How do I choose the right HPLC column?

So Step 1 - look in a column catalog. It’s gonna give you a guaranteed result.

OK let's say that you don't have a column catalog. Or let’s say that your chemical isn’t in one. Let’s say that you are sitting there saying, “Well Lee if I knew all of that I wouldn’t be asking you for advice.”

So that is a valid point. Let me take you to the next step.

In HPLC we have dozens of columns out there, but there is one column that dominates. If you look at all the column sales, about 85% of the column sales are reversed phase columns.

Why is that? To me that means that 85% of the separation problems must be solved by reversed phase. Not every one, 15% won't be. But let’s play the odds.

What you want to do is to choose one really good reversed phase column. You want to buy the best base-deactivated C-18 column that you can get.

C-18 is going to be your most useful reversed phase column. There are dozens of different C-18 columns out there. What you want to find is the most modern C-18 column out there.

So here is a weird thing. When you look in the catalog they are going to list their oldest columns and their newest columns. And catalogs won’t really tell you that their old columns are lousy. That catalog - I hate to say it - is filled with lousy columns.

It doesn’t mean that Agilent makes lousy columns, it means that there are old-fashioned columns that they still make for old-fashioned applications.

If you are starting a new application you want to start with today’s best technology.

So my favorite column is eclipse plus made by Zorbax, by Agilent. There are have their SB-C18 that is also fantastic it is their #1 selling column. I personally like the Eclipse Plus.

But I won’t limit it to my Agilent friends. Waters make a couple of great columns. Waters SunFire, a beautiful column, a beautiful C18 base deactivated column. They also make one called XBridge. A different technology, very high-pH stable, an excellent column.

My friends at Phenomenex make a column called the Luna C18, the #1 selling silica in the world. There is a newer version called the Gemini C18 - I don't like the cute names but I like the column. The Gemini C-18 is the latest and the greatest out of Phenomenex.

I feel bad for all the companies that I did not mention. There are other great ones out there.
But you start with a good base deactivated C18 column. My next piece of advice is you buy a column with the most efficiency you can get. We haven’t defined efficiency yet. Come back to one of my lectures and I will define efficiency for you. But it is a measure of the skinniness of the peak.

So when you are entering method development I have no idea how much efficiency that I need, so let’s start with the longest with the most efficiency. If that works and I have empty space I can go to a shorter column to save time. But if I start with a short column, it may not work and then I would have to go to a long column. So in other words, start with a really long, really high efficiency base-deactivated C18 column. In my world that would mean a 10 cm/1.8 micron, or a 15 cm/3.5 micron, or a 25 cm/5 micron - old fashioned!

Any of those are brute force columns.

So to summarize: good c18 base deactivated, high efficiency. Start with that. That one column will handle most of the applications out there in the reversed phase world.

So there’s your go-to guide for choosing the right column in HPLC

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