Thursday 28 October 2010

Help on: Developing a HPLC Method for Veterinary Drugs


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 trying to develop a HPLC method for some veterinary drugs. I am using a C18 column 250mm x 4.6 mm, 5u particle size. The mobile phase I’m using has a composition MeOH: 5% GAA in water, 98:2 (v/v). During the analysis I'm observing that between analyses of the same sample, the RT for the drug shifts in each run. The RTs for 5 successive injections are: 8.1 min, 8.2 min, 8.3 min, 8.4 min and 8.2 min.”

“The retention time shifts that you are experiencing could be due to a number of different factors, the most common three being variation in temperature (are you controlling the column temperature?), insufficient column equilibration (prior to any injections and between injections), and changes in mobile phase composition (how are you mixing the mobile phase? If it is premixed this is unlikely to be the source of the retention time variation).

Regarding your choice of mobile phase, the proportion of organic is very high at 98% methanol. The analytes must interact very strongly with the column. Have you considered using a less retentive phase, such as C8? This may reduce your consumption of organic solvent and give you more room to manoeuvre when selecting optimum conditions for your method.”

Wednesday 13 October 2010

Free e-Learning Module on HPLC Instruments

We are pleased to introduce a new format to our UTrain e-Learning portfolio: interactive training modules. Consisting of video combined with interactive content, these modules will be available to purchase as web-based training, either hosted by us on e-MTS or on your own learning management system, and also on CD-ROM.

View the demo now and contact us to discuss your requirements.

Tuesday 12 October 2010

MTS Recommends... Quantitative Open-Access HPLC

'Quantitative open-access HPLC analysis: a new calibration approach' by Phil Borman, John Roberts, Barbara O’Reilly, Robin Attrill, Ian Barylski & Keith Freebairn, Pharmaceutical Technology Europe, October 2010

This article describes a calibration technique used by GSK which enables the estimation of yields in solutions and the assay of isolated solids, so that synthetic chemists can use open access instruments for these analyses. The response factors for a specially selected external standard and that of the analyte are used in the calculation. This will be a useful read for labs using open access instruments.

Friday 8 October 2010

MTS Recommends... From Molecule to Medicine

This 6 minute film explains the various stages for a pharmaceutical company to develop new medical cures. It clearly shows what processes occur in conditions of sickness and how scientists use their knowledge to discover new, innovative drugs to help patients worldwide. Made by NORVELL JEFFERSON, a Belgian audiovisual production company.