Chromatography Forum

i work in a qc lab for 7 years. we follow SOP's and we cannot make changes. Now i undersand that ,in reality, i don't know what i do for living. i follow the methods and i have no clue why the method developer choose this solvent, that mobile phase, this column, that PH e.t.c. Joining this forum i started to wonder for all these and i want now to see my 8-9 hours per day in a different point of view. I need your help. These are some of my questions. There will be more. Thanks in advance.
*when we prefer normal phase from reversed phase chromatography?
*how we choose the solvent we'll use for an analyte?
*how we choose the mobile phase?
*why some buffers have half Na2HPO4 and half NaH2PO4? why both? and why need a buffer? when the PH may change and we want to prevent it? And i am not sure i understand how we choose what the PH must be. And why we fix the PH with TFA and not acetic acid, or when we fix the PH with triethylamine and not NH3?when we choose to use sodium lauryl sulfate or tetrabutylammonium hydrogen sulfate (or hydroxide)?
*how we choose the columns to use?
i need to know what i am doing and why i am doing it. It's the 1/3 of my everyday life. i've spent a lot of hours searching this site and i"ll keep doing so. please help me with some answers or some links.Thanks
(please don't tell me that i need to take a method development course)

Hi Friend.

If you wish to transition from a Rock-n-Roll chemist to a Chromatographer, you've come to the right place.

Chromatography is what you call a "mature" science. Its fundamentals have been around for decades, so it is not as though we're hanging on to some fast-paced science for dear life. Go read the fundamentals then come back and ping us with specific questions. There are a lot of good men and women here who love to talk shop.

What is your educational background?

You may not know the answers to your questions but you want to learn. This forum is a great start to build your knowledge base, but is also problem specific and may not directly correlate to your actual work. I imagine your company would be un-willing to send a QC chemist to a Method Development course and it's not the answer you want. It's easier to listen to 3 days of a condensed lecture by Tom Jupille, however a book such as Practical HPLC Method Development is also good start. It discusses when to use a buffer, ion-pairing reagent, or various which solvent (acetonitrile or methanol), etc. Most companies have books available or ask to buy one, most method develpment chemists have books, ask to borrow one, go to the library and check one out, most universities have a good selection.

There is a wealth of tools available such as books, magazines (LC/GC), and free webinars.

i am a chemist but during university time i was playing with a band in a rock live club and i continued to do so for years after the graduation. When i found the job as an analyst i had forgotten a lot about chemistry. But following the specs it was not much of a problem. Now i wanna know what i am doing. I know my questions are too general but i guess someone can give me some brief answers and some links(in the forum) to find my way. Thanks

There is a lot of good, free information. Check out our web site:
http://www.lcresources.com/wiki/index65 ... Q:MoreInfo

I haven't kept up with all the available links, but it's a place to start, and I'm sure others will chime in with suggestions.

I would never trade being a rock musician to being a chemist, even I know a lot about chromatography

It's great to ask the questions. I work in a research organisation and over the years we have had many people come to interview with years of experience in QC labs, but their understanding of thier own chromatography was amazingly low. Even simple questions like - "here is an HPLC column what does the information on the label mean?" stumped several interviewees.

It is easy to fall into that trap when working in such an inflexible environment, but for your own development please keep asking the questions, we all had to learn once. Increased automation may have helped in many aspects of our work but the subsequent reduction in staff numbers often leads to limited oportunities to learn from more experienced analysts.

initiative in such organization is a minus. Employees in labs like that expect to deliver results as robots. They are usually paid less but exploited more . In order to find a fulfilling job you need to be in research and development organization. I have a team which develops and testes new stationary phases and supports and we come up with something new every week. There is nothing boring about this and I usually try to explain to my employees why they are doing particular task, how columns and equipment works, and what are the laws and mechanisms behind every separation.

In addition to the good advice regarding books etc, visit

http://www.chromatographyonline.com/

to subscribe to the free monthly magazine "LC-GC", which is a gold-mine of info. regarding columns, mobile phases, method development, trouble-shooting etc.

You will not regret any hours you put into learning the fundamentals; as Vlad says, HPLC in an R&D setting is the place for never being bored.

Good Luck with things, and we expect you to be in a better place (physically or mentally) within a couple of years !!!!!

thank you all for your support. i am diving into the books now but every now and then i will be back to ask specific(this time) questions about daily issues about my work. Is that ok? And you will give me specific answers and not just advice is that ok? thanks again.

Not many people get them anymore but I found a lot of information of the type you are looking for in chromatography product catalogs. The Restek catalog has a good tutorial on basics of HPLC as does Phenomenex. I have a nice wall poster from Phenomenex I put up for new trainees that has the basics of pH, functional groups and mobile phases at a quick glance. I also have the SEILC small poster hanging up titles "A Guide for HPLC Separation of Small Molecules" maybe Vlad can hook you up with one of those.

Sometimes the little things help a lot in understanding our work.

Our website is very informative in terms of mechanisms of interactions. We have several method development guides and tutorials. Here are few of them:
http://www.sielc.com/MethodDevelopment_ ... dType.html
http://www.sielc.com/MethodDevelopment_Guide.html
http://www.sielc.com/Literature_Brochures.html

I can send you a wall poster version of the first link, which basically asks you about properties of your molecules and gives you advice on mobile phase and column selection.

*why some buffers have half Na2HPO4 and half NaH2PO4? why both? and why need a buffer? when the PH may change and we want to prevent it? And i am not sure i understand how we choose what the PH must be. And why we fix the PH with TFA and not acetic acid, or when we fix the PH with triethylamine and not NH3?when we choose to use sodium lauryl sulfate or tetrabutylammonium hydrogen sulfate (or hydroxide)?
*how we choose the columns to use?

Please do not try to learn from established lc-methods. Many published lc-methods are only trash! To read some of the recommended books is a beginning, but if you would go in-deep to chromatography you also need the experience from real performed experiments. I think you need a new job.

New job? In my country i'm considered to be extremely lucky for having one. And even luckier for i get paid every month. I understand that many of the methods we use are rubbish but through my questions i'm trying to learn, not for these specific methods, but for chromatogapy in general. Although i can see that one method is no good, i am not always sure what exactly is the problem. I believe that ,if the more expirienced of you, see our methods, you would find the mistakes just by reading them. I cannot do that.