Diagnosing and Preventing High Back Pressure in LC Systems

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/General-Interest/general_GNSS2880-UNV

Abstract: 

High backpressure is one of the most common problems encountered in LC systems. Here, we review the typical causes, give tips on troubleshooting, and provide details on routine maintenance parts and practices that can help you avoid unplanned instrument downtime.

Reliable Low-Level Analysis of Glycols in Water Using Split Injection

Author: Corby Hilliard and Chris English

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/Environmental/enviro_EVAN2873-UNV

Abstract: 

Obtaining consistent results for low-level analysis of glycols in water samples is difficult when using splitless injection due primarily to issues with backflash, poor peak shape, and shifting retention times. The split injection method shown here avoids these problems and reliably produces good chromatographic results. Lifetime testing demonstrated that Rtx-Wax columns produce stable results, even after column integrity was challenged with 600 water injections.

Accurate Analysis of Glycerol and Glycerides in Biodiesel Oil Using EN 14105 (2011) and Robust Metal MXT Columns

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/Petroleum-Petrochemical/petro_PCAR2872-UNV

Abstract: The high temperatures required to analyze glycerol and glyceride contaminants in biodiesel can result in short column lifetimes and more downtime for maintenance. Metal MXT-Biodiesel TG columns are more durable and longer lasting than their fused silica column counterparts, making them a better choice for labs wanting to minimize downtime. As demonstrated here, MXT-Biodiesel columns meet method EN 14105 (2011) performance requirements and provide excellent chromatographic results for biodiesel testing.

 

Using Method Detection Limits to Set Mandatory Reporting Limits for Banned Pesticides: How a Public-Private Partnership Improved Cannabis Regulation in Colorado

Author(s): Joseph Konschnik1, Heather Krug2, Shawn Kassner3
1. Restek Corporation, 2. Colorado Department of Public Health & Environment (CDPHE), 3. Neptune and Company, Inc.

Published By: Cannabis Science and Technology

Issue: 1

Year of Publication: 2018

Link: www.cannabissciencetech.com/pesticides/using-method-detection-limits-set-mandatory-reporting-limits-banned-pesticides-how-public-private

Abstract: The discovery of nonregistered pesticides contamination in cannabis plant material in Colorado prompted the need to set mandatory reporting limits (MRLs) for these pesticides in the state to ensure public safety. Since then, the Colorado Department of Public Health and Environment (CDPHE) undertook the responsibility for setting such MRLs. Colorado’s novel approach to determine MRLs for each pesticide involved forming a working group with its in-state laboratories and expert volunteers to agree on analytical procedures to determine method detection limits (MDLs) using an industry-standard approach. The authors describe how this approach formed a collaborative public-private partnership where state government agencies worked side by side with laboratories and growers toward a common goal. The multilaboratory study was completed yielding MDLs for 13 pesticides in cannabis flowers using a QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction with analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The authors share the procedures used for the study, an overview of the data generated by the participating laboratories, and the new Colorado MRLs, which became effective on January 1, 2018.

High-Throughput Analysis of Cannabinoids by LC-UV

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/Foods-Flavors-Fragrances/fs_FFSS2851-UNV

Abstract: This simple, isocratic LC-UV analysis of cannabinoids provides complete resolution of 16 cannabinoids, allowing accurate quantitative potency and profile data to be reported. All compounds are separated to baseline in a fast, 9-minute analysis, making this method suitable for high-throughput cannabis testing labs.

Faster Semivolatiles Analysis with a Scaled-Down Method and GC Accelerator Kit

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/Environmental/env_EVAR2837-UNV

Abstract: 

Scaling down GC-MS columns and conditions can result in faster semivolatiles analysis times and increased sample throughput, but only when done correctly. In this technical article we demonstrate how to scale an existing method on a traditional format (30 m, 0.25 mm ID, 0.25 µm df) arylene-type column down to a 20 m long, 0.15 mm ID, 0.15 µm df column. By using a properly scaled column and method along with a GC Accelerator oven insert kit, the same separation was achieved with a saving of six minutes per injection.

Increase Sample Throughput with New 15-Minute, Low-Level PAH GC-MS Analysis

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/Environmental/env_EVSS2836-UNV

Abstract: 

Polycyclic aromatic hydrocarbons (PAHs) are analyzed at low levels around the world in order to protect human and environmental health. The PAH GC-MS analysis shown here uses SIM mode and column and method parameters scaled down from a commonly used semivolatiles method. Good chromatographic results were achieved down to 0.05 ng on-column in a fast, 15-minute analysis time.

Get Equivalent GC-MS Results Faster with Restek’s GC Accelerator Kit and EZGC Method Translator

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/General-Interest/gen_GNAR2823-UNV

Abstract: 

Have a reliable method, but need results faster? EZGC method translation software makes it easy to get an equivalent separation in less time. By moving to a shorter column and adopting the translated method conditions, you can significantly reduce your analysis time. Agilent users can further speed up their analyses by installing a GC Accelerator oven insert kit.

Simplified Methylmalonic Acid Analysis without Derivatization in Human Plasma by LC-MS/MS

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/Clinical-Forensic-Toxicology/cft_CFSS2829A-UNV

Abstract: 

Methylmalonic acid analysis is an important clinical test for diagnosing vitamin B12 deficiency as well as methylmalonic acidemia. Methods typically require extensive sample preparation, which involves significant time and expense. The LC-MS/MS method developed here offers a much simpler alternative, providing complete chromatographic resolution of isobaric analytes from the direct injection of a protein crash sample supernatant onto a Force C18 column.

LC-MS/MS Analysis of Urinary Free Cortisol and Cortisone without Matrix Interferences

Published By: Restek Corporation

Year of Publication: 2018

Link: http://www.restek.com/Technical-Resources/Technical-Library/Clinical-Forensic-Toxicology/cft_CFSS2824-UNV

Abstract: 

In general, LC-MS/MS analysis of urinary free cortisol and cortisone can provide better specificity than immunoassay-based methods. However, it is critical that the analytical column has the proper selectivity for chromatographically separating cortisol from isobaric matrix components. In the method presented here, complete separation of the target analytes and matrix interferences was obtained in a 3-minute analysis on a Raptor Biphenyl column.