ARTICLES

The Potential of Polymer Monolithic Capillary Columns for the Analysis of Intact Proteins using LC–MS
Bert Wouters.¹ Axel Vaast, Achim Treumann,¹ Mario Ursem,² Jenny Ho,⁴ Martin Hornshaw,⁴ Marc Roes,⁵ Herman Terryn⁵ and Sebastiaan Eeltink¹
LC–MS-based top-down proteomics involves the chromatographic separation and mass-spectrometric characterization of intact proteins without prior enzymatic cleavage into peptides. This article investigates the preparation of monolithic reversed-phase columns with optimized porous structure and describe their performance for the separation of intact proteins. Peak capacities around 600 could be achieved within a 2 h gradient. The combination of high-resolution monolith chromatography with high-accuracy time-of-flight mass spectrometry allowed intact proteins and protein isoforms that differ only in their oxidation state to be distinguished. The article also demonstrates the use of different MS fragmentation techniques to identify and characterize intact proteins.

Rapid Multidimensional Liquid-Gas Chromatography Determination of Saturated Hydrocarbon Contamination in Foods Containing Vegetable Oil.
This article describes a rapid heart-cutting LC–GC method for the analysis of mineral oil saturated hydrocarbons contained in a series of widely-consumed food commodities (vegetable oil, margarine, crisps, and tinned tuna). The automated LC–GC experiments were performed using a system equipped with a syringe-type interface, capable of both heart-cutting and comprehensive two-dimensional analysis. The first dimension separation was achieved on a silica column operating under isocratic conditions (hexane). The heart-cuts were transferred to a programmed temperature vaporizer. After the large volume injection, the target analytes were separated in a rapid manner (~ 9 min) using a micro-bore GC capillary. The overall LC–GC run time enabled the analysis of circa 4 samples/hour. Thirty food samples were subjected to analysis, with various degrees of contamination (from “not detected” to circa 390 mg/Kg) found.

COLUMNS

COLUMN WATCH
Current Trends in HPLC Column Technology
Ron Majors
In this installment, we look at the results of a recent HPLC column survey of LCGC North America readers conducted in late 2011. We examine trends in analytical and preparative column use and purchasing patterns and compares the results with earlier surveys. Trends in mode and stationary phase usage, particle sizes, column dimensions, column lifetime, and guard columns are explored with emphasis on some of the newer column technologies such as sub-two micron (UHPLC) and superficially porous particles. Column purchasing patterns, budgets, pricing, and factors influencing buying decisions also are discussed.

LC TROUBLESHOOTING
LC Trouble Everywhere
John W. Dolan
No matter where LC is used, it is never immune to problems.

GC CONNECTIONS
Headspace Sampling: Instrumentation
John Hinshaw
In this month's installment, John Hinshaw discusses the fundamentals of instrumentation for headspace sampling, including vial thermostatting, pressurization, and transfer to the GC inlet.

DEPARTMENTS
Products
Literature
Event: ISSC 2012, Riva Del Garda, Italy Preview.

Upcoming Webcast:
Using LC-MS-MS to Quantify and Identify Natural Toxins in Food and Environmental Samples
Thursday, 15 December 2011, 14:00 CET; 8:00 AM EST
Natural toxins in food and environmental samples are of increasing concern for human health. This webinar provides information on how LC-MS-MS in general and QTRAP^® systems in particular can help tackle the challenges of quantitative and qualitative analysis of fungal, bacterial, algal, and plant toxins. To learn more and register for this webcast for free please click here.