Pittcon 2019
Conference & Expo

Pittcon
Restek at Pittcon 2019

ORAL SESSIONS

Analysis of Acylglycerols in Olive Oil by Gas Chromatography
Colton Myers (presenter)
Restek Corporation
For more information, email Colton Myers.
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The analysis of olive oil is essential to the food industry due to the amount of fraudulent activity that surrounds this product. Some olive oils (e.g., extra virgin olive oil) carry high value, therefore making it an easy target by frauds. By mixing different vegetable oils (e.g., rapeseed, sunflower, etc.) with high quality olive oils, manufactures increase their oil yields and make larger profits on these counterfeit olive oils. Using gas chromatography (GC), these extraneous vegetable oils are able to be detected by looking at the triacylglycerol (TAG) fingerprint for a given olive oil. In addition, the freshness of the olive oil can be determined by looking at the ratio of 1,2- to 1,3-diacylglycerols (DAG). In this study, different commercially available olive oils were purchased and tested for authenticity and adulteration. The analysis and results for these oils will be presented.

Application: Food Science
Methodology: Gas Chromatography

Gas Chromatographic Computer Modeling Software for Optimized Method Development
Jaap de Zeeuw (presenter)
Restek Corporation
For more information, email Jaap de Zeeuw.
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Our recently introduced modeling software is a selectivity tool that relies on a preloaded library of thermodynamic retention indices. This makes it possible to predict retention times and optimize chromatographic methods without the need to analyze compound sets under many different conditions. The program allows the user to select the stationary phase and simultaneously adjust film thickness, temperature, column length, column internal diameter, and flow. Users can enter each compound or cut/paste large lists of compounds into the program.

Since its introduction there have been thousands of searches across a broad range of compound classes. The program outputs compound retention time, resolution, and peak width along with the column conditions and dimensions. A model chromatogram is provided to illustrate retention, peak width, and resolution. Users have the option to view compound mass spectral data with the added benefit of overlaying mass spectra for coeluting analytes. Specific searches can be saved and accessed at a later date. Examples of these features will be presented with a focus on challenging separations.

Application: High-Throughput Chemical Analysis
Methodology: Gas Chromatography

Faster GC-MS Analysis with Short Narrow Bore Column and Method Translations
Jaap de Zeeuw (presenter)
Restek Corporation
For more information, email Jaap de Zeeuw.
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Designed with GC-MS users in mind, the GC Accelerator kit provides a simple way to speed up sample analysis. By reducing oven volume, these inserts allow faster ramp rates to be attained, which reduces oven cycle time and allows for increased sample throughput and more capacity to process rush samples. When faster ramp rates are used, existing methods can be accurately scaled down to smaller, high-efficiency, narrow-bore columns using the EZGC method translator. With a scaled-down column, a properly translated method, and a GC Accelerator kit, you can obtain the same chromatographic separation—often with greater sensitivity—in a fraction of the time without making a capital investment.

Application: Environmental
Methodology: Gas Chromatography/Mass Spectrometry

WORKSHOP

A Hybrid HILIC and Anion-Exchange HPLC Column for Separation of Polar Compounds
Xiaoning Lu (presenter)
Restek Corporation
For more information, email Xiaoning Lu.
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Hydrophilic interaction chromatography (HILIC) columns have been gaining more and more interest due to their ability in the retention and separation of polar compounds, such as amino acids and carbohydrates. Additionally, a HILIC separation, operated with high organic content, offers excellent compatibility with MS detection. Various HILIC phase chemistries, including base silica, polyols, amino, zwitterions, and mixed phases, have been reported. However, the separations of highly polar anions, such as glyphosate and its metabolites, by a HILIC column remain difficult. On the other hand, an anion-exchange column has been an important means to separate anionic compounds like organic acids. However, many of the anion-exchange separations are not compatible with MS detection due the use of nonvolatile salts.

The presentation describes the development of a hybrid HILIC and Anion-Exchange HPLC column. Under HILIC or MS-compatible conditions, the hybrid column has been demonstrated not only useful for the separation of polar anions, including glyphosate and its metabolites, organic acids, and water-soluble vitamins, but also applicable for neutral and positive analytes such as amino acids, carbohydrates, and peptides. In addition, the column employing superficially porous particles offers higher speed and efficient separations than the columns with full porous particle of similar size.

Application: General Interest
Methodology: Liquid Chromatography

RESTEK TECHNICAL POSTERS

How Clean Are My Shut-Off Valves?
Linx Waclaski (presenter)
Restek Corporation
For more information, email Linx Waclaski.
Download a PDF of the full presentation.
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Shut-off valves provide a convenient means to manipulate gas flows and are often used in conjunction with gas chromatography systems. The ability to control gas flows at the instrument is useful for several maintenance tasks. A number of different types of shut-off valves are available, including ball valves, plug valves, and sealed diaphragm valves. In order to allow for easy opening and closing of the valves, as well as reduce wear on moving parts, some valves, such as ball and plug valves, use a silicone-based lubricant. Unfortunately, this lubricant can potentially off-gas into the flow path, leading to instrument contamination and baseline interferences.

This study qualitatively examines the degree of contamination off-gassing from various types of shut-off valves when attached directly behind a gas chromatograph. A high flow of carrier gas was passed through each valve, while leaving the GC oven at a low temperature to trap contamination on the column. A temperature ramp was then performed to evaluate the trapped components. This experiment was repeated by placing a gas filter containing a hydrocarbon trap after each valve in order to evaluate the effectiveness of a filter in removing contamination.

The Effect of Liner Geometry on Split and Splitless GC Analyses of Liquid Extracts
Linx Waclaski (presenter)
Restek Corporation
For more information, email Linx Waclaski.
Download a PDF of the full presentation.
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Split and splitless injections are two of the most commonly used modes of introducing samples to a gas chromatograph. Most split and splitless injectors for capillary columns utilize a replaceable glass inlet liner where the sample is initially vaporized and transferred to the column. It is important that the introduction of analytes into the system is both representative of the sample and reproducible. The shape of a liner, as well as the presence of glass wool or another geometric feature, can have a large impact on accuracy and precision.

This study evaluates a variety of liner designs for use in split and splitless injections. A test mix containing aliphatic hydrocarbons ranging from C8 up to C40 is used to evaluate the different liner designs for analyte response across the entire range, as well as reproducibility for multiple injections. The potential impact of liner shape on inertness is also briefly explored.

Complete Fractionation of Extractable Petroleum Hydrocarbons Using Newly Developed Small Bed EPH SPE Cartridges
Alexandria Pavkovich (presenter)
Restek Corporation
For more information, email Alexandria Pavkovich.
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Due to its prominent use in the modern era, petroleum, in one form or another, is an ever-present commodity that surrounds us in our daily lives. From its primary use as a fuel in transportation, to its role as an essential feedstock for industry, or as an energy source for home heating, petroleum's widespread use leads to instances of uncontrolled releases to the environment.

When an assessment of the affected soil or waters from a spill needs to be made, an effective and comprehensive analytical method should be available in order to make an appropriate decision about the nature of remediation required to ameliorate the situation and mitigate the hazardous nature of the contaminated areas. This is where the Massachusetts Department of Environmental Protection made a valuable contribution through their Method for Determination of Extractable Petroleum Hydrocarbons (EPH). Recognizing the utility of this method, other states followed the lead, such as New Jersey and Texas, and adopted their own versions based largely upon this work.

The ability to successfully execute such a method requires an SPE cartridge that can discern between two major classes of compounds and depends entirely upon the cartridge's ability to cleanly fractionate the sample extract for subsequent GC analysis. Also critical in ensuring integrity in the analysis is the capability to provide a background free of interferences. The ability to effectively fractionate the sample is an intrinsic attribute of the silica combined with the moisture level of the finished cartridge, while the background is tied to the cleanliness and lack of leachable materials in the silica and the surfaces of the cartridge components.

This work explores the capabilities of a newly released product in the use of the aforementioned analytical methods.

Application: Environmental
Methodology: Sampling and Sample Preparation

A Simple Approach to Analyzing Residual Solvents in Cannabis Concentrates via HS-GC
Colton Myers (presenter)
Restek Corporation
For more information, email Colton Myers.
Download a PDF of the full presentation.
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With more states legalizing medical and recreational use of cannabis, there is a need for analytical methodologies to ensure consumers receive safe products. Currently, there is a growing trend in cannabis concentrates. These concentrates are created by extracting the chemical compounds, such as Delta-9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD), from the cannabis plant. Manufacturers use a variety of extraction solvents in their processes. This study focused on analyzing residual solvents in cannabis concentrates with a like-USP <467> sample preparation technique. Subsequently, residual solvents were extracted with the more "classical" approach of HS-syringe and then compared to extractions with a large volume HS-SPME approach (i.e., SPME Arrow). Comparison results and a simple solution for analyzing these complex matrices will be presented.

Application: Biomedical
Methodology: Gas Chromatography

Analysis of Trans-Fatty Acids in Food Products Using Various GC Columns
Jana Rousova (presenter)
Restek Corporation
For more information, email Jana Rousova.
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Partially hydrogenated oils, which are the main source of artificial trans-fatty acids (TFAs), have been phased out in Europe and the United States due to concerns of their negative effect on human health. Unfortunately, artificial TFAs remain present in the food industry of the rest of the world. Moreover, certain food products have been exempted from the ban, such as frosting. In order to analyze the presence of TFA in U.S. food products, we evaluated several fat-containing products: margarine, shortening, butter-flavored popcorn, and chocolate frosting. The fatty acids were trans-esterified using sodium methoxide and analyzed on multiple Restek columns, namely Rtx-2330, Rt-2560, and FAMEWAX using GC-FID and GC-MS. With the exception of frosting, none of the studied products contained TFAs. However, there was a tradeoff. The elimination of partially hydrogenated oils led to significant increase of saturated acid content in margarine and shortening as compared to previously reported values by USDA. In terms of column selection, the Rt-2560 was the best choice for the separation of C18:1 isomers extracted from chocolate frosting.

Application: Food Safety
Methodology: Gas Chromatography

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