Help on: Problem with the first injection from HPLC vials

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

Question: “When I use a single vial for a series of standard injections the area for the first injection is often lower than that for the subsequent injections. What could cause this?"

Answer:
“There are a variety of potential reasons for injector repeatability problems but the most likely explanation when the first injection from an individual vial gives a lower response than subsequent injections is that the vial was overfilled. This creates a vacuum when the needle pierces the cap and withdraws the test solution and thus the syringe does not withdraw the correct amount. On the next injection the vacuum effect is no longer present and thus the syringe withdraws the correct amount. To prevent the problem, take care to leave a small headspace when filling a vial rather than completely filling the vial.”

Separation Science Europe 2011

I will be presenting "A Comparison of Recommended Strategies for Reversed Phase HPLC Method Development" at the Separation Science Europe 2011 Conference, on the 10th October.

Abstract:
The benefits of using a strategic approach for developing HPLC methods are easily apparent. The numerous possible chromatographic parameters in a typical HPLC method make choosing the most suitable ones for a particular separation very daunting. In particular, how to select one column from the hundreds available? There are a number of different strategies which can be applied, these include: trial and error, changing one variable at a time; finding a method in the literature or finding a method in the literature for a similar compound; and sophisticated column screening experiments combined with computer modelling, peak tracking methods, experimental design and column comparison tools. In this presentation, current recommended method development strategies are reviewed and compared to give delegates an appreciation of the types of strategies which may be applied, so that they can identify the one which is most applicable for their method development needs.

How to Troubleshoot HPLC

MTS will continue to work with Phenomenex in the delivery of HPLC training seminars in the UK with a series of troubleshooting courses in November. The dates and locations are as follows:

8th November - Edinburgh
9th November - Crewe
15th November - London

Course price is £195 + VAT per delegate. The price includes: Full day training (including post training assessment), course literature, technical brochures, lunch and refreshments.

If you are interested in attending, contact Phenomenex:

Tel: UK: 01625 501367 or email: ukinfo@phenomenex.com