Cloud Point Extraction in Beverage Analysis: Innovations and Applications for Trace Elements
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsReviewer's comment on Manuscript Number: beverages-3102786
I am writing in reference to the manuscript entitled "Cloud Point Extraction in Beverage Analysis: Innovations and Applications for Inorganic Ions”. The subject of the manuscript falls within the scope of Beverages. The paper is very interesting and the results are valuable in view food analysis. The paper is generally well-written, and well planned but I have certain remarks: Remarks: xI would propose authors to make a table with advantages and disadvantages of the proposed protocol. Description of the drawbacks and advantages of Cloud Point Extraction should be listed in the first paragraph not the last one. xWhat is the recovery and precision of methods using Cloud Point Extraction? I think such information should be incorporated into table 2. xI would like to see a table listing nonionic surfactants with they drawbacks and advantages concerning their application. xThe literature should be updated. I propose to accept this paper for publication in Beverages after major amendments.Author Response
Thank you sincerely for the time and effort you dedicated to reviewing our manuscript. We greatly appreciate your valuable comments and suggestions, which will undoubtedly enhance the quality of our text.
x) I would propose authors to make a table with advantages and disadvantages of the proposed protocol. Description of the drawbacks and advantages of Cloud Point Extraction should be listed in the first paragraph not the last one.
Answer: A new table (now Table 1) has been created summarizing the advantages and disadvantages of CPE. This table has been inserted into the introduction, starting at line 87.
x) What is the recovery and precision of methods using Cloud Point Extraction? I think such information should be incorporated into table 2.
Answer: RSD and recovery values have been incorporated into both tables: originally Table 1 and Table 2, now Table 3 and Table 4, respectively.
x) I would like to see a table listing nonionic surfactants with they drawbacks and advantages concerning their application.
Answer: A new table (now Table 2) lists the most commonly used nonionic surfactants in CPE schemes. It includes key parameters such as cloud point temperature, critical micellar concentration, and density, which are crucial for selecting a suitable surfactant for CPE. The section on nonionic surfactants has been improved and can be found between lines 128 and 140.
x) The literature should be updated.
Answer: Due to the incorporation of new information and additional tables, the number of references has increased, and the literature has been updated.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe study titled "Cloud Point Extraction in Beverage Analysis: Innovations and Applications for Inorganic Ions" by Ingrid Hagarová and Martin Urík presents a comprehensive review of the application of cloud point extraction (CPE) methods for the analysis of trace elements in various beverages. The paper systematically discusses the principles of CPE, its integration with spectrometric methods, and the advancements that have enhanced its effectiveness and alignment with green chemistry principles. The study emphasizes the significant improvements in extraction efficiency and detection limits achieved by optimizing surfactants and complexing agents. Moreover, it highlights the practical applications of CPE in analyzing a wide range of beverages, such as drinking water, wine, beer, juices, tea, and milk, and the innovations that have made CPE more environmentally friendly by reducing solvent consumption and energy requirements. The authors effectively argue the advantages of CPE, particularly its ability to preconcentrate trace elements, which is crucial for detecting potentially toxic elements present at ultratrace levels. However, while the paper excels in detailing the technical aspects and benefits of CPE, it could benefit from a more critical discussion of its limitations and potential challenges in real-world applications. Additionally, the review could explore comparative analyses with alternative extraction techniques to provide a more balanced perspective. Overall, the study is a valuable contribution to the field of analytical chemistry, offering insights into the potential of CPE in ensuring food safety and public health.
Questions:
1. What are the primary limitations of cloud point extraction (CPE) when applied to complex beverage matrices, and how can these be addressed?
2. How does the performance of CPE compare to other conventional extraction techniques in terms of efficiency, cost, and environmental impact?
3. Can you provide more specific examples or case studies where CPE has been successfully implemented in real-world beverage analysis?
4. What are the potential challenges in scaling up CPE methods for industrial applications in beverage quality control?
5. How do the recent advancements in CPE align with the principles of green chemistry, and what further improvements could be made to enhance its sustainability?
Comments on the Quality of English LanguageThe English language in the manuscript is clear and well-structured, with minor grammatical errors that do not affect overall comprehension
Author Response
Thank you sincerely for the time you spent reviewing our manuscript. We particularly appreciate your questions, which prompted us to consider the broader utility of CPE procedures, especially regarding the potential challenges in scaling up CPE methods for industrial applications in beverage quality control. As my expertise is focused on the development and validation of extraction procedures at the laboratory-scale, I could only provide a theoretical response to question number 4. The content from answers 1, 2, and 5 has been incorporated into the body of the manuscript.
1. What are the primary limitations of cloud point extraction (CPE) when applied to complex beverage matrices, and how can these be addressed?
Answer: The primary limitation in this context is the complexity of beverage matrices themselves. Beverage matrices such as wine, beer, fruit juices, and milk contain a variety of components (e.g., sugars, organic acids, proteins) that can interfere with the extraction of target elements. Simple pre-treatment steps like filtration or centrifugation can help reduce matrix complexity before CPE. It is not unusual for a decomposition step to be incorporated as a pre-treatment step, even when analyzing liquid matrices. In this case, more complex organic molecules (which can contain trace elements of interest) are converted to simpler compounds, such as CO2 and H2O, and the target element is present in its simple ionic form. After that, an optimized CPE can be reliably used.
This text has been incorporated into the manuscript and can be found on lines 288-297.
2. How does the performance of CPE compare to other conventional extraction techniques in terms of efficiency, cost, and environmental impact?
Answer: Conventional extraction techniques, such as solid-phase extraction (SPE) and liquid-liquid extraction (LLE), have undergone many modifications. Nowadays, many miniaturized versions of these two extraction techniques are established and utilized with satisfactory results. Each modification offers significant advantages, but no extraction technique is without limitations. In general, CPE is known for its efficiency in concentrating analytes from various matrices, but many miniaturized versions of extractions from both templates (SPE and LLE) can also be sufficiently efficient. CPE is also generally considered cost-effective because it often requires small amounts of relatively inexpensive surfactants compared to LLE, which uses more expensive organic solvents, or SPE, which incurs higher costs due to the purchase of disposable cartridges, syringe barrels, or microcolumns. From an environmental point of view, CPE is considered more environmentally friendly compared to conventional LLE due to the use of low volumes of surfactants, which are less harmful because of their non-volatility, low toxicity, and low flammability. SPE and LLE can have a higher environmental impact due to solvent usage and disposal requirements. SPE cartridges and LLE solvent phases may contribute to waste generation and environmental contamination if not handled properly.
This text has been incorporated into the manuscript and can be found on lines 62-78.
3. Can you provide more specific examples or case studies where CPE has been successfully implemented in real-world beverage analysis?
Answer: Although the method's cost-effectiveness, environmental benefits, and adaptability to various matrices make it a promising option for broader adoption in large-scale beverage analysis, I haven't found any specific cases where CPE has been successfully used for real-world beverage analysis of trace elements (if referring to analysis in the beverage industry). However, continued advancements and optimizations in CPE techniques (mainly in the field of flow-based setups) are likely to further enhance its chances of being applied to real-world sample analysis of trace elements, even in the beverage industry. This is particularly true in laboratories where relatively less sensitive detection methods, such as UV-Vis and FAAS, are used for quantification of elements.
4. What are the potential challenges in scaling up CPE methods for industrial applications in beverage quality control?
Answer: Scaling up CPE methods from laboratory-scale to industrial applications in beverage quality control poses several challenges that need careful attention. Although the beverage industry produces enormous volumes of beverages, the analysis of homogeneous samples often requires only small sample volumes. In this context, a more important criterion in industrial applications is processing samples within a reasonable timeframe. A solution lies in designing and implementing automated systems capable of handling desirable volumes in a short time while maintaining extraction efficiency and reproducibility.
Another challenge is ensuring consistent extraction performance across different beverage matrices, especially when a laboratory analyzes various beverage samples. This critical issue can be addressed by using optimized CPE procedures tailored to the specific beverage samples since these can vary widely in composition, affecting extraction efficiency and selectivity. This means that extraction parameters such as temperature, pH, surfactant concentration, and extraction time must be suitable for each type of beverage analyzed as well as for elements monitored.
Additionally, the challenge of validating analytical methods (in this case, a method combining CPE separation/preconcentration with a suitable detection method) must be addressed. Finally, having trained staff familiar with CPE protocols is essential for successful implementation.
5. How do the recent advancements in CPE align with the principles of green chemistry, and what further improvements could be made to enhance its sustainability?
Answer: Recent advancements in CPE align well with the principles of green chemistry. These advancements focus on using very small volumes of less harmful surfactants in all CPE procedures, both conventional and innovative, which significantly reduces the use of hazardous substances and the production of hazardous waste. Another green initiative is the effort to completely eliminate organic solvents traditionally used to dissolve highly viscous surfactant-rich phases. Procedures that operate at room temperature without the need for heating systems also contribute to greener practices by reducing energy consumption.
Further improvements can involve selecting biodegradable and environmentally benign surfactants. Implementing automated CPE systems can reduce time and effort, as well as further minimize energy consumption.
In summary, a CPE procedure using biodegradable surfactants, designed for operation at room temperature in a flow-based setup, can represent a highly environmentally friendly alternative for this effective extraction technique.
Information relevant to your question (using text from this answer) can be found between lines 478 and 515."
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript concerns a quite interesting and effective method for the detection of trace inorganic components in beverages. The review is generally clear and well-managed, I suggest to pay attention to few minor points.
1) Line 72: CMC should be defined here, or a reference should be reported in the bibliography.
2) Line 79, "a surfactant": since at this moment the description of figure 1 cites a generic surfactant, it should be better that also figure 1 reports “surfactant” instead of “TX-114”. Or, as an alternative, specify in the caption of figure 1 that TX-114 is the surfactant: it is quite obvious, I know, but it makes it easier-to-read also to non-expert readers.
3) Line 85-96, "Triton X-114": for sake of clarity, specify that Triton X-114 is usually shortened as TX-114.
4) Table 1 and Table 2 should be moved after they are cited in the text, that is after line 241 and 287, respectively.
5) "Concluding Remarks and Future Perspectives": it is not section 4, it is 5.
Author Response
I would like to sincerely thank you for dedicating your time to reviewing our manuscript. Your suggestions and comments have been carefully incorporated into the text. Additionally, we have revised the figure, and I believe it is now more comprehensible.
1) Line 72: CMC should be defined here, or a reference should be reported in the bibliography.
Answer: With the incorporation of a new table and text, the abbreviation 'CMC' is first introduced and defined in line 97. Thereafter, only this abbreviation is used.
2) Line 79, "a surfactant": since at this moment the description of figure 1 cites a generic surfactant, it should be better that also figure 1 reports “surfactant” instead of “TX-114”. Or, as an alternative, specify in the caption of figure 1 that TX-114 is the surfactant: it is quite obvious, I know, but it makes it easier-to-read also to non-expert readers.
Answer: Figure 1 has been revised according to your suggestions. I agree that using 'surfactant' instead of 'TX-114' is more understandable, even for readers who are not familiar with this extraction technique.
3) Line 85-96, "Triton X-114": for sake of clarity, specify that Triton X-114 is usually shortened as TX-114.
Answer: The abbreviation for Triton X-114 has been defined in the text (now line 127).
5) "Concluding Remarks and Future Perspectives": it is not section 4, it is 5.
Answer: The subchapter 'Concluding Remarks and Future Perspectives' has been renumbered.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper has been corrected according to the remarks. It can be accepted for publication.
Reviewer 2 Report
Comments and Suggestions for AuthorsI find that the authors have addressed the feedback effectively and made significant improvements to the manuscript. Their response to each question demonstrates a clear understanding of the challenges and potential of Cloud Point Extraction (CPE) in beverage analysis. The authors have incorporated detailed explanations and relevant modifications into the manuscript, enhancing its clarity and comprehensiveness. The primary limitations of CPE when applied to complex beverage matrices were well-articulated, and the suggested pre-treatment steps such as filtration and decomposition are practical. The comparison of CPE with conventional extraction techniques is thorough, highlighting the efficiency, cost-effectiveness, and environmental benefits of CPE.
Additionally, the authors acknowledged the lack of specific real-world examples but emphasized the potential and ongoing advancements in CPE techniques, adding credibility and setting realistic expectations. The discussion on scaling up CPE for industrial applications is comprehensive, focusing on automated systems and tailored procedures for different beverage matrices. The alignment of recent CPE advancements with green chemistry principles is well-explained, with forward-thinking and practical suggestions for further improvements. Overall, the revisions have significantly enhanced the manuscript, making it a valuable contribution to the field. The authors have demonstrated diligence and responsiveness in addressing the review comments
Comments on the Quality of English LanguageThe English is clear and well-structured, with minor grammatical errors that do not affect overall comprehension.
