Release of Selected Non-Intentionally Added Substances (NIAS) from PET Food Contact Materials: A New Online SPE-UHPLC-MS/MS Multiresidue Method

Round 1

Reviewer 1 Report

The manuscript presents the study on releasing of non-intentionally added substances (NIAS) from PET food contact materials. In this study the selected food contaminants were analyzed by SPE-LCMS method in multiple ion monitoring mode. Nowadays, due to the ubiquity of plastic packaging, the control of contaminants from and infiltrating food is highly desirable, including the development of appropriate control methods. The work was carried out methodologically correctly and quite logically presented. Therefore, according to my opinion, after fixing some shortcomings and clarifying the issues presented below, I will recommend the article for publication.

1) line 153 "Chromatographic and online SPE flows were 0.3 and 0.5 mL/min). I suggest to use the term "flow rates"

2) The authors wrote that they set up some quadrupole parameters required for proper MRM analysis, but there is no indication in the manuscript, if the parameters were chosed manually or by automatic optimization

3) Table 1 column 3 contains the set of fragmentation ions which were then used in MRM mode, but my concern is the number of ion transitions used for MRM analysis. If I understood correctly, one MRM transition was used during the analysis. Actually, two MRM transitions are the gold standard, so I dont understand why the authors only used one.

4) Figure 1. The y axis should contain an unit. Moreover, the numerical values of the transitions are inconsistent, one has a unit value, the other contains a decimal value

5) line 144. Please explain the use of eluent B with the content of 80%ACN and 20% of MeOH. This is a rather rarely used combination.

6)It is required to standardize the formatting of the bibliography. Some citations contain DOI number and others do not. One literature reference has quotation marks in the title of the article, the other does not.

 

Author Response

Please kindly see the attachment. Many thanks!

Author Response File: Author Response.pdf

Reviewer 2 Report

Line 106. Why it is necessary for pre-concentration?

Line 198. may need a reference.

Line 208. the SPE protocol is a manual operation or automatic?

Line 223. 'NIAS we' to 'NIAS, we'

Line 107. please be specific and provide more details/ equations for the estimation and calculation of 'limit of detection (LOD), of quantitation (LOQ), lower LOQ 108 with RSD% and BIAS%'

Line 234. please list the 'limits suggested by FDA' with reference, here.

Line 335. please provide a picture of the 'Online SPE as automated extraction procedure' marked with each component in the supplementary.

Author Response

Please kindly see the attachment. Many thanks!

Author Response File: Author Response.pdf