Preventing GC Septum Problems

Author: Mark Badger, Scott Grossman

Restek Corporation

Published By: Restek Corporation

Year of Publication: 2017

Link: http://www.restek.com/Technical-Resources/Technical-Library/General-Interest/general_GNAR2671-UNV

Abstract:

Handy tips for choosing the right septum for your application and instrument. Includes an overview of common GC septum problems, such as coring and bleed. Guidelines help you avoid extraneous peaks and optimize your system’s performance.

Influencing Selectivity in LC-MS Peptides Analysis on the Raptor ARC-18 Column

Author: Sharon Lupo, Frances Carroll

Restek Corporation

Published By: Restek Corporation

Year of Publication: 2017

Link: http://www.restek.com/Technical-Resources/Technical-Library/Pharmaceutical/pharma_PHAN2615-UNV

Abstract:

Methods for LC-MS peptide analysis often use acidified mobile phases, which can alter retention and selectivity. Here, we demonstrate the effects of modifying acid type, acid concentration, temperature, and gradient slope using several test probes. A Raptor ARC-18 column was employed for this work because the stationary phase ligand is sterically protected, making it extremely stable and resistant to acid damage at low pHs, which is an important characteristic when developing LC-MS methods for peptide analysis.

Method Development and Column Selection: How the FluoroPhenyl Phase Provides the Power of HILIC and Reversed-Phase Modes in One Column

Author: Sharon Lupo, Frances Carroll

Restek Corporation

Published By: Restek Corporation

Year of Publication: 2017

Link: http://www.restek.com/Technical-Resources/Technical-Library/General-Interest/gen_GNAR2613

Abstract:

Column selection is an important part of method development, as the quality of critical separations is determined in large part by the retention and selectivity of the analytical column. Although C18 columns are commonly employed, FluoroPhenyl columns provide an orthogonal alternative for method development because they incorporate multiple retention mechanisms and can be used in both reversed-phase (RP) and hydrophilic interaction liquid chromatography (HILIC) modes. This paper explores how FluoroPhenyl columns can be used to improve separations, especially for compounds that are difficult to analyze on a C18, such as basic analytes or small polar compounds.

Analysis of Synthetic Cannabinoids and Metabolites: Adding New Compounds to an Existing LC-MS/MS Method

Author: Sharon Lupo, Frances Carroll

Restek Corporation

Published By: Restek Corporation

Year of Publication: 2017

Link: http://www.restek.com/Technical-Resources/Technical-Library/Foods-Flavors-Fragrances/fff_FFAN2614-UNV

Abstract:

The analysis of synthetic cannabinoids and their metabolites can be a difficult and challenging task. Keeping up with the ever-growing list of synthetic cannabinoids that illicit drugmakers produce further complicates the analysis. As shown here, the retention and selectivity of the Raptor Biphenyl column allow new drugs to be added to an existing method, providing labs with an important vehicle for improving efficiency and productivity.

Rapid Analysis of C3 Epimers of 25-Hydroxyvitamin D in Serum by LC-MS/MS

Author: Shun-Hsin Liang, Frances Carroll

Restek Corporation

Published By: Restek Corporation

Year of Publication: 2017

Link: http://www.restek.com/Technical-Resources/Technical-Library/Clinical-Forensic-Toxicology/cft_CFAN2612-UNV

Abstract:

The C3 epimers of 25-hydroxyvitamin D have lower bioactivity than the primary metabolites and, unless they are chromatographically separated, can cause clinical vitamin D levels to be overestimated. Raptor FluoroPhenyl columns provide baseline resolution of all key compounds, and the method established here allows accurate quantification in a fast, 5-minute analysis time (7-minute total cycle time). This method is recommended for labs interested in reporting C3 epimer concentrations separately in order to obtain more accurate results for the clinical diagnosis of vitamin D status.

Effects of Column Inner Diameter and Packed Bed Heterogeneities on Chromatographic Performance

Author: Edward G. Franklin, Ty W. Kahler

Restek Corporation

Published By: LC-GC

Year of Publication: 2016

Link: http://www.chromatographyonline.com/effects-column-inner-diameter-and-packed-bed-heterogeneities-chromatographic-performance?topic=100,114&CID=lcgcesepsolutions.1626861.LCGC*%2520-%2520E-Separation%2520Solutions%2520%7c%2520Semi-monthly&eid=243284782&bid=1626861performance?topic=100,114&CID=lcgcesepsolutions.1626861.LCGC*%2520-%2520E-Separation%2520Solutions%2520%7c%2520Semi-monthly&eid=243284782&bid=1626861

Abstract:

In recent years industry has been moving to columns with smaller and smaller inner diameters—moving from 4.6 and 3.0 mm i.d. columns to 2.1 mm, 1.0 mm, and even smaller. While small inner diameter columns have some clear advantages, they also bring challenges.  Reduction of extra column volumes must be given greater consideration by both customers and manufacturers. This installment of “Column Watch” focuses on the sources of band broadening within high performance liquid chromatography (HPLC) columns with an emphasis on eddy dispersion. The physical mechanisms of dispersion are discussed and a review of the current literature as it pertains to small inner diameter columns is presented.

Potency Analysis of Cannabis and Derivative Products: Part 2

Author: Rebecca Stevens

Restek Corporation

Published By: Cannabis Industry Journal

Year of Publication: 2016

Link: https://www.cannabisindustryjournal.com/column/potency-analysis-of-cannabis-and-derivative-products-part-2/

Abstract:

For potency analysis via HPLC, grinding/homogenization and alcohol extraction is a common sample prep technique for dried flower and extracts.

As mentioned in Part 1, the physiological effects of cannabis are mediated by a group of structurally related organic compounds known as cannabinoids. The cannabinoids are biosynthetically produced by a growing cannabis plant and Figure 1 details the biosynthetic pathways leading to some of the most important cannabinoids in plant material.

The analytical measurement of cannabinoids is important to ensure the safety and quality of cannabis as well as its extracts and edible formulations. Total cannabinoid levels can vary significantly between different cultivars and batches, from about 5% up to 20% or more by dry weight. Information on cannabinoid profiles can be used to tailor cultivars for specific effects and allows end users to select an appropriate dose.

Appropriate Instrumentation for the Chemical Analysis of Cannabis and Derivative Products: Part 1

Author: Rebecca Stevens

Restek Corporation

Published By: Cannabis Industry Journal

Year of Publication: 2016

Link: https://www.cannabisindustryjournal.com/column/appropriate-instrumentation-for-the-chemical-analysis-of-cannabis-and-derivative-products-part-1/

Abstract:

The introduction of a series of articles focusing on the applications of instruments for different types of chemical analyses.

Election Day 2016 resulted in historic gains for state level cannabis prohibition reform. Voters in California, Maine, Massachusetts and Nevada chose to legalize adult use of Cannabis sp. and its extracts while even traditionally conservative states like Arkansas, Florida, Montana and North Dakota enacted policy allowing for medical use. More than half of the United States now allows for some form of legal cannabis use, highlighting the rapidly growing need for high quality analytical testing.

For the uninitiated, analytical instrumentation can be a confusing mix of abbreviations and hyphenation that provides little obvious information about an instrument’s capability, advantages and disadvantages. In this series of articles, my colleagues and I at Restek will break down and explain in practical terms what instruments are appropriate for a particular analysis and what to consider when choosing an instrumental technique.

Highly Reproducible Detailed cis/trans FAMEs Analysis Ensured by New Optimized Rt-2560 Column Manufacturing and Application-Specific QC Test

Author(s): Kristi Sellers and Rebecca Stevens

Restek Corporation

Published By: Restek Corporation

Year of Publication: 2016

Link: http://www.restek.com/Technical-Resources/Technical-Library/Foods-Flavors-Fragrances/fff_FFAR2589-UNV

Abstract:
Even minor variations in manufacturing processes can potentially have detrimental effects on column-to-column reproducibility. As shown here, Rt-2560 GC columns produced using a newly updated and optimized manufacturing process exhibit high reproducibility and provide consistent performance for detailed cis/trans FAMEs analysis.

Rt-2560 Columns Ensure Accurate, Reliable AOAC 996.06 and AOCS Ce 1j-07 FAMEs Analysis

Author(s): Rebecca Stevens and Kristi Sellers

Restek Corporation

Published By: Restek Corporation

Year of Publication: 2016

Link: http://www.restek.com/Technical-Resources/Technical-Library/Foods-Flavors-Fragrances/fff_FFAR2588-UNV

Abstract:
Restek has optimized the manufacturing process and implemented a new, application-specific QC testing procedure for all new Rt-2560 columns (cat.# 13198). Here we demonstrate that, Rt-2560 columns produced using the optimized process exhibit excellent performance for both AOAC 996.06 and AOCS Ce 1j-07 FAMEs analysis and meet all method requirements.