after 500-600 injections,"he said.
The answer lay in a relatively new stationary phase, a material featuring a non-porous core surrounded by a`shell'
of porous stationary phase. This material had been shown to exhibit extremely tight particle size distribution and
consequently excellent separation efficiencies and lower backpressures compared with similar size totally porous
materials."Applying these columns to our generic methodologies we were indeed able to demonstrate these
excellent separation efficiencies at backpressures of approximately 6000-7000 p.s.i. and furthermore we discovered
that the separation remained excellent over the analysis of many thousands of our typical protein-precipitated plasma
samples. Thus we were able to fully define the highly robust generic UHPLC analytical method required to support our
business needs,"he said.
The methodology has been implemented across the whole department (as well as another DMPK department
within GSK), enabling the successful transference to UHPLC methods of analysis. The consequent reduction from
3-4 minutes per sample to <1.5 minutes per sample has also given the department more analytical capability and
flexibility."Should one LC-MS system fail, it is possible for an analyst to transfer the methods and samples and run
as an additional batch on another instrument along with a colleague analysing his or her own samples on that
instrument � and both still have their analyses ready for processing by the following morning,"he explained. For
smaller batches of samples, it is even possible to provide DMPK results on the same day they are delivered, extracted
and analysed. Finally, the effectively greater than doubled sample capacity of the systems has reduced and in some
cases removed the need to buy additionally LC-MS systems at considerable financial savings to the company.
The department now has sufficient capacity to meet its needs and so the focus will shift from speed towards
improving sensitivity and developing high efficiency separation methods for lower throughput applications such as
metabolite identification.
13research round-upseparation science -- volume 1 issue 4

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