Chromatography Forum

Dear All

I am a novice to HPLC. I have several question to ask:

1. how good is it of the computer-aided HPLC method development? What is the best software so far? Are they free?

2. for two HPLC graph I attached to this post, what factors do you think are responsible for the HPLC change from above one to the one below it? Capacity factor? Efficiency? Or Selectivity? And can you explain what makes your conclusion? How to change these three factors in a practical run, especially the "Selectivity"?

3.Can anyone suggest a book or on-line source (preferrably with a lot of examples and explanations) that can help me to learn the basics for HPLC method development? how to get information from a known HPLC trace, like in question 2?

Thank you so much for your help!

Dear littlewenwen

2) the HPLC factors that can change chromatography are either replacement of column or change in the composition of the mobile phase. You can observe that 6th and 7 th peak has smaller retention in the second graph and also come before the 5th peak. There are changes in the capacity and selectivity. The second graph probably is a result of the change in the mobile or stationary phase (compared to the first graph).

3)You could try the book: Prictical HPLC Method Development by Lloyd Snyder and Joseph Kirkland

Best regards

Hi

are these really chroms from you?
It seems to me like these picture are out of a vendors column broschure? (Sorry if I am wrong)

For me it seems like a change in the pH of the mobile phase occured form the upper to the lower one. (suggestion upper pH3 and lower pH 10)

Peaks 1-3: are neutral components
6 & 7: are acidic ones
4: slightly basic, maybe amphoteric?
5: basic component

What we see is that the Chromedia is growing and gaining popularity. Chromatdia a practical online encyclopedia with numerous of practical examples. The content is written by well respected scientist, who also post here on this forum.
Check www.chromedia.org or send me an e-mail and I will provide you with the contact details.

thank you all for great help.

The HPLC I attached is from some website. It looks very interesting and mysterious to me. That's why I asked these questions.

It looks to me that "Capacity Factor" and "Efficiency" are independent and easier to manipulate, but is there a common way to change the "Selectivity" between two compunds? Will the "Selecttivity" change affect the other two factors?

can anyone give some suggestion on my first question:

1. how good is it of the computer-aided HPLC method development? What is the best software so far? Are they free?

Hi littlewenwen,

but is there a common way to change the "Selectivity" between two compunds? Will the "Selecttivity" change affect the other two factors?

As the other posters suggested above, the selectivity can be manipulated by changing mobile phase (e.g. pH, salt concentration and/or nature, organic modifier etc.), stationary phase (column) and temperature.

The selectivity by it self will not affect the other factors, but the changes introduced in order to manipulate it will most probably influence them maybe positively, maybe negatively – it all depends on the application.

how good is it of the computer-aided HPLC method development? What is the best software so far? Are they free?

The most “famousâ€

Thank you so much!

There is a basic tutorial on HPLC that should answer your questions about definitions (selectivity, efficiency, etc.) on the LC Resources web site:
http://www.lcresources.com/resources/getstart/index.htm

Once you get a good grip on HPLC I suggest this book. I would have to say you can separate almost anything if you have a good grasp on HPLC solvents.

[quote="danko"]....The most “famousâ€

Hi littlewenwen,
This Blog ( http://bookfiesta4u.blogspot.com/search/label/Chemistry ) contains some of the good books on chromatography.

I found it very useful...

thank you all for great help