 5:
The authors should be discussed the disadvantages of their methods besides the advantages such as the high cost of the instrument.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have reformulated the subtitle 3.4. It was “3.4. Advantages of the proposed method “, now it is “3.4. Advantages and limitations of the proposed method”.
We have also described the disadvantages of the proposed method.
“Although the proposed method has some strengths and could be easily performed, there are several limitations. Firstly, the HPTLC instrument works only with glass plates, which should be also in appropriate size (10x20 cm). Secondly, compared to TLC techniques, an additional material is required for performing the HPTLC analysis: compressed air or nitrogen are required for the sample application. In HPTLC techniques the samples are sprayed on to the plate in the form of bands or spots with semiautomatic/automatic injector, which does not work without compressed air or nitrogen. At the other hand this injector provides precise application without contact with the plates. Last but not least, HPTLC system is more expensive techniques than TLC and requires qualified person to use it. However, compared to other chromatographic techniques like HPLC and GC, the HPTLC is still much more cost-effective”
- Reviewer 1 comment 6:
Another point is I could not see the application of the real sample analysis (dosage forms).
Because of the comments above, the present manuscript may not be published in this journal.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have added a new section 3.3. Determination of meloxicam and piroxicam in Commercial Formulations.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript deals with HPTLC analysis of pharmaceutical ingredients. The authors have analyzed meloxicam and piroxicam using CAMAG HPTLC system and evaluated the detection limit and linearity of these compounds. The experiments were carried out carefully, and the results were described in detail. They have indicated that this system is useful on drug analysis. I think the data of this study is also valuable in this field, so this paper should be published in Processes with minor revision as below,
Figure 1 and Figure 2 should be combined.
Line 91-92
“CAMAG HPLC” is correct? It might be “TLC” or “HPTLC”.
Line 62-64
Please add the city and country of maker of CAMAG system.
Line 89
Why the concentration “ethanol 96%” is appropriate? Please add the explanation.
Figure 3
Please indicate the concentration of each spot.
Line 140
“fugures” is correct? It might be “figures”.
Line 159
“48ˏ64” should be “48.64”.
Author Response
Reviewer 2 comments:
This manuscript deals with HPTLC analysis of pharmaceutical ingredients. The authors have analyzed meloxicam and piroxicam using CAMAG HPTLC system and evaluated the detection limit and linearity of these compounds. The experiments were carried out carefully, and the results were described in detail. They have indicated that this system is useful on drug analysis. I think the data of this study is also valuable in this field, so this paper should be published in Processes with minor revision as below,
- Reviewer 2 comment 1:
Figure 1 and Figure 2 should be combined.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have removed the figures, because of the recommendation of the other reviewer.
- Reviewer 2 comment 2:
Line 91-92
“CAMAG HPLC” is correct? It might be “TLC” or “HPTLC”.
Authors’ response:
Dear reviewer,
Thank you for your remark. It was a spelling mistake. We have changed it to “CAMAG HPTLC”.
- Reviewer 2 comment 3:
Line 62-64
Please add the city and country of maker of CAMAG system.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have added the supplier’s city and country.
- Reviewer 2 comment 4:
Line 89
Why the concentration “ethanol 96%” is appropriate? Please add the explanation.
Authors’ response:
Dear reviewer,
Thank you for this remark. We have decided to work with “ethanol 96%” because of our previous experience.
- Reviewer 2 comment 5:
Figure 3
Please indicate the concentration of each spot.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have added the concentrations of each spot in the description of Figure 1.
- Reviewer 2 comment 6:
Line 140
“fugures” is correct? It might be “figures”.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have changed it to “figures”.
- Reviewer 2 comment 7:
Line 159
“48ˏ64” should be “48.64”.
Authors’ response:
Dear reviewer,
Thank you for your remark. We have corrected it.
Author Response File: Author Response.docx
Reviewer 3 Report
There is no novelty of the method. It reads like a student project run on a couple of HPTLC plates to establish working range and produce calibration curves.
Specific comments: Figures 1 and 2 are not necessary. Structures of meloxicam and piroxicam are well know.
Calibration curves are questionable. The slope should be close to unity, while in this case it is 0.0000237 and 0.0000335!
Author Response
Reviewer 3 comments:
There is no novelty of the method. It reads like a student project run on a couple of HPTLC plates to establish working range and produce calibration curves.
Authors’ response:
Dear reviewer,
Тhank you for your recommendations. The HPTLC methods for identification of non-steroidal anti-inflammatory drugs are limited. However, we did not find a method which could be used for identification of meloxicam and piroxicam simultaneously. Our method allows identification of meloxicam and piroxicam simultaneously and also these compounds could be identified separately. Although there is a great variety of analytical approaches for determination of drug substances, the HPTLC approach provides some benefits like simultaneous analysis of many samples, no interaction of the stationary phase with traces from previous analysis, etc.
- Reviewer 3 comment 1:
Specific comments: Figures 1 and 2 are not necessary. Structures of meloxicam and piroxicam are well know.
Authors’ response:
Dear reviewer,
Thank you for this recommendation. We have removed the figures.
- Reviewer 3 comment 2:
Calibration curves are questionable. The slope should be close to unity, while in this case it is 0.0000237 and 0.0000335!
Authors’ response:
Dear reviewer,
Thank you for this recommendation. Firstly we have built the calibration curve according to the dependence ng per band to AU. Because of this, the slope was a small number. After a short consultation with a specialist in chromatography we build another curve according to the dependence mg/ band. We have checked again the linearity and the slope. The slope for meloxicam is now 0.0231 and for piroxicam is 0.0314. All calculations were performed again.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors improved the quality of the manuscript during the revision process. It now becomes acceptable.
Reviewer 3 Report
I believe that HPTLC is more suited for EDA and bioautography.
