Combining Laser-Induced Breakdown Spectroscopy with the Standard Addition Method for Analyzing Impurity Elements in the Lithium Ore Mineral Spodumene

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have answered my comments in full seriousness.

I have no additional comments to the manuscriptš

Author Response

Comment. The authors have answered my comments in full seriousness. I have no additional comments to the manuscripts.

Response. We thank the reviewer for the positive feedback and for recognizing the efforts made to address the previous comments. We have made further improvements to the manuscript based on comments from other reviewers, and we hope the revised version meets your expectations.

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks for reply. I have no further questions.

Author Response

Comment. Thanks for reply. I have no further questions.

Response. We sincerely thank the reviewer for the positive assessment and support for the publication of our work. We appreciate your time and effort in reviewing our manuscript.

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript is based on LIBS combined with standard addition method to achieve rapid quantitative analysis of Be, Na, and K in spodumene, avoiding the need for sample pretreatment by traditional ICP-OES and XRF. The method is suitable for light element detection and has certain industrial application potential, but there are still shortcomings in self absorption processing and error control.

1. In the abstract, the statement “To ensure accuracy, non-resonance emissions were used for Be and Na to minimize self-absorption effects” is questionable. It is well known that Na emission lines are highly prone to self-absorption under typical plasma conditions.
2. The manuscript adopts intensity measurements from the weaker edges of spectral lines. However, it is unclear how the feasibility and accuracy of this approach were validated.
3. A schematic diagram illustrating the LIBS sample preparation process should be included. This would greatly enhance the clarity and reproducibility of the experimental methodology, especially given the importance of sample uniformity and matrix effects in LIBS analysis.
4. The manuscript does not provide details on how the detection delay time was optimized. Since delay time significantly affects the plasma emission characteristics and signal-to-noise ratio in LIBS, the authors should clarify the criteria and procedure used for selecting the optimal delay.
5. Additionally, the sample scanning speed and spatial interval between laser shots can influence both ablation uniformity and signal repeatability. The authors should discuss whether these parameters were optimized or evaluated, and to what extent they may affect the accuracy and consistency of the experimental results.
6. In Figure 3, the intensity of the K spectral line does not appear to vary significantly with concentration, in contrast to other elements that show clear sensitivity. The authors should explain this discrepancy.
7. In Figure 4, the relative error for Be spectral intensity appears significantly higher compared to that of Na and K. The authors should provide a plausible explanation for this discrepancy.
8. In Figure 8, the relative error is shown to decrease, but the RSD should also theoretically decrease under the same conditions. However, this trend is not clearly observed or discussed. The authors should clarify this apparent inconsistency and explain whether the RSD was computed independently or derived from the same data as the relative error.
9. Although the manuscript emphasizes spodumene (LiAlSi₂O₆) as a lithium-bearing mineral and highlights LIBS as a tool for lithium ore analysis, it does not provide any data or discussion on the detection or quantification of lithium itself. Given that Li is the primary element of interest in such materials, its absence significantly weakens the relevance and completeness of the study. The authors should address this gap explicitly or clarify the limitations in detecting Li using their current setup.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The submitted manuscript presents a relevant and technically competent study on the application of laser-induced breakdown spectroscopy (LIBS) combined with the standard addition method (SAM) for quantifying Be, Na, and K in spodumene. The study addresses a known challenge in light-element analysis and offers an alternative to traditional techniques like ICP-OES. However, several points require clarification, elaboration, or minor adjustments before the manuscript can be considered for publication. The following comments are provided to assist in strengthening the manuscript.

1. In the abstract, the manuscript presents LIBS as a superior alternative to both ICP-OES and XRF. However, the manuscript does not include any experimental data or direct comparison with XRF. While the stated limitations of XRF regarding light elements like Be and Na are well known, this should be either supported with specific references or removed from the abstract, as no XRF analysis is performed in the present study.
2. Have the authors considered using internal standardization (e.g., matrix element lines such as Al or Si) to compensate for shot-to-shot fluctuations or matrix effects? Justifying the absence of internal correction if not employed.
3. Although some emission lines show visibly stronger or cleaner signals, there is no quantitative discussion of SNR. Comparing SNR across resonance and non-resonance lines would help reinforce the decision to use weaker (but more reliable) lines.
4. There is no mention of whether the sample surfaces were inspected for cracks, non-uniformities, or residues after pelletization, which could introduce variability in LIBS measurements. Addressing this would strengthen the discussion of sample preparation quality.
5. The manuscript currently does not report the limits of detection (LOD) or quantification (LOQ) for the analytes. Including these values is strongly recommended for evaluating analytical performance, especially when dealing with trace-level elements such as Be.
6. The manuscript suggests LIBS as an industry-relevant tool. This could be further supported by discussing Sample throughput (total time per analysis), the robustness of the method under non-laboratory conditions, and challenges in adapting the method to field or in-line deployment.
7. Did the authors include control samples with no added analytes (blank matrix + binder) to confirm the absence of contamination or systematic background effects?

The manuscript demonstrates solid experimental work and has clear potential for publication after revision. The suggestions above are intended to help clarify and strengthen the study's technical foundation and practical impact.

Comments on the Quality of English Language

The manuscript demonstrates solid experimental work and has clear potential for publication after revision. The suggestions above are intended to help clarify and strengthen the technical foundation and practical impact of the study.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed all the comments in the revision. This manuscript is now suitable for publication.

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have responded thoroughly and thoughtfully to the reviewer’s previous comments. The revised manuscript demonstrates clear improvement in both technical clarity and presentation. The reviewer appreciates the authors’ efforts and finds the current version suitable for publication, subject only to minor editorial corrections if required by the journal.