Advances in high-throughput mass spectrometry.

The evolution of high-throughput drug discovery is readily apparent as the pharmaceutical industry continues to stress the rapid progression of new chemical entities and biological agents through drug discovery and development pipelines. Mass spectrometry and high performance liquid chromatography-mass spectrometry have played an instrumental role in the support and advancement of all facets of high-throughput drug discovery. The introduction of new instrumentation has extended the breadth of mass spectrometric-based capabilities from the characterization of high-throughput organic synthesis products to early adsorption, distribution, metabolism and excretion profiling. Additionally, advances in the capacity and throughput of mass spectrometry systems have concurrently led to the introduction of data management tools to address automated data reduction, archival and mining, as well as analytical data integration to chemical and biological databases.

Techniques for increasing the throughput of flow injection mass spectrometry.

Improvements to the design and operation of a Gilson 215 multiprobe liquid-handling system have resulted in a significant increase in the throughput for flow injection molecular weight characterization of combinatorial chemistry libraries. The rapid injection sequence, and subsequent increased sample throughput, is effected by directing the entire mobile-phase flow through each of the injection loops sequentially while isolating or "dead-ending" the remaining nonactive loops. This mode of operation was accomplished by incorporating column-switching valves prior to and following the set of eight parallel injectors. Analysis rates are achieved without sacrificing the integrity of the flow injection peak profile as baseline resolution is maintained for all samples. Using this system, the total analysis time for a 96-well microtiter plate has been reduced to approximately 5 min.

Increasing bioanalytical throughput using pcSFC-MS/MS: 10 minutes per 96-well plate.

The utility of packed-column supercritical, subcritical, and enhanced fluidity liquid chromatographies (pcSFC) for high-throughput applications has increased during the past few years. In contrast to traditional reversed-phase liquid chromatography, the addition of a volatile component to the mobile phase, such as CO2, produces a lower mobile-phase viscosity. This allows the use of higher flow rates which can translate into faster analysis times. In addition, the resulting mobile phase is considerably more volatile than the aqueous-based mobile phases that are typically used with LC-MS, allowing the entire effluent to be directed into the MS interface. High-throughput bioanalytical quantitation using pcSFC-MS/MS for pharmacokinetics applications is demonstrated in this report using dextromethorphan as a model compound. Plasma samples were prepared by automated liquid/liquid extraction in the 96-well format prior to pcSFC-MS/MS analysis. Three days of validation data are provided along with study sample data from a patient dosed with commercially available Vicks 44. Using pcSFC and MS/MS, dextromethorphan was quantified in 96-well plates at a rate of approximately 10 min/plate with average intraday accuracy of 9% or better. Daily relative standard deviations (RSDs) were less than 10% for the 2.21 and 14.8 ng/mL quality control (QC) samples, while the RSDs were less than 15% at the 0.554 ng/mL QC level.

The identification and characterization of hydrazinyl urea-based antibacterial agents through combinatorial chemistry.

An effort to identify novel inhibitors of peptidoglycan synthesis with antibacterial activity resulted in the discovery of a series of biaryl urea-based antibacterial agents through isolation of a by-product from a mixture-based combinatorial library of semi-carbazones and subsequent parallel synthesis efforts. The compounds were shown to possess broad spectrum antibacterial activity against gram-positive drug resistant pathogens, and showed apparent specificity for disruption of the bacterial cell wall biosynthesis pathway.