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May / June 2013
it was more ‘heart- cutting’ than selective 2D-LC but nonetheless the work was very elegant. She addressed the problems posed by poorly retained
compounds with low UV chromophores. She mentioned the importance of
orthogonality of detection (corona discharge aerosol detection (CAD; shows fumaric, tartaric and citric acid as well as sodium ions), MS) as well as the phases in the two dimensions. In the context of MS detection, the second dimension could be used to help reduce ion suppression. HILIC and normal phase for chiral had both been used in the second dimension. One of the main points of discussion was a prostate cancer development candidate with three chiral centres (presumably the same compound that Dong from the same company had been talking about in another session - there can’t be too many such beasts doing the rounds). Even using a highly powerful reversed- phase chiral screening system it had not been possible to separate all eight possible stereoisomers.
The final speaker in this session was the “Presider” himself, Dwight Stoll. He elaborated in detail on the merits of selective 2D-LC versus true 2D-LC. It was all about the sampling rate from the first dimension. If this is not high enough then it would be possible to mix back in near- by peaks which had been successfully already been separated in the first dimension. It was therefore better to focus on using the second dimension only for groups of peaks that appeared as ‘multiplets’ in the first dimension.
In the Thursday pm session on SFC (note that SFC was not restricted to just one session; for example a talk by Patricia McConville (Waters) on method development with carbon dioxide mobile phases in “convergence chromatography” appeared elsewhere). The success of the most recent resurgence in the technique was attributed to more rugged hardware, albeit there are still some issues when using an active splitter. As a consequence, SFC was now perceived to be maturing rapidly. Part of this maturation was the use of water as an additive. While this was very good for polar compounds, it was not
used at MSD, especially for coated CSP, unless it proved to be a necessary requirement. However, Christine Aurigemma (Pfizer) made a very strong case for the use of water as an additive despite the potential problem of hydrolysis. Amongst other pharmaceutical applications, she described a long string of examples of good separations of polar compounds, including glucose / fructose, nucleotide monophosphates, epinephrine / norepinephrine and hormone replacements that would not normally be associated with SFC. She also cited the possibility of using electrospray ionisation MS detection as an advantage of using water as an additive. Of course, chiral SFC was responsible for the previous (3rd out of 4) coming of SFC and no SFC session would be complete without some chiral separations. Manuel Ventura had routinely been using SFC successfully for chiral screening for some time, typically using 7 CSP (Luxcell-2 and the Daicel IC, IA, OJ, AS, OD, AD (or AD-H). However, there had been difficulty in also achieving achiral separation from other sample components. To this end, Ventura had coupled his chiral screening system to an achiral screen in which 8 achiral polar phases had been evaluated. A 4-ethylpyridine and a HILIC-diol phase had looked most promising in terms of peak shape and range of successful achiral separations. The presentation of Ray Mclean (Merck) on “Remaining Current in SFC: Optimising an Aging SFC Laboratory” also strongly featured chiral work, for screening and for preparative work involving 5 g or less (higher amounts being outsourced). With respect to screening he had moved from a 5 CSP, 6 mobile phase system to a
parallel operation which took one hour or 42 minutes if 3 µm materials were used. He commented though, “Why just chiral?” and, although, “Merck compounds generally come off early” went on to discuss the use of focussed gradients and SFC of extremely polar compounds.
All-in-all Pittcon 2013 delivered a high quality technical programme, of particular note being the very good use of modern technology by lead separation scientists in major US pharmaceutical companies - so it’s not just about ‘suits’ striking deals around the exhibition!
The Pittcon 2013 programme and abstracts can still be seen. Also some of the presentations were videod and may also be seen (“symposia webcasts”). All of this and preliminary information for Pittcon 2014 at Chicago is at
www.pittcon.org. Remember to bring an overcoat.
The ‘not-so-secret’ Separation Scientist
United Nations Agencies Fund Initiative to Improve Food Safety in Developing Countries
Phenomenex announces that Serena Lazzaro, the company’s global marketing manager for food safety and quality, was selected as a trainer for a recent workshop conducted jointly by the United Nations’ Food and Agriculture Organization (FAO) and the International Atomic Energy Agency (IAEA). The two-week workshop, “Integrated Analytical Techniques to Control Contaminants in Food,” took place last month at the Food and Environmental Protection Laboratory (FEPL) in Seibersdorf, Austria. The training was created for the Latin America and Caribbean network RALACA (Red de Laboratorios de análisis America Latina y el Caribe). Participants in the workshop represented government and nongovernment labs as well as representatives from universities involved in controlling and monitoring food supply in developing countries.
Lazzaro presented an overview of sample preparation and HPLC solutions to analyze contaminants in foods as well as evolving food legislation, international standards and method performance requirements. She also reviewed the differences between screening and confirmatory methods.
For more information visit:
www.phenomenex.com
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