Open Probe Fast GC-MS - Real Time Analysis with Separation

Uri Keshet (1), Tal Alon (1,2) , Alexander B. Fialkov (1), and Aviv Amirav (1,2) 

1.   School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.  

2.   Aviv Analytical Ltd, 3 Haarad Street, Tel Aviv 69107, Israel  

Abstract 

An Open Probe inlet was combined with a low thermal mass (LTM) ultra fast gas chromatograph (GC) and a mass spectrometer (MS) of a standard GC-MS for obtaining real time analysis with separation. The Open Probe is based on a vaporization oven that is open to room air with an addition of helium purge flow protection that eliminates air leakage into the oven, column and MS ion source. Sample introduction into the Open Probe is as simple as; touch the sample, insert the sample holder into the open probe oven and have the results in 30 s with under a minute ready for next analysis. 

The Open Probe Fast GC-MS revolutionizes the field of real time analysis as it provides several major benefits in comparison with DART, DESI and other ambient ionization methods or MS probes:

• GC separation,
• Library identification
• Absence of ion suppression effects
• Uniform electron ionization response for improved quantitation
• Uses a low cost quadrupole MS (of GC-MS). 

Watch the short video below and keep reading to find out more about the new Open Probe fast GC-MS which was combined with Agilent 7890B GC and 5977 MS and learn about its several demonstrated application and benefits. 

If the video doesn't show, you can click here to see it on Youtube.

Approaching a Step Forward Towards the CSI Vision - Cannabis Seeds Identification with the 5975-SMB GC-MS and Cold EI

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

Ehud (Udi) Wolf (Ph.D.), head of the Analytical Lab, DIFS (division of Identification and Forensic Science), Israel police HQ, Jerusalem, Israel

Introduction 

In the popular Crime Scene Investigation (CSI) TV series (Las Vegas, New York and Miami) a common scene involves the injection of an unknown material into a GC-MS while obtaining an answer in a minute or so about what is the material. However, current GC-MS abilities are far away from such a vision, in both the time needed for analysis and particularly in the fact that GC-MS produces mass chromatograms that require data analysis. Furthermore, GC-MS data analysis generates compounds identification and not any material identification since each material is composed from many compounds and no "material library" exists. Thus, it is a major analytical and forensic chemistry challenge to advance into material identification. 

Motivated by the Israeli police request we were given Cannabis seeds with the goal of finding a new method, based on GC-MS with Cold EI, to characterize, distinguish and identify them as Cannabis seeds and not any other type of seeds. 

Initial search in the literature revealed that Cannabis seeds are claimed to have "more Omega 3 and Omega 6 fatty acids than virtually any other source, including fish" and that a highly abundant fatty acid in Cannabis seeds is the doubly unsaturated linoleic acid. In addition, Cannabis seeds are claimed to contain Vitamin E. 

We used the Aviv Analytical 5975-SMB GC-MS with Cold EI for the analysis and identification of the Cannabis seeds. Cannabis seeds appear as small, ~2-3 mm brown elongated balls, with somewhat hard shell and softer inside. Sample preparation was very simple and included crashing three seeds inside thin aluminum foil, moving the crashed seeds into a one ml glass vial with about 400 µL Dichloromethane (DCM) followed by ~3 min of sonication and injection of the DCM "extract" as is. We used such a simple form of sample preparation since the 5975-SMB GC-MS with Cold EI can uniquely elute all the sample compounds that are vaporized by the GC injector at 270ºC and enter the column, including the late eluters triglycerides. 

    

Keep reading to learn how the 5975-SMB GC-MS with Cold EI enables Cannabis seeds identification. 

Jojoba Oil Analysis using the Aviv Analytical 5975-SMB GC-MS with Cold EI

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

N. Gabriel Lemcoff, Associate Professor of Chemistry at Ben-Gurion University

Introduction 

Jojoba oil is produced from the seeds of the Jojoba plant, a shrub native to the South West USA and now also grown in the Middle East. The oil makes up approximately 50% of the Jojoba seeds by weight. Jojoba oil appears as a clear golden liquid wax and among oils it is unique because it does not contain triglycerides unlike most other vegetable oils. 

Jojoba oil is used as an additive in many cosmetic products, especially those marketed as being made from natural ingredients. In particular, such products commonly containing jojoba are lotions and moisturizers, hair shampoos and conditioners, or the pure oil itself may be used on skin or hair.

Recently Jojoba is explored as a source of bio-fuel since it has an attraction – the Jojoba plant can be grown in saline soils, and in desert lands. In fact, Jojoba is considered as one of the most practical and profitable solutions for desert plantation. Hot summers, warm winters, desert soil, minimal water, great salinity tolerance, lesser possibilities for infection, lesser need for fertilizers and generous financial income are all valuable characteristics of the plant.  

Jojoba oil has a unique composition of almost pure heavy esters with two double bonds. Professor Gabriel Lemcoff from the Ben Gurion University in Beer Sheva Israel is exploring its unique features while performing various novel organic synthesis experiments with this oil. 

Professor Lemcoff provided a pure Jojoba oil sample and asked Prof. Amirav to help with its analysis since it can not be analyzed by standard GC-MS (being too heavy and without expected molecular ions) or LC-MS.

We were able to analyze the pure oil and its chemical reaction products (which are not shown in this report) using the Aviv Analytical 5975-SMB GC-MS with Cold-EI, and in this post we present the Jojoba oil analysis results and conditions.

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.