Oiling up: LIBS spots the Swan

Skip to Navigation

Ezine

  • Published: Dec 15, 2013
  • Author: David Bradley
  • Channels: Atomic
thumbnail image: Oiling up: LIBS spots the Swan

Single parameter character

Classification of vegetable oils based on their concentration of saturated fatty acids using laser induced breakdown spectroscopy (LIBS)

Laser-induced breakdown spectroscopy, a powerful atomic emission spectroscopic, technique has been used to analyse organic liquid media, such as vegetable oils and sweetened water. The demonstration that LIBS can highlight the "Swan band" of C2 emitted by different vegetable oils could allow this technique to be used to characterize oils by a single parameter for the determination of saturated fatty acid concentration in this important cooking ingredient.

Yvon Mbesse Kongbonga, Hassen Ghalila and Zohra Ben Lakhdar of the Laboratory of Spectroscopy of Atomic Molecular and Applications – LSAMA, at the University of Tunis, Tunis, Tunisia, working with Marthe Boyomo Onana of the Centre for Atomic Molecular Physics and Quantum Optics – CEPAMOQ, at the University of Douala, Douala, Cameroon, explain the benefits of LIBS in the journal Food Chemistry. The technique has applications in industry, archaeology, geology, environmental science and the field of biomedicine because of its relative simplicity, speed of analysis, ability to be used with a wide range of analytes and materials and the quasi non-destructive nature of the method.

It's all in the plasma

The researchers point out how LIBS has grown in popularity over the last ten years or so, but it is still most commonly used to analyse the mineral content of samples, the calcium, magnesium, phosphorus, potassium and sodium concentrations, for instance, used as a proxy marker for the presence of specific organic compounds. It has thus been used rather successfully to characterise biological media in conjunction with other techniques.

Other research groups have also demonstrated that LIBS can home in on the presence of specific elemental groupings in samples containing organic substances, such as Cand CN. Unfortunately, it seems that the presence of vibrational bands due to CN arises through a combination of organic carbon with ambient nitrogen and so does not necessarily reflect the presence of an organic nitrogen compound in the target sample. By contrast, the Cgroup might arise from the ejection from the plasma of pulverised molecular fragments, the team adds.

Linearity

Much effort has been focused on the C2 grouping to prove its origins in LIBS data. Now, Kongbonga and colleagues have investigated the so-called Swan band due to Cemitted by different vegetable oils in the liquid phase. They hope that their focus will not only allow them to characterise this important food stuff, and of course, latterly biofuel feedstock, in order to determine, the characteristics of each of these organic media. Moreover, their study points to the possibility of a single parameter that might be used to characterise different vegetable oil products based on their saturated fatty acid content, for regulatory, research and fuel supply research and production.

The LIBS study showed that the control sample, sweetened water containing saccharose (cyclic), does not give rise to the CSwan band. In contrast, the presence of linear chain fatty acids in the numerous vegetable oils tested most certainly show a Cemission in plasma. "The present work suggests that the Cemission depends on the form of the molecule constituting the pulverized sample to create plasma," the team says. "It seems that there is emission of C2 if the molecule contains at least one linear carbon–carbon bond, the researchers add."It was also shown that oil containing more saturated fatty acids emit more Cbut shows no correlation with the number of double bounds." The team's statistical analysis has allowed them to design the much-desired single parameter for classifying vegetable oils of given saturated fatty acid content.

"This is a first step," Mbesse told SpectroscopyNOW. "We intend to continue the analysis particularly of organic liquid media with LIBS in order to understand the dynamics of molecules created in the plasma, that will lead to numerous applications."

Related Links

Food Chem, 2014, 147, 327-331: "Classification of vegetable oils based on their concentration of saturated fatty acids using laser induced breakdown spectroscopy (LIBS)"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

Social Links

Share This Links

Bookmark and Share

Microsites

Suppliers Selection
Societies Selection

Banner Ad

Click here to see
all job opportunities

Most Viewed

Copyright Information

Interested in separation science? Visit our sister site separationsNOW.com

Copyright © 2017 John Wiley & Sons, Inc. All Rights Reserved