Liquid Chromatography

In this article we’ll consider the last of the initial set of measurements, the column plate-number, N. This is also called the column efficiency, and is calculated as

This technical article considers the factors affecting chromatographic selectivity.

This technical article looks at diagnosing problems with our HPLC separations. 

This technical article looks at several ways to estimate column dead-time.

This technical article looks at some of the basic calculations used in HPLC, with an emphasis on their practical utility for evaluating separations, developing methods and isolating problems. The first in line is the retention factor, k, often...

In may cases chromatographic processes can be simply described, wrapped in a neat package, and tied up with a pretty bow. This in not the case though with column overload.

There are two aspects of buffer lifetime. One has to do with how long it is effective as a buffer and the second is related to other buffer properties – in particular, microbial growth in the buffer solution.

In this article, we consider whether it is ok to back-flush a column. If a C18 column is used for a routine analysis and the pressure has risen, as in this example, if the column is reversed and unplugged will this be ok or will be the column be...

Shifting retention times within a sample batch can be a real source of headaches in the routine HPLC laboratory. Previously we talked about the kind of retention drift experienced by some HPLC methods for the first few injections. This often is...

How many of you have experienced this? You think you’ve fully equilibrated the HPLC column by running mobile phase through it for 30 min, but for the first 3 or 4 injections, the retention times drift a little, finally settling down after half a...

In this technical article you will learn about which properties are necessary when choosing a compound to use as an internal standard. 

In this technical article you'll learn how an internal standard is used in quantitative analysis.

It is easy to take knowledge for granted, especially when you’ve been involved in a field for a long time, as I have with HPLC. One of those areas is about how to protect the column. In the training courses we teach, Tom Jupille and I jokingly...

In an earlier blog, we looked at the processes of sample filtration or centrifugation as a means of reducing or eliminating particulate matter from the injected sample. As I mentioned, I prefer centrifugation, because it is easy, inexpensive and...

In previous blog posts we've talked about various aspects of buffers. We saw that some buffers were better than others and that there were certain buffer-preparation practices that should be avoided. This prompted one reader (I.M.) to remind me of...