Ir(COD)(NHC)Cl complexes provide significant insight into the catalytic processes underpinning SABRE hyperpolarization.

The application of liquid chromatography/mass spectrometry (LC/MS) followed by principal components analysis (PCA) has been successfully applied to the screening of rat urine following the administration of three candidate pharmaceuticals. With this methodology it was possible to differentiate the control samples from the dosed samples and to identify the components of the mass spectrum responsible for the separation. These data clearly show that LC/MS is a viable alternative, or complementary, technique to proton NMR for metabonomics applications in drug discovery and development.

The process of metabolite identification is essential to the drug discovery and development process; this is usually achieved by liquid chromatography/tandem mass spectrometry (LC/MS/MS) or a combination of liquid chromatography/mass spectrometry (LC/MS) and nuclear magnetic resonance (NMR) spectroscopy. Metabolite identification is, however, a time-consuming process requiring an experienced skilled scientist. Multivariate statistical analysis has been used in the field of metabonomics to elucidate differences in endogenous biological profiling due to a toxic effect or a disease state. In this paper we show how a combination of liquid chromatography/time-offlight mass spectrometry (LC/TOFMS) and multivariate statistical analysis can be used to detect drug metabolites in a biological fluid with no prior knowledge of the compound administered. Copyright # 2003 John Wiley & Sons, Ltd.As part of the drug discovery and development process it is essential to identify the pharmacokinetic and metabolic characteristics of the candidate pharmaceutical for selection and subsequent regulatory submissions. Failure to identify a drug metabolite can have very serious implications; for instance, the metabolite may actually be the active pharmacophore in the systemic system, or it could be a marker of toxicity. Therefore, the detection, identification and profiling of drug metabolites has become a central part of the drug discovery and development process.The process of metabolite detection and identification is typically a labor-intensive and time-consuming process. This process has been simplified by the use of radiolabeled compounds 1 and/or spectroscopic techniques such as mass spectrometry 2,3 and NMR spectroscopy. 4-6 These approaches have allowed drug metabolism scientists to detect/identify compounds at lower concentrations and with greater speed. Of these analytical techniques, LC/MS and LC/MS/MS have become the most popular and widely employed due to their speed, sensitivity and specificity. However, the use of these techniques for metabolite detection and identification still requires a trained and skilled scientist to produce highquality results.With the advent of combinatorial chemistry the number of compounds entering the drug discovery process for candidate evaluation has significantly increased. This has significantly increased the number of compounds submitted for metabolite profiling and identification. In an attempt to simplify and streamline this process, many analytical instrument manufacturers have developed software packages that allow the automated review of LC/MS data such that potential drug metabolites are identified.7 These software packages typically accomplish drug metabolite identification by calculating molecular masses of postulated drug metabolites through the addition of classical metabolic transitions to the mass of the administered compound, followed by the subsequent extraction of these masses from the TIC LC/MS data set, e.g., parent mass þ16 Da for hydroxylation, þ80 Da for sulfation, þ176...

The use of turbulent flow chromatography coupled to mass spectrometry (turbulent flow LC/MS) shows great potential for the rapid, direct analysis of pharmaceutical compounds in plasma and serum. The use of turbulent flow LC/MS has removed the need for any time-consuming sample preparation such as solid phase extraction, and allowed a total sample analysis time of approximately 2.5 min to be achieved. The coupling of a mass spectrometer with HPLC often not only results in greater sensitivity, but also the added specificity of the mass spectrometer reduces the need for complete resolution of the analyte from endogenous material in the matrix. This allows an on-line analysis approach to be used for the analysis of pharmaceuticals in biological matrices. Turbulent flow chromatography is achieved by the use of high flow rates and large particle size stationary phases. When coupled with mass spectrometric detection, the technique allows the direct analysis of plasma or serum samples with very rapid chromatography and, therefore, extremely high throughout. This work demonstrates the suitability of this technique for the validated analysis of biological samples for a novel isoquinoline pharmaceutical and offers some ideas on the future continued development, optimization and application of turbulent flow liquid chromatography.

A liquid chromatography tandem mass spectrometry (LC/MS/MS) method has been developed for the fast routine analysis of selected CYP450 probe substrate metabolites in microsomal incubations, with no sample pretreatment. This has allowed fast and simple assessment of the potential effects which drug candidates may or may not have on the metabolism of specific CYP450 probe substrates, providing information which can then be used to rationalize in vivo interaction studies required in the clinic. This methodology takes advantage of fast gradient chromatography as a generic means of sample separation and analysis. It provides high throughput analysis compared to conventional gradient HPLC, with no significant loss in chromatographic performance.