Liquid Chromatography

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...

Sometimes I don’t know whether to be amused or dismayed when I am presented with an HPLC method. Whether it is a method question from one of the readers or a paper to review for the 'Journal of Chromatography', it is a bit surprising to me how often...

My first “real” job was working for Technicon Instruments Corp. in Tarrytown, New York, USA. My boss was Lloyd Snyder, who was to become a close friend and who has been my business partner for almost 26 years. Little did I know what my future had in...

Save 50% on the cost of your LC-MS! Now that I have your attention, perhaps I shouldn’t make such a grand claim – maybe only 40%. Of course I’m talking about operating costs, not the purchase price, but if it means that you can do the work of two...

Q: I have observed peak splitting in my chromatograms when I inject the sample in tetrahydrofuran (THF) as the injection solvent, but I don’t see any problems when acetonitrile (ACN) is used. I am using a C18 column with a mobile phase of ACN/buffer...

Q: What buffer should I use when I want to optimize the pH of the mobile phase? I normally use phosphate buffer, but I heard that phosphate may not always work. How can this be? I thought that phosphate was a great buffer for reversed-phase HPLC....

In an earlier blog article, we looked at the effect of trifluoroacetic acid (TFA) concentration on retention when the mobile-phase pH was controlled by adjustment with TFA. Much of the time, especially at low pH, you can get consistent results by...

In this technical article you will learn how effective trifluoroacetic acid (TFA) in mobile-phase preparation is and how a buffer can be a better choice if a specific pH is required.

This technical article discusses the best way to wash an ion-pairing reagent from a column.

PEEK (poly ether ether ketone) tubing has become a standard item in the operation of many HPLC systems. It is convenient, inexpensive, and easy to identify the internal diameter. However, some care needs to be taken to avoid problems associated with...

In this technical article you will learn about the procedure for purging air from a reversed-phase column.

Q: I know that retention varies according to the ionization of a compound. If the compound is ionized, the retention generally is shorter than if it is not ionized. Does this mean that I should expect two peaks if the compound is near the pKa, where...

This technical article provides details regarding phase dewetting or phase collapse in an HPLC column.

In this technical article you will learn about the two procedures that are used to make sure that an HPLC equipped with a mass spectral detector (MS) is reporting proper mass information and that the system is properly set to detect the analyte(s)...

In this technical article you will learn how the signal-to-noise ratio (S/N) is an important variable that may influence the performance of your method.