Making a Great Connection Sep 1, 2006 By: John V. Hinshaw

Gas chromatographs contain a large number and variety of fittings, ferrules, tubing, and connections, all of which must be properly assembled, tightened, and leak-free if the system is to perform at its best. This month, John Hinshaw discusses how to make, maintain, and troubleshoot various types of connections used in gas chromatographs.

Modern Techniques for the Extraction of Solid Materials - An Update Sep 1, 2006 By: Ronald E. Majors

Traditional methods for the sample preparation of insoluble solid materials have represented one of the more time consuming and labor intensive efforts in analysis. In this installment of "Sample Prep Perspectives," Ron Majors examines modern sample preparation methods for solids that often involve increased temperature and higher pressure to speed up the extraction process. In addition, modern sample preparation methods have been automated to relieve analysts of the drudgery associated with traditional methods. Here, he reports on automated Soxhlet extraction, supercritical fluid extraction, pressurized fluid extraction–accelerated solvent extraction, and microwave-assisted extraction and updates earlier coverage.

Simultaneous Determination of Positive and Negative Counterions Using a Hydrophilic Interaction Chromatography Method Sep 1, 2006 By: Donald S. Risley, Brian W. Pack

The objective of this work was to develop a universal high performance liquid chromatography method that is capable of simultaneously retaining and separating both cations and anions within a single chromatographic analysis for the purpose of quantification in pharmaceutical products. A zwitterionic stationary phase operated in the hydrophilic interaction chromatography (HILIC) mode in conjunction with evaporative light scattering detection was investigated for the separation and quantitation of 33 commonly used pharmaceutical counter ions, 12 cations, and 21 anions. Using a single gradient chromatographic analysis, both anions and cations were easily separated from each other in addition the parent pharmaceutical molecules also were separated.

Gradient Performance Problems - A Case Study Sep 1, 2006 By: John W. Dolan

There always seems to be one more way an LC system can fail.

Analysis of Volatile Bacterial Metabolites by Gas Chromatography–Mass Spectrometry Jun 1, 2006 By: William L. Wood, Daniel J. Higbee, Melanie Gooldy, Scott Glogowski, Rich Fitzpatrick, Richard J. Karalus, Troy D. Wood, David J. Mangino

The authors describe a new method for the identification of key volatile organic compound (VOC) markers.

Syringes for Gas Chromatography Jun 1, 2006 By: John V. Hinshaw

John Hinshaw takes a look at how choosing a suitable syringe for a specific application can be difficult, especially if the inlet system has special requirements; choosing the wrong syringe can cause significant problems.

Miniaturized Approaches to Conventional Liquid-Liquid Extraction Jun 1, 2006 By: Ronald E. Majors

Liquid-liquid extraction (LLE) is among the most widely used sample preparation methods. In this month's installment of "Sample Prep Perspectives," Ron Majors discusses newer LLE approaches that offer significant advantages over classical methods.

How to Retain Polar and Nonpolar Compounds on the Same HPLC Stationary Phase with an Isocratic Mobile Phase Jun 1, 2006 By: Joseph J. Pesek, Maria T. Matyska

Separation and retention of both polar and nonpolar compounds by the same stationary phase can be a useful approach for analyses of complex samples with a broad range of chemical properties.

Method Validation and Robustness Jun 1, 2006 By: Michael Swartz, Ira Krull

The authors define robustness, introduce a few approaches to designing a robust study, and discuss data analysis necessary to help ensure successfull method implementation and transfer as a part of method validation protocol.