The Discovery of New Ant Head Compounds via ChromatoProbe Sampling and 5975-SMB GC-MS with Cold EI

Aviv Amirav (1), Raya Seltzer (2), and Abraham Hefetz (3), 

1. Professor of Chemistry at Tel Aviv University and Director – Aviv Analytical 

2. Graduate student at the department of Zoology at Tel Aviv University 

3. Professor of Zoology at Tel Aviv University   

Introduction

Ants represent an interesting example of social insects and thus the chemical composition of their epicuticle is widely explored including in order to learn about the way they communicate. Much of the chemical ecology research of ants is focused on their wax hydrocarbons structure. In a previous post we described the results of our study of Ants Communication Exploration via their Wax Analysis by GC-MS with Cold EI – The Unique Role of Hydrocarbon Isomer Distributions.

As often the case, when new and powerful equipment is being used new discovery are being found as described in this post. We followed our exploration of the chemical structure of Cataglyphis ant waxes with the Aviv Analytical 5975-SMB GC-MS with Cold EI via sampling with the CPAV7980 ChromatoProbe sample introduction device. The ChromatoProbe allowed us to introduced ants body parts and glands without any sample preparation for their intra injector thermal extraction combined with GC-MS with Cold EI analysis with its features of having significantly enhanced molecular ion abundances, amplified isomer structural mass spectral effects and the ability to have tail free GC-MS analysis of underivatized free fatty acids. 

Keep reading how the 5975-SMB GC-MS with Cold EI in combination with the CPAV7890 ChromatoProbe brings new, untapped and important chemical information about ants wax composition.       

Ants Communication Exploration via their Wax Analysis by GC-MS with Cold EI – The Unique Role of Hydrocarbon Isomer Distributions

Aviv Amirav (1), Raya Seltzer (2), and Abraham Hefetz (3), 
1. Professor of Chemistry at Tel Aviv University and Director – Aviv Analytical 
2. Graduate student at the department of Zoology at Tel Aviv University 
3. Professor of Zoology at Tel Aviv University

Introduction 

Ants are social insects and thus the exploration of their ways of communication is an interesting research area. For example, nestmate recognition is essential for ants for the defense against exploitation of nest resources, and such recognition is largely mediated by chemical signals. When two individuals meet they match the label, the chemical signal it carries on the epicuticle and represents the colony odor, with a postulated neural template present in the brain. If the label matches the template amicable interactions between the individual ensue, (photo in the graphical abstract) otherwise they engage in aggressive interaction. Since the ant wax is composed mostly from saturated hydrocarbons, both linear chain and their branched isomers, we decided to explore the chemical structure of ant waxes with the Aviv Analytical 5975-SMB GC-MS with Cold EI which significantly enhances the molecular ion abundances and amplifies isomer structural mass spectral effects. We studies Cataglyphis ants from 17 different nests in various locations in Israel and found that although morphologically they are practically indistinguishable, isomer distribution analysis found significant differences between cryptic ant species or ants from different nests. Thus, the data strongly supports the hypothesis that ant communication is based on branched hydrocarbon abundances as a recognition fingerprint. 

Keep reading how the 5975-SMB GC-MS with Cold EI helps in ant communication research and to view the important role of isomer distribution analysis in our findings.  
    

Flies Wax Analysis by GC-MS with Cold EI and its Comparison with Standard EI

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director – Aviv Analytical, 

Joanne Yew, Temasek Life Sciences Laboratory and National University of Singapore, Department of Biological Sciences, Singapore. 

Introduction 

Insects such as flies, ants and mosquitoes express species-specific blends of cuticular hydrocarbons (CHCs) on their surface that serve as pheromones and play an important role in their behavior and communication. In view of growing interest and importance of this research area recently several advanced tools were developed for improved CHCs analysis. However, one major limitation of these methods and instrumentations is that alkanes cannot be properly detected via some of the atmospheric pressure ionization ion sources while in standard electron ionization as used with GC-MS the molecular ion is often very weak or altogether missing thereby proper identification is hindered. Furthermore, standard GC-MS is limited to relatively small compounds up to about C40-C44. Thus, we explored the chemical structure of fly and mosquito waxes with the Aviv Analytical 5975-SMB GC-MS with Cold EI which significantly enhances the molecular ion abundances, amplifies and exposes isomer structural mass spectral effects and enables the elution of much larger hydrocarbons via the use of short columns with high column flow rates. In addition, it provides uniform response for accurate quantification of the waxes compounds which is superior to standard EI and in contrast to API ionization methods (APCI, DART MALDI etc). For further information on GC-MS with Cold EI please read the review article A. Amirav, A. Gordin, M. Poliak, T. Alon and A. B. Fialkov "Gas Chromatography Mass Spectrometry with Supersonic Molecular Beams" J. Mass. Spectrom. 43, 141-163 (2008)., which is available on request. In this post we report on the analysis of two fly samples. A) Male Drosophila melanogaster, and B) Male Drosophila mojavensis. 

Keep reading how the 5975-SMB GC-MS with Cold EI drastically improves flies cuticular hydrocarbons analysis and bring novel tools for its characterization. 

               

Beeswax in Fruit and Vegetables Analysis and the Emerging Challenge of Material Identification

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director – Aviv Analytical 

Igal Bar Ilan Ph.D.  Migal Laboratories, Kiryat Shmona Israel    

Introduction 

Beeswax serves to treat growing numbers of fruits and vegetables in order to increase its shelf time, reduce product dehydration, suppress mold growth and improve the appearance (shiny) of the treated fruits or vegetables. However, while wax is generally considered as safe, some say that such treatment serves as an evidence for extended (long) time between harvest and consumption hence reduction in certain nutrients. A few types of waxes are used but beeswax is considered as an "organic" wax hence of high quality. Recently beeswax analysis is required in certain fruits and vegetables (by the EU) and standard GC-MS or LC-MS failed to perform such challenging analysis. Beeswax is used in combination with minor addition of olive oil and the challenge is to develop a method to analyze such wax in the 1-100 ppm range in certain fruits and vegetables. Note that wax is a mixture of several heavy compounds, most notably hydrocarbons and heavy esters plus some triglycerides, thus 1 ppm means about 40 ppb each of its major heavy ingredients. In addition, unlike in pesticide analysis in this case the emerging challenging need is to identify a material as opposed to compound. 

After method development we successfully analyzed the wax in 16 fruit and vegetable samples including avocado, cucumber, tomato and apple using the Aviv Analytical 5975-SMB GC-MS with Cold-EI.

Keep reading for the analysis details, results and conclusions.