Enhanced Performance Test Mix for High-Throughput LC/MS Analysis of Pharmaceutical Compounds

Abstract

LC/MS is being used for the routine analysis of small molecules in both the discovery and development stages within the pharmaceutical industry. In drug discovery, LC/MS is relied upon to confirm the identity and assess the purity of chemical entities. To ensure the quality of LC/MS analysis, it is important that the LC/MS system is operating within defined performance criteria. Performance monitoring of the system with a standard compound mix offers many advantages over other alternatives, since it monitors the LC/MS system as an integrated unit under the same working conditions as those used for the analysis of samples. It is also a convenient approach, because the test mix can be injected as part of the automated sequence. Use of a test mix for similar purposes has been described previously (Tang, L.; Fitch, W. L.; Alexander, M. S.; Dolan, J. W. Anal. Chem. 2000, 72, 5211-5218). To monitor the performance of ArQule's LC/MS operation (with UV and ELS detection) in greater detail, a set of eight compounds was selected from a collection of 137 commercially available "druglike" compounds. The compounds are generally stable and compliant with the rule-of-five criteria. This enhanced mix has a balanced selection of pKa values and covers the typical range of hydrophobicity and molecular masses of pharmaceutical compounds. Moreover, the selected compounds can generally be ionized using ESI and APCI modes with positive and negative polarity. The test mix can be used under formic acid or ammonium hydroxide conditions and with methanol or acetonitrile as an organic modifier. Performance monitoring with the enhanced mix is demonstrated with respect to ionization and mass measurement, as well as changes in gradient profile, flow rate, buffer pH, and ionic strength.

Internal Standard Capillary Electrophoresis as a High-Throughput Method for pKaDetermination in Drug Discovery and Development

“…Pharmaceutical companies synthesize a large number of potential drugs and chemical precursors in relatively short periods. , Those that are those most suitable are then selected for further testing and development. As a consequence, high-throughput screening for rapid evaluation of compounds is needed as soon as they are available from synthesis. − …”

On-Column Solvent Exchange for Purified Preparative Fractions

“…Evaluation of an experimental Waters hydrophobic–lipophilic balanced copolymer (HLB 30 μm) column demonstrated performance similar to the X-Bridge column when measuring loadability and retention capacity for flavone and cortisone. However, significant breakthrough was observed for many other test compounds 11 (e.g., metronidazole, amitriptyline hydrochloride, and labetalol; 25 mg each in acetonitrile:water [1:1] 11 mL). Additionally, a significant volume of water was collected with the target compound during elution, extending the evaporation time required.…”

“…However, significant breakthrough was observed for many other test compounds 11 (e.g., metronidazole, amitriptyline hydrochloride, and labetalol; 25 mg each in acetonitrile:water [1:1] 11 mL). Additionally, a significant volume of water was collected with the target compound during elution, extending the evaporation time required.…”

The use of partially porous particle columns for the routine, generic analysis of biological samples for pharmacokinetic studies in drug discovery by reversed-phase ultra-high performance liquid chromatography–tandem mass spectrometry

“…The structures, molecular weights and calculated log P values are shown in Table 1. These "druglike" test mix components were carefully chosen from other test mixes found in literatures [35,36] (Labetalol and Reserpine), and from in-house experience (bromo-guanosine and SB243213A) to cover a range of analytical-related physicochemical properties of most pharmaceutical compounds, such us hydrophobicity and molecular weight. Test mix concentrations were optimised to obtain comparable MRM responses in positive and negative modes for all four compounds and within the detection linearity range for each compound when using an API4000 mass spectrometer fitted with either turbo-ionspray or atmospheric pressure chemical ionisation probes.…”