Smaller is better - How to use 0.15mm Capillary Columns

There are still obstacles to switch from the very common internal diameters of 0.32 mm or 0.25 mm to the "faster" columns with 0.15 mm ID. This article will show how easy it is to adapt your methods and to what you have to pay attention to when doing the conversion.

Introduction

The most popular capillary column dimensions in modern day chromatography are beyond doubt the 25 m/30 m x 0.25 mm versions. These columns are usually coated with either polydimethylsiloxane (VF-1ms) or poly(phenylmethyl)siloxanes types (VF-5ms) of liquid phases with layers of 0.25 ìm. The wide spread use of this particular column dimension is mainly based on their applicability in a wide variety of samples types, injection modes and detector types. In addition, they offer a good compromise between speed of analysis, resolution, and sample loadability. As such they are normally the first choice for lab techni-cians. However, the traditional 250 ìm ID columns are often outperformed in terms of speed of analysis, sensitivity and bleed performance by 150 ìm ID columns.

These 150 ìm ID columns were carefully developed with a focus on improving this speed of analysis while at the same time maintaining much of the sample capacity, retain-ing a wide applicability and instrument compatibility. This article offers some practical guidelines for updating your existing application into a high speed application based on 0.15 mm columns using the same equipment: