John V. Hinshaw | Authors

John V. Hinshaw is senior staff engineer at Serveron Corp., Hillsboro, Oregon, and a member of LCGC's editorial advisory board. Direct correspondence about this column to "GC Connections," LCGC, Woodbridge Corporate Plaza, 485 Route 1 South, Building F, First Floor, Iselin, NJ 08830, e-mail For an ongoing discussion of GC issues with John Hinshaw and other chromatographers, visit the Chromatography Forum discussion group at


Essential GC Accessories

Most manufacturers ship gas chromatographs with a small collection of consumable parts and accessories, such as extra ferrules, inlet liners, or septa, and a few instrument-specific tools. In earlier times, some convenience items might have been included as well, like a bubble flow meter or a small set of tools, but now it’s rare to find such things in the shipping boxes. This edition of “GC Connections” lists a number of essential items that should be on hand in every gas chromatography (GC) laboratory, their function, and how to use them effectively.

Fast Gas Chromatography

Fast gas chromatography (GC) has received new attention recently in the form of available enhanced instrument capabilities. This instalment reviews important characteristics and requirements of fast GC: What can fast GC do for separations, and how can laboratories take advantage of enhanced separation speeds?

Sealing It With Septa

While gas chromatographers may take their septa for granted, in fact these small and seemingly unremarkable polymer disks keep air out of the carrier-gas stream when used in an inlet and keep samples intact and uncontaminated when used in sample vials. Choosing the wrong septa can compromise method accuracy and repeatability as well as reduce column life in extreme cases. This instalment addresses septa for inlets and sample vials.