There is No Time to Waste: Low-Pressure Gas Chromatography–Mass Spectrometry is a Proven Solution for Fast, Sensitive, and Robust GC–MS Analysis

Author(s): Steven J. Lehotay2, Jaap de Zeeuw1, Yelena Sapozhnikova2, Nicolás Michlig2,3, Jana Rousova Hepner1, and Joseph D. Konschnik1

1. Restek Corporation, 2. Eastern Regional Research Center at the U.S. Department of Agriculture, 3. Programa de Investigación y Análisis de Residuos y Contaminantes Químicos (PRINARC), in the Facultad de Ingeniería Química at the Universidad Nacional del Litoral

Published By: LCGC North America 38(8)

Year of Publication: 2020


Abstract: Low-pressure gas chromatography (LPGC) has been known to be advantageous compared to standard GC since Giddings first described the concept in 1962, but a practical solution for its use eluded analytical chemists until the year 2000, when de Zeeuw fashioned a simple guard column restrictor concept to maintain positive inlet pressure for a wide-bore analytical column under vacuum. Initially introduced as rapid mass spectrometry (MS), de Zeeuw’s invention made LPGC practical in nearly any GC application using MS for detection. Lehotay and associates have demonstrated the advantageous features, excellent performance, and practical utility of LPGC–MS in dozens of publications since 2001. In our experience, LPGC–MS is the most practical and beneficial fast-GC technique available to achieve <10 min analyses in applications that typically take 20–40 min. Sample capacity and column robustness are increased greatly using LPGC to permit large-volume injection with standard inlets without column maintenance, and, because vacuum conditions generate taller and narrower peaks that are still suitable for standard MS data acquisition rates, sensitivity is also increased. Furthermore, enhanced selectivity of detection using modern MS tools and software compensate for reduced chromatographic peak capacity. In our view, LPGC–MS should be the first option for evaluation in many GC–MS applications to provide fast, sensitive, and robust analyses.

Automated Inline Pigment Removal for the Analysis of Pesticide Residues in Spinach by Liquid Chromatography Tandem Mass Spectrometry

Author(s): Sharon A. Lupo, Randall L. Romesberg, Xiaoning Lu
Restek Corporation

Published By: Journal of Chromatography A

Year of Publication: 2020


Abstract: An automated inline sample preparation (ILSP) method has been developed for pesticide residue analysis in spinach by LC-MS/MS. Chlorophyll pigments and other matrix constituents were removed from the sample extract using a UHPLC system equipped with an auxiliary pump, 6-port high pressure switching valve, and dual-directional ILSP cartridge containing bonded silica. The new procedure was evaluated as an entirely separate workflow using a simple solid-liquid extraction and as part of a cleanup strategy in conjunction with QuEChERS. Accuracy and precision experiments were conducted in spinach at two concentration levels (n=6). Of the 63 pesticides tested, 86% (0.005 mg/kg) and 100% (0.05 mg/kg) displayed average recoveries within 70-120% and RSD values ≤20% for the ILSP method. In addition, low to moderate matrix effects (<50%) were calculated for 95% of the analytes. Overall performance of the proposed method was found to be better or comparable to a traditional QuEChERS procedure utilizing AOAC formulated salts and dSPE sorbents, while significantly reducing the amount of pigments reaching the MS source. The ILSP workflow is a simpler procedure with fewer steps that require less time than traditional extraction and cleanup techniques.

Routine LC Maintenance: Simple Steps to Preventing Unexpected Downtime

Published By: Restek Corporation

Year of Publication: 2020


Abstract: Routine LC maintenance will keep your instrument performing well and minimize downtime for unexpected repairs. In this article, we explore how to develop an effective preventative maintenance plan.