LIBS와 LA-ICP-MS 동시 분석을 통한 소금의 원산지 판별-[영문]

 Classification of Edible Salt Products by Tandem LA-ICP-MS and LIBS Analysis

LIBS and LA-ICP-MS have been studied and developed extensively for sample classification and discrimination technology for forensic, geological, gemological, and environmental applications.  Recent advances in LA instrumentation now makes it possible to obtain LIBS and LA-ICP-MS data simultaneously, allowing analysts to obtain more complete chemical fingerprinting information about a sample.  The blog piece below highlights the Tandem LA-ICP-MS and LIBS research work of Dr. Yonghoon Lee at Mokpo National University to apply Tandem LA-ICP-MS and LIBS analysis for discrimination of salts from different geographical origins.  More detailed technical discussion of this research was published in Spectrochim. Acta Part B 118 (2016) 102-111.

By Dr. Yonghoon Lee, Department of Chemistry, Mokpo National University, Republic of Korea

An average person is thought to consume a few to 10 g of salt per day. A wide range of edible salt products from different countries is available in local food markets. However, the price of salt products may vary significantly from cheap table salt to more expensive mineral-rich sea salts and pink/black rock salts. The large difference in salt price often encourages illegal circulation of fake salt products. Therefore, it is desirable to establish reliable fingerprints of salt products and measurement techniques to test these products.

Chemical composition can be utilized as the unique fingerprint for different types of salts. Salt is a mixture of various ionic compounds in the sodium chloride (NaCl) matrix. The concentration of magnesium (Mg), calcium (Ca), and potassium (K), ranging from several hundred ppm to a few %, depends on the production method and surrounding environment of saltpans or salt mines. These are the main metallic impurities in salts.

Commercially available salt products

Laser Induced Breakdown Spectroscopy (LIBS) is a rapid and versatile elemental analysis technique. The optical emission from the laser induced plasma conveys rich information about the chemical composition of samples. LIBS is particularly effective for the analysis of light metallic elements such as Na, K, Mg, and Ca. Thus, LIBS spectra can be chemical fingerprints of salts, indicating their geographical origins and production methods. Rich chemical information in the LIBS spectra can be effectively extracted and utilized for developing classification models involving PCA analysis.

LIBS spectra of salts from Jeung-Do (South Korea), Brazil, and Poland

Accuracy in salt classification can be improved further by combining orthogonal chemical information with respect to LIBS data. One of the elemental analyses that can be performed simultaneously with LIBS is Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). LIBS and LA-ICP-MS share the same solid sampling and sample excitation source, laser ablation.

Laser ablation chamber for tandem LA-ICP-MS and LIBS analysis

From the laser induced plasma, LIBS detects photons and LA-ICP-MS samples particles for ICP-MS. LIBS analyzes light metallic elements (K, Mg, Ca, etc.) contained in salts with relatively high concentrations (ppm to %). LA-ICP-MS can be applied for other elements in the periodic table such as non-metallic elements and heavy metals present especially at lower concentration.

The two different data from LIBS (optical emission spectra) and LA-ICP-MS (mass spectra) have been found to be independent from each other. LIBS spectra provide chemical information mainly about K, Mg, and Ca whose concentration varies by different production methods and interaction of rock salts with underground fresh water. The heavy metal LA-ICP-MS mass spectra may represent the composition contribution from the environment surrounding saltpans or salt mines. Also, iodized salt products are easily discriminated by the ¹²⁷I mass peak.

LA-ICP-MS spectra of salts from Haenam (South Korea), Hokkaido (Japan), Chile, Brazil, India, and Poland

The ideal data set for developing a classification model is prepared by combining LIBS and LA-ICP-MS spectra with optimized weighting factors.

PC score plots based LIBS, LA-ICP-MS, and their fused spectra

The evaluation of the PLS-DA model performance based on LIBS, LA-ICP-MS, and their fused data indicates that LIBS and LA-ICP-MS provide chemical information complimentary to each other. Thus, the model based on the combined data from LIBS and LA-ICP-MS led to improved classification accuracy. R&D collaboration among Mokpo National University, Lawrence Berkeley National Laboratory, and Applied Spectra revealed that tandem LA-ICP-MS and LIBS analysis is effective in capturing more complete chemical fingerprints of salts for accurate classification (Y. Lee, et al., Multivariate Classification of Edible Salts: Simultaneous Laser-Induced Breakdown Spectroscopy and Laser-Ablation Inductively Coupled Plasma Mass Spectrometry Analysis, Spectrochim. Acta Part B 118 (2016) 102-111).

Confusion matrices of PLS-DA models based on LIBS, LA-ICP-MS, and Tandem LA-ICP-MS & LIBS data

In recent years, LIBS, in combination with multivariate analysis, has proven itself as a reliable material classification technology. Classification of salts is one representative example of the expanding applications of LIBS. In the future, LIBS could be hyphenated with other spectroscopic techniques, such as LIBS-LA-ICP-MS, LIBS-Raman, LIBS-LIF, LIBS-IR, etc., for developing highly accurate material screening analytical methods.

레이저유도 플라즈마 분광법의 영어 이름

레이저유도 플라즈마 분광법은 영어로 laser-induced breakdown spectroscopy라고 쓰고 이 네 단어의 머리 글자를 따서 약자로 LIBS라고 주로 씁니다. 이 네 단어들 가운데 "breakdown"의 뜻이 모호하여 이 분광법의 속성을 그 이름으로 부터 쉽게 알기는 어렵습니다. 이 분광법의 이름을 Laser-induced breakdown spectroscopy라고 쓰기 보다는 laser-induced plasma emission spectroscopy라고 쓰는 것이 더 적합해 보이나 이미 LIBS라는 이름으로 더 널리 알려져 불리고 있습니다.

Publications

In International Journals

48.

47. H. Kim, S.-H. Nam, S.-H. Han, S. Jung, Y. Lee*, "Laser-Induced Breakdown Spectroscopy Analysis of Alloying Elements in Steel: Partial Least Squares Modeling Based on the Low-Resolution Spectra and Their 1st Derivatives", Submitted to Optics & Laser Technology. 

46. S.-H. Nam*, S.-W. Kwon, Y. Lee*, "Feasibility of Separation and quantification of inorganic arsenic species using ion exchange membranes and laser-induced breakdown spectroscopy", Analytical Letters, in press, 2018.

45. D. K. Tripathi*, A. Tripathi, Shweta, S. Singh, Y. Singh, K. Vishwakarma, G. Yadav, S. Sharma, V. K. Singh, R. K. Mishra, R. G. Upadhyay, N. K. Dubey, Y. Lee, D. K. Chauhan*, “Uptake, Accumulation and Toxicity of Silver Nanoparticle in Autotrophic Plants, and Heterotrophic Microbes: A Concentric Review”, Frontiers in Microbiology, 26 January, 2017, vol. 8, Article 7, doi: 10.3389/fmicb.2017.00007.

44. Y. Lee, J. Chirinos, J. Gonzalez, D. Oropeza, V. Zorba, X. Mao, J. Yoo, R. E. Russo,* “Laser-ablation sampling for accurate analysis of sulfur in edible salts”, Applied Spectroscopy 71, 651-658 (2017).

43. Y. Lee, S.-H. Han, S.-H. Nam, “SIMCA Modeling of Laser-Induced Plasma Emission Spectra of Edible Salts for Accurate Classification”, Applied Spectroscopy 71, 2199-2210 (2017).

42. Y. Lee,* S.-H. Nam, K.-S. Ham, J. Gonzalez, D. Oropeza, D. Quarles Jr., J. Yoo, R. E. Russo, “Multivariate classification of edible salts: Simultaneous laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass spectrometry analysis”, Spectrochimica Acta Part B 118, 102-111 (2016).

41. Y. Lee and S.-H. Han*, “Feasibility of non-destructive sugar content analysis of Korean pears by using near-infrared diffuse-reflectance spectroscopy”, Bull. Korean Chem. Soc. 37, 166-173 (2016).

40. D. Bae, S.-H. Nam,* S.-H. Han, J. Yoo, Y. Lee*, “Spreading a water droplet on the laser-patterned silicon wafer substrate for surface-enhanced Laser-Induced Breakdown Spectroscopy”, Spectrochimica Acta Part B 113, 70-78 (2015).

39. G. Park, H. Yoo, Y. Gong, S. Cui, S.-H. Nam,* K.-S. Ham, J. Yoo, S.-H. Han,* and Y. Lee,* “Feasibility of rapid classification of edible salts by a compact low-cost laser-induced breakdown spectroscopy device”, Bull. Korean Chem. Soc. 36, 189-197 (2015).

38. C. Nah,* J. Oh, B. Mensah, K.-U. Jeong, D. U. Ahn, S.-J. Kim, Y. Lee, and S.-H. Nam, “Effects of Thermal Aging on Degradation Mechanism of Flame Retardant-Filled Ethylene-Propylene-Diene Termonomer Compounds”, Journal of Applied Polymer Science, 132, 41324 (2015).

37. Y. Lee,* K.-S. Ham, S.-H. Han, J. Yoo,* and S. Jeong, “Revealing discriminating power of the elements in edible sea salts: Line-intensity correlation analysis from laser-induced plasma emission spectra”, Spectrochim. Acta Part B 101, 57-67 (2014).

36. Y. Gong, D. Choi, B.-Y. Han,* J. Yoo, S.-H. Han, and Y. Lee,* “Remote quantitative analysis of cerium through a shielding window by stand-off laser-induced breakdown spectroscopy”, Journal of Nuclear Materials 453, 8 (2014).

35. J.-W. Rhim,* L.-F. Wang, Y. Lee, and S.-I. Hong, “Preparation and characterization of bio-nanocomposite films of agar and silver nanoparticles: laser ablation method”, Carbohydrate Polymers 103, 456 (2014).

34. D. Choi, Y. Gong, S.-H. Nam, S.-H. Han,* J. Yoo, and Y. Lee,* “LIBS analysis of calcium ions in water using an ideal internal standard”, Appl. Spectrosc. 68(2), 198 (2014).

33. S. Cui, J.-S. Na, N.-Y. Kim, Y. Lee, and S,-H. Nam,* “An investigation on inorganic arsenic in a seaweed by ion chromatography coupled with inductively coupled plasma – atomic emission spectrometry”, Bull. Korean Chem. Soc. 34(11), 3206 (2013).

32. J.-T. Kim, Y. Lee, B. Kim,* D. Wang, P. L. Gould, E. E. Eyler, and W. C. Stwalley,* “Spectroscopic investigation of the A and 3 ¹S⁺ states of ³⁹K⁸⁵Rb”, J. Chem. Phys. 137, 244301 (2012).

31. Y. Lee,* S. Oh, and S.-H. Han, “Laser-induced breakdown spectroscopy of heavy metal ions at sub-ppm level in water”, Appl. Spectrosc. 66, 1385 (2012).

30. M. M. Tan, S. Cui, J. Yoo, S.-H. Han, K.-S. Ham, S.-H. Nam,* and Y. Lee,* “Feasibility of laser-induced breakdown spectroscopy for classification of sea salts”, Appl. Spectrosc. 66, 262 (2012).

29. J.-T. Kim, Y. Lee, B. Kim, D. Wang, W. C. Stwalley, P. L. Gould, and E. E. Eyler, “Spectroscopic prescription for optimal stimulated Raman transfer of ultracold heteronuclear molecules to the lowest rovibronic level”, Phys. Rev. A 84, 062511 (2011).

28. J. T. Kim,* Y. Lee, B. Kim,* D. Wang, W. C. Stwalley,* P. L. Gould, and E. E. Eyler, “Spectroscopic analysis of the coupled 1 ¹P, 2 ³S⁺ (W = 0^-, 1), and b ³P (W = 0^±, 1, 2) states of the KRb Molecule using both photoassociation and molecular beam experiments”, Phys. Chem. Chem. Phys. 13, 18755 (2011).

27. T.-K. Hwang, G.-Y. Eom, M.-S. Choi, S.-W. Jang, J.-Y. Kim, S. Lee,* Y. Lee,* and B. Kim,* “Microsolvation of lysine by water: Computational study of stabilized zwitterions”, J. Phys. Chem. A 115, 10147 (2011).

26. Y. Lee, Y. Yoon, J. T. Kim, S. Lee,* B. Kim,* “Unravelling complex spectra of a simple molecule: REMPI study of 420 nm system of KRb”, ChemPhysChem 12, 2018 (2011).

25. J. In, I. Yoon, K. Seo, J. Park, J. Choo, Y. Lee,* and B. Kim,* “Polymorph-tuned synthesis of a- and b-Bi₂O₃ nanowires and determination of their growth direction from polarized Raman single nanowire microscopy”, Chem. A Euro. J. 17, 1304 (2011), cited 23 times.

24. J. G. Son, S.-C. Choi, M.-K. Oh, H. Kang,* H. Suk, Y. Lee,* “Application of pulsed buffer gas jets for the signal enhancement of laser-induced breakdown spectroscopy”, Appl. Spectrosc. 64, 1289 (2010).

23. Y. Lee, Y. Yoon, A. Muhammad, J.-T. Kim, S. Lee, and B. Kim,* “The 480 nm system of KRb: 1 ³D₁, 4 ¹S⁺, and 5 ¹S⁺ states”, J. Phys. Chem. A 114, 7742 (2010).

22. H.-S. Kim, S.-W. Jang, S.-Y. Chung, S. Lee,* Y. Lee, B. Kim,* C. Liu, and D. Neuhauser,* “Effects of bioconjugation on the structures and electronic spectra of CdSe: Density functional theory study of CdSe-Adenine complex”, J. Phys. Chem. B 114, 471 (2010).

21. Y. Lee,* Y. Yoon, S. Lee, and B. Kim,* “500 nm system of RbCs: assignments and intensity anomalies”, J. Phys. Chem. A 113, 12187 (2009).

20. J. T. Kim, Y. Lee, and A. V. Stolyarov,* “Quasi-relativistic treatment of the low-lying KCs states”, J. Mol. Spectrosc. 256, 57 (2009).

19. T. Kang, I. Yoon, K.-S. Jeon, W. Choi, Y. Lee, K. Seo, Y. Yoo, Q.-H. Park, H. Ihee, Y. D. Suh,* and B. Kim,* “Creating well-defined hot spots for surface-enhanced Raman scattering by single-crystalline noble metal nanowire pairs”, J. Phys. Chem. C 113, 7492 (2009).

18. S.-C. Choi, M.-K. Oh, Y. Lee,* S. Nam, D.-K. Ko,* and J. Lee, “Dynamic effects of a pre-ablation spark in the orthogonal dual-pulse LIBS”, Spectrochim. Acta B 64, 427 (2009).

17. S. Im, S.-W. Jang, S. Lee,* Y. Lee, and B. Kim, “Arginine zwitterion is more stable than canonical form when solvated by a water molecule”, J. Phys. Chem. A 112, 9767 (2008).

16. Y. Lee, J. Lee, J.-S. Sohn, B.-W. Jo, and S. Han*, “Aggregation of water-soluble paclitaxel probed by excimer fluorescence of pyrenebutyric acid tag”, J. Kor. Phys. Soc. 53, 1872 (2008).

15. Y. Lee,* M.-K. Oh, S.-C. Choi, D.-K. Ko, and J. Lee, “Suppression of the methyl radical loss from acetone cation within (CH₃COCH₃)_nCH₃COCH₃⁺ clusters”, Bull. Kor. Chem. Soc. 29, 1519 (2008).

14. Y. Lee, Y. Yoon, S. Lee, J.-T. Kim, and B. Kim*, “Parallel and coupled perpendicular transitions of RbCs 640 nm system: Mass-resolved resonance enhanced two-photon ionization in a cold molecular beam”, J. Phys. Chem. A 112, 7214 (2008).

13. Y. Lee, S. Lee, and B. Kim*, “Spin-forbidden transitions in the vicinity of the 2 ¹P_u ¬ X ¹S_g⁺ band system of Rb₂”, J. Phys. Chem. A 112, 6893 (2008).

12. M.-K. Oh, Y. Lee, S.-C. Choi, D.-K. Ko, and J. Lee*, “Detection of methane and ethane by continuous-wave cavity ring-down spectroscopy near 1.67 mm”, J. Opt. Soc. Kor. 12, 1 (2008).

11. Y. Lee, S. Lee, and B. Kim*, “Mass-resolved resonance enhanced ionization study of complicated excited electronic states of Rb₂ near 430 nm and their predissociation dynamics”, J. Phys. Chem. A 111, 11750 (2007).

10. I. Yoon, K. Seo, S. Lee, Y. Lee*, and B. Kim*, “Conformational study of tyramine and its water clusters by laser spectroscopy”, J. Phys. Chem. A 111, 1800 (2007).

9. N. E. Yu*, Y. Lee, Y. L. Lee, C. Jung, D.-K. Ko, and J. Lee, “Efficient sing-pass optical parametric generation and amplification using a periodically poled stoichiometric lithium tantalite”, J. Opt. Soc. Kor. 11, 192 (2007).

8. Y. Lee, M. Schmitt, K. Kleinermanns, B. Kim*, “Observation of ultraviolet rotational band contours of the DNA base adenine: Determination of the transition moment”, J. Phys. Chem. A 110, 11819 (2006).

7. Y. Lee, J. Jung, B. Kim*, P. Butz, L. C. Snoek, R. T. Kroemer, and J. P. Simons*, “Alanyl side chain folding in phenylalanine: Conformational assignments through ultraviolet rotational band contour analysis”, J. Phys. Chem. A 108, 69 (2004).

6. Y. Lee, Y. Yoon, B. Kim*, Li Li, and S. Lee, “Observation of the 3 ³S⁺ - X ¹S⁺ transition of KRb by resonance enhanced two-photon ionization in a pulsed molecular beam: Hyperfine structures of ³⁹K⁸⁵Rb and ³⁹K⁸⁷Rb isotopomers”, J. Chem. Phys. 120, 6551 (2004).

5. Y. Yoon, Y. Lee, S. Lee, B. Kim*, “Electric quadrupole transitions of Rb₂ observed in a pulsed molecular beam: The 1 ¹D_g - X ¹S_g⁺ bands near 540 nm”, J. Chem. Phys. 116, 6660 (2002).

4. Y. Lee, C. Yun, Y. Yoon, T. Kim, and B. Kim*, “The 530 nm system of KRb observed in a pulsed molecular beam: New electric quadrupole transitions (1 ¹D - X ¹S⁺)”, J. Chem. Phys. 115, 7413 (2001).

3. Y. Yoon, Y. Lee, T. Kim, J. S. Ahn, Y. Jung, B. Kim*, and S. Lee, “High resolution resonance enhanced two photon ionization spectroscopy of RbCs in a cold molecular beam”, J. Chem. Phys. 114, 8926 (2001).

2. D. Joo, Y. Yoon, Y. Lee, S. Baek and B. Kim*, “New electric quadrupole transitions of K₂ observed in a pulsed molecular beam: The 1 ¹D_g - X ¹S_g⁺ bands near 500 nm”, J. Chem. Phys. 113, 2945 (2000) (in communication).

1. Y. Lee, Y. Yoon, S. Baek, D. Joo, J. Ryu, and B. Kim*, “Direct observation of the 2 ³P_u state of Rb₂ in a pulsed molecular beam: Rotational branch intensity anomalies in the 2 ³P_u(1_u) - X ¹S_g⁺(0_g⁺) bands”, J. Chem. Phys. 113, 2116 (2000). Cited by the book, “The Spectra and Dynamics of Diatomic Molecules”, written by H. Lefebvre-Brion and R. W. Field (Elsvier, New York, 2004).

In Domestic Journals

6. Y. Lee and S.-H. Han,* “Analysis of Magnesium, Calcium, and Potassium in Edible Salts by Using Laser-Induced Breakdown Spectroscopy”, to be published in New Physics: Sae Mulli.

5. Y. Lee, S. Jang, and S.-H. Han,* “Nondestructive sugar-content analysis for cherry tomatoes by using near-infrared diffuse transmittance spectroscopy”, New Physics: Sae Mulli 65, 508 (2015). – Highlight paper.

4. Y. Lee and S.-H. Han,* “Quantitative analysis of glucose using near-infrared spectroscopy and improvement of the measurement precision”, New Physics: Sae Mulli 64, 644 (2014).

3. Y. Lee,* D. Choi, Y. Gong, S.-H. Nam,* and C. Nah, “Laser-induced plasma emission spectra of halogens in the helium gas flow and pulsed jet”, Analytical Science & Technology, 4, 235 (2013).

2. Y. Lee,* Y.-M. Jin, and Y.-G. Cho, “Learning elemental analysis using salts”, Journal of Science Education for the Gifted, 4, 190 (2012).

1. Y. Lee and S.-H. Han,* “Feasibility study of applications of LIBS for monitoring marine environment”, New Physics: Sae Mulli 61, 976 (2011).

Patents

1.