Simultaneous Separation and Analysis of Five Compounds in Cibotium barometz by Micellar Electrokinetic Chromatography with Large-Volume Sample Stacking

Round 1

Reviewer 1 Report

In this manuscript, the Traditional Chinese medicine, Cibotium barometz, was the subject of the study. Five components present in the extract were separated by micellar electrokinetic capillary chromatography. The sensitivity was enhanced by using large volume sample stacking. The method was validated with the reference compounds, and then applied to a real plant extract. Only two substances could be quantified due to interference with the other extract components. Their recovery was determined by spiking references into the plant extract.

It is recommended to clarify, improve and correct the paper in a number of places:

Please write the name of the plant in italic throughout the paper.

Please replace micellars by micelles throughout the manuscript.

Line 97: please describe the preparation procedure of the borate-phosphate buffer more in detail: I guess it is needed to dissolve borax, then adjust the pH to 8.5 with sodium dihydrogen phosphate solution (which concentration?), and then mix this with methanol in the proper ratio?

Line 120: Figure 2 actually does not show data for reproducibility, as opposed to what is stated in the text.

Lines 211 and 214: the data for migration time are not shown.

Table 3 Line 223: R² is called a determination coefficient, instead of a correlation coefficient.

Line 228: should 130s in fact read 100s?

Please improve the English phrasing on lines 16, 17, 23, 32, 33, 39, 43, 49, 63, 71, 88, 89, 93, 95, 106, 130, 137, 140, 146, 151, 161, 166, 254, 260-261.

Please correct typing errors on lines 79, 96+202+203 (MEKC), 214.

Please pay attention to singular versus plural in English on lines 35, 48, 84, 108, 187.

Please introduce an article on lines 139, 143, 171.

Author Response

Thank you for your comments on our manuscript, please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript entitled 'Simultaneous Separation and Analysis of Five Compounds in cibotium barometz by Micellar Electrokinetic Chromatography with Large-Volume Sample Stacking' describes a method development to analyse five compounds in a medicinal plant sample by micellar electrokinetic chromatography coupled with on-line sample preconcentartion techniques.

Overall, the study is well design, executed, and presented. There are five tables and eight figures included in the manuscript.

I recommend to accept the manuscript to publishing in Separations after a minor revision.

Please find my comments and suggestions below:

1. Could you please clarify the composition of the background electrolyte? In section 3.1 a 50 mM borate buffer is described. However, the rest of the manuscript, starting from the Figure 1 captions, discusses sodium borax-sodium dihydrogen phospate buffer. What was the concentration of sodium borate and sodium dihydrogen phosphate?
2. Could you please discuss the principles of large volume sample stacking (section 3.5) before 'Optimisation of sample stacking time and injection time for LVSS (Section 3.4)?
3. Lines 147-148: 'Sample stacking allows direct analysis of unpretreated samples with complex and/or highly conductive matrices'. This statement is not accurate. Majority of the stacking techniques still requires some kind of sample preptreatment (especially when field-enhancement mechanism is involved). Perhaps the Introduction section would be a good place to discuss this matter. 
4. Would Authors agree that their work describes a dual, synergic sample on-line preconcentration approach that combines LVSS and sweeping? If the answer is yes, a change of the title could be valuable. In addition to that, a reference to the original report must be provided.   

Author Response

Thank you for your comments on our manuscript, please see the attachment.

Author Response File: Author Response.pdf