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.

Explosives Analysis with the 5975-SMB GC-MS with Cold EI

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director - Aviv Analytical Ltd, December 4, 2013.

Introduction

Effective explosives analysis is very important for homeland security and forensic applications. However, explosives analysis is challenging and the number of explosive compounds that require monitoring is growing with time. Furthermore, the growing use by terrorists of peroxide explosive compounds such TATP (triacetone triperoxide, C9H18O6) and HMTD (Hexamethylene triperoxide diamine, C6H12N2O6) implies that modern analytical techniques of explosive analysis must be as effective with peroxide explosive as with the traditional poly nitro explosives. In fact, there is no limit to the desirable LOD and selectivity of explosives analysis but these features must be combined with an analytical system that enables the analysis of the entire explosives family used by terrorists. We note that the actual system sensitivity and selectivity should be measured by its performance with the most difficult to analyze explosives such as the peroxide explosives and not with TNT and alike. 

Keep reading to find out how the Aviv Analytical 5975-SMB GC-MS with Cold EI uniquely enables the sensitive analysis of the full range of explosive compounds including TATP, HMTD, R-Salt, TNT, ETN, PETN, RDX, Tetril, HMX and Urea Nitrate while providing abundant molecular ions or high mass fragments that improve the detection selectivity and identification capability of these labile compounds.

Advanced GC-MS Presentations of Aviv Analytical in Pittcon 2013

Aviv Amirav and Tal Alon, Tel Aviv University and Aviv Analytical, Emails: amirav@tau.ac.il and polaris@tau.ac.il

In the 2013 Pittcon meeting (Philadelphia 17-21 March 2013) Prof. Aviv Amirav and Dr. Tal Alon will present six advanced GC-MS presentations performed mostly with the 5975-SMB GC-MS with Cold-EI. Brief abstracts of these presentations are given below (we will be happy to provide the full presentations upon request). 

We will be happy to meet you at our posters (240-11, 1210-6, 2180-3) or at the lecture halls after our oral presentations (1430-3, 2080-4, 2330-5) to discuss your advanced GC-MS needs and challenging applications, or any other topic.

Keep reading to find out how the Aviv Analytical 5975-SMB GC-MS with Cold EI brings the next GC-MS revolution and largely improves GC-MS performance for a broad range of applications. 

C-4 Explosives Characterization by the 5975-SMB GC-MS with Cold EI

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

Introduction 

C-4 is a widely used family of plastic explosives. It is composed of explosives, plastic binder, plasticizers and sometimes a marker taggant chemical. The explosive compound in C-4 is RDX, which makes up around 91% of C-4 by mass. The plasticizer is diethylhexyl or dioctyl sebacate and the binder is usually polyisobutylene. Another plasticizer used is dioctyl adipate (DOA). A small amount of SAE 10 non-detergent motor oil is also added. C-4 material is an off-white solid with a texture similar to modeling clay. In view of possible use of C-4 and other related type of plastic explosives (such as PE4 and Semtex) by terrorists there is an important need to have an improved method and instruments for the C-4 source identification. The various C-4 explosives can be correlated to their source in a few ways including: a) Main explosive type such as RDX with or without few percents of co-produced HMX; b) The type of taggant compound added; c) Plasticizer used; d) Oil used and its composition. However, taggant compounds are not always found, particularly in terrorist used C-4, HMX is not always found (co-produced) and while oil characterization is possible, its characterization via isomer abundance analysis although possible with Cold EI it is not sensitive enough in view of the large variety of compounds in the oil and its small concentration. Thus, we selected C-4 characterization via its plasticizers types, their isomer distributions, homologous compounds and major plasticizer related impurities. While for effective C-4 source identification one needs to build a library of C-4 explosives mass chromatograms our goal is to demonstrate the effectiveness of C-4 source characterization method via its plasticizers analysis by the 5975-SMB GC-MS with Cold EI.       

Keep reading to find out how the 5975-SMB GC-MS with Cold EI helps in C-4 source characterization for its identification via the fingerprinting of its plasticizers type, isomers and homologous compounds.

         

Pistol Oil Analysis by the Aviv Analytical 5975-SMB GC-MS with Cold EI – A New Forensic Method for the Verification of Pistol Holding

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

Introduction: 

There is an established forensic need to link between a given pistol (or any other firearm) and a suspect, who often denies ownership of that pistol, or claims that it was never touched. Pistols and other firearms are sometimes linked to their holders via their Iron print (induced by iron reaction with human sweat), which can be developed on the suspect's holding hand by special chemicals. However, there is a growing need for alternative forensic methods as some pistols or firearms have chromium coated or plastic based handles which are incompatible with the Iron print technique. In addition, the Iron print method is performed on the human suspect hand, and an alternative method based on field sample collection followed by laboratory analysis would be advantageous. 

The Novel Pistol Oil Analysis Idea: 

Every pistol and fire arm is lubricated by special oil for its improved maintenance and unhindered operation. This oil unavoidably touches the holding hand and consequently must leave its deposit on the holding hand. The oils used typically consist of a range of hydrocarbons, often aliphatic hydrocarbons that are distributed in a range of isomers. Thus, pistol oil analysis on a human hand can serve as an effective new method for linking between a given pistol and/or fire arm to the hand that held it, given that a suitable method and instrument will be found for obtaining a unique pistol oil characterization finger print.       

Keep reading how the Aviv Analytical 5975-SMB GC-MS with Cold EI enables the verification of pistol holding.

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. 

Arson Analysis by GC-MS with Cold EI – Fuel Fingerprinting by Isomer Distribution Analysis

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

Dan Muller, Ph.D., Arson Investigation Unit, Division of Identification and Forensic Science, Israel Police.

Introduction

Arson is the crime of intentionally and maliciously setting fire with the intent to cause damage. In the USA alone over 25,000 cases of arson are reported per year with estimated civilian death rate of about 300/year and property damage approaching one $Billion per year. Many arsonists use fire accelerants, such as gasoline or diesel fuel to get the fire going. However, arson analysis of the source of Gasoline, Kerosene, Diesel fuel and other accelerants represents a challenging task. We developed a new method of Isomer Distribution Analysis (IDA) and its applications for improved fuel source characterization and fingerprinting, based on the use of GC-MS with Cold EI. For more details please read A. B. Fialkov and A. Amirav "Hydrocarbons and Fuel Analysis with the Supersonic GC-MS - The Novel Concept of Isomer Abundance Analysis". J. Chromatogr. A. 1195, 127-135 (2008). 

In this Blog note we report on the use of the Aviv Analytical 5975-SMB GC-MS with Cold EI system for improved arson analysis via isomer distribution analysis of arson samples. Isomer distribution analysis is based on the fact that fuels and hydrocarbon mixtures are composed from majority of hydrocarbons and each of these hydrocarbons have many isomers that elute before the linear chain alkane, and the greater the degree of branching the earlier is the isomer elution time. Isomer distributions depend on the geographic origin of the oil that served to produce the fuel (accelerant), fuel vendor and method of fuel refining and its catalysts. Thus, isomer distribution analysis provides, as shown in this post, mass chromatograms that serves as a fuel/accelerant fingerprints to correlate them with their sources and arsonists.   

       

Five fuel samples were brought to our lab by the arson team of the Israel central police laboratory. The samples included Gasoline 2, Gasoline 3, Gasoline 4 which is Gasoline 2 after its 50% vaporization, Kerosene which was highly vaporized to be heavier than standard diesel fuel and a local diesel fuel that was contaminated with motor oil. Samples were analyzed as received with injection of 0.2 or 0.5 µL with split ratio 100 (2-5 µg total fuel on column) and analyzed with 70 eV Cold EI (EI of cold molecules in Supersonic Molecular Beams).    

Keep reading how the 5975-SMB GC-MS with Cold EI helps in arson analysis via its unique capability of isomer distribution analysis. 

Nonoxynol-9 Spermicide 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

Introduction

Nononoxynol-9, (C33H60O10, chemical structure at right) is used in a mixture with other Nonoxynol-n (Nonylphenol polyethoxilates oligomer) as a common spermicide component of condom lubricants. 

Nonoxynol-9

Condom use has been documented in sexual assault as a means by which criminals can avoid leaving behind incriminating DNA evidence. However, in the absence of DNA evidence, detection of the various components of condom lubricants can serve as a causal link between a victim and suspect. In this context, the detection of specific lubricant components such as the spermicide Nonoxynol-9 can serve as a probative link that provides an avenue to corroborate other evidence or information related to the crime. However, the detection of Nonoxynol-9 for evidentiary purposes has not been fully exploited because its physical characteristics are generally incompatible with standard GC-MS instrumentation. Recently, Shepard and co-workers (R. A. Musah, A. L. Vuong, C. Henck and J. R. E. Shepard, J. Am. Soc. Mass. Spectrom. 23, 996-999 (2012), and Pittcon 2012 poster abstract) evaluated the use of standard GC-MS for Nonoxynol-9 analysis and Prof. Shepard from the university of Albany (NY USA) kindly provided us with information on the challenge of Nonoxynol-9 analysis, and with a preprint of his paper which serves for comparison with our results. Another reference for standard GC-MS analysis of Nonoxynols (Nonylphenol polyethoxilates) is Z. Y. Wu, C. P. G. Ruhle and P. J. Marriott, J. Chromatogr. A. 1218, 4002-4008 (2011).        

Keep reading for the "small miracle" that Cold EI brings into the analysis of Nonoxynol-9. 

AM2201 Synthetic Cannabis Analysis using the 5975-SMB GC-MS with Cold EI

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

Introduction 

Synthetic cannabis is a family of psychoactive designer drugs derived of natural herbs sprayed with synthetic chemicals that, when consumed, allegedly mimic the pleasurable effects of cannabis. Synthetic cannabis is best known by the brand names such as K2 and Spice, both of which have largely become generic trademarks referring to any synthetic cannabis product. As the "herbal highs" market continues to boom, added synthetic cannabinoids are frequently exchanged to stay at least one step ahead of legal restrictions. 

AM2201 (1-(5-fluoropentyl)-3-(1-naphthoyl)indole) C24H22FNO (MW=359.17, structure at right) is a synthetic cannabis compound that acts as a potent agonist for the cannabinoid receptors CB1 and CB2. Its binding affinity to the CB receptors (activity) is about 15-40 times greater than of tetrahydrocababinol (THC) itself, which is the main natural active ingredient found in cannabis. 

The analysis of synthetic cannabis such as AM2201 is relatively simple and can be performed with any standard GC-MS. However, it requires sample preparation which often takes more time than is generally available in busy forensic laboratories. Thus, the main challenge in synthetic cannabis analysis is how to perform it with minimal sample preparation and chromatography time.

In this post we show the fast sample preparation of herb leaves for the analysis of AM2201 using the 5975-SMB GC-MS.

Tetryl Analysis using the 5975-SMB GC-MS with Cold EI

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

Introduction

Tetryl, (2,4,6-Trinitrophenylmethylnitramine, C7H5N5O8) is a sensitive explosive compound used to make detonators and explosive booster charges. Tetryl is produced by slowly mixing dimethylaniline with concentrated nitric acid in the presence of sulfuric acid and due to its simple synthesis it is prone for attempted synthesis by terrorists. Tetryl is a thermally labile explosives that is known to be difficult to analyze by GC-MS due to its degradation at the GC injector and at the GC column to N-methylpicramide through a loss of NO and a gain of hydrogen from the column PDMS film. As a result, the analysis of Tetryl is challenging. 

   

We received a sample of Tetryl that was synthesized by A.I. Explosives, Inspection & Services Company (www.aiexplosives.com) that attempted to follow terrorist's synthetic roots and characterize it via the tetryl synthetic impurities.   

In this post we present the uniquely successful analysis of Tetryl perform with Aviv Analytical's 5975-SMB GC-MS.    

Very Fast Heroin Analysis – The Role of Flow Programming

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

Introduction 

Forensic laboratories are often confronted with a need to analyze hundreds of "white powders" for the presence of drugs of abuse or otherwise to determine their harmless nature. However, a typical "fast" analysis utilizing a standard GC-MS can take 20 minutes (full analysis cycle time including chromatography and cooling back for the initiation of next analysis). Thus, there is a growing need for improved instruments and methods that are capable of much faster analysis cycle times, while retaining good separation and high quality mass spectra for identification purposes.    

Heroin, like many other drugs of abuse, is sold in the streets as a powder mixture which typically contains paracetamol (also named acetaminophen) and caffeine as its major ingredients and a few percents each of 6-monoacetylmorphine (coeluting with some acetylcodeine), heroin, papaverine and noscapine in order of their GC elution times. Thus, a fast street heroin analysis must preserve the proper separation of all its major ingredients while providing full separation of the heroin itself for its quantitation and eluting the last to elute noscapine and anything else that might otherwise contaminate the column. 

In this post we present the details of our rapid analysis of heroin.