Thursday 26 April 2012

Help on: Retention Time Change


Do you have any problems relating to analytical chemistry for pharmaceuticals or training? Send your questions to the MTS helpdesk using our contact form.

“I am working with TFA in my mobile phase and my analyte elutes at 13.5 minutes. In the same day the retention time has changed by 0.2 minutes. It is normal? I'm using an isocratic method.”

"If you experience a change in retention time during a run then it indicates that something in the method conditions is changing, most likely a temperature or mobile phase pH shift. In my opinion, 0.2 minutes is a very small change for a peak at 13.5 minutes (~1.5%) and may not necessarily be a big problem. However if the shift continues, it may become an issue. I suggest that you check the following:
  • Is the column temperature controlled? If not, then that is probably the source of the RT shift and if you have no way to introduce temperature control then you will experience RT shift. If you do have a column oven, then ensure that it is working correctly and that there is a suitable length of tubing to and from the column also being temperature controlled.
  • Is your analyte ionisable? TFA is a very useful acid modifier for HPLC mobile phases and is successful for a range of molecules. However it is an acid modifier rather than a buffer and so some ionisable analytes may not be suitably pH controlled using only TFA.
If the problem does not escalate then it is probably fine to continue. I suggest that you monitor the retention time change. For example, does it slowly change over the course of the run or suddenly shift, or does it always change in one direction (increasing or decreasing retention time)?"

Tuesday 24 April 2012

HPLC Training Courses in Dublin, June 2012

Mourne Training Services is delighted to offer four HPLC training courses from our 'How to...' series which are designed to provide both theoretical and practical advice, enabling straight to lab application. Whether you are a complete beginner or are already using HPLC we can help to develop your expertise.
The courses are split into three topics:
1) an introductory programme which will demystify the parameters listed in HPLC methods;
2) a full treatment on troubleshooting HPLC systems and thus reducing downtime; and,
3) a two part method development course in which a strategic approach will enable you to develop HPLC methods quickly and efficiently. The two parts can be taken together for a complete method development course, or separately for maximum flexibility.
Book before 11th May 2012 for discounted course fees
We are offering the following discounts until 11th May 2012:
€275 per person per day, 2 days for €520 or 3 days for €740.
Academic discounts and group discounts also available up to 11th May, contact us for a quote.
After 11th May all courses are charged at full price of €350 per person per day.
Note: All prices are quoted exclusive of VAT.

Included in the Course Fees:
  • Comprehensive handouts for each course containing useful reference data.
  • Free tools to help you use HPLC efficiently, For example: Column equilibration calculator; Calculator for preparing mobile phase reagents; Method development calculator; Troubleshooting lookup tables; Calculator for working out how much mobile phase to prepare (for both isocratic & gradient methods).
  • A Certificate of Attendance. There is an optional post training assessment to obtain a Certificate of Training.
  • Expert Advice from the MTS trainer on your HPLC problems, both on the day of the training and after the event.

The Courses:

5th June 2012 How to Run HPLC Methods
If you book on this course before the 11th May, we will give you a free copy of the book, 'An Introduction to HPLC for Pharmaceutical Analysis'.
The training runs from 9:00am to 4:45pm each day. The venue is the Metro Hotel Dublin Airport, conveniently located just off Junction 4 of the M50.

Click here for a printer friendly flyer for these training courses.

Wednesday 18 April 2012

MTS Recommends... Efficient HPLC Method Development and Personal Reflections

Efficient HPLC Method Development and Personal Reflections
By: Lloyd R. Snyder, 1st April 2012, LCGC North America
'A pioneer in high performance liquid chromatography reflects on his career and how "enlightened trial-and-error" can reduce the effort involved in method development.'