Very high throughput analysis of biological samples is becoming increasingly important in the field of high data content LC/MS(MS) based DMPK and Omics studies. There are several driving factors for this desire for speed: need for results as soon as possible e.g., lead candidate selection, FTIH clinical trials, forensic toxicology, hospital point of care for overdosing or due to the sheer numbers of samples requiring analysis, such as large cohort epidemiological studies or biobanks. LC/MS(MS) has become the technology of choice for DMPK, HT ADME, proteomics, metabolomics and lipidomics as it addresses the issues of ion suppression and isomer resolution thereby improving assay specificity, selectivity and sensitivity, allowing for analysis times in the 2-5 minutes range. The use of sub 2μm particle and solid core particle LC has facilitated fast high-resolution separations. The ability to access the true potential of these rapid LC/MS methodologies is, however, impeded by peak dispersion, both within the column (caused by frictional heating) and post column dispersion. Such peak dispersion results in increased peak widths and peak tailing leading to reduce overall peak capacity. Post column dispersion can be attributed to tubing connections between the column outlet and MS probe, as well connections within the electrospray probe itself. Here we describe the use of vacuum jacketed column technology with a novel column housing located on the source of the mass spectrometer to significantly reduce on and post column dispersion improving peak capacity and allowing analysis times as low as 30 seconds. VJC was applied to the DMPK, metabolomic and the lipidomic analysis of rat plasma & urine in early drug discovery studies resulting in improved, throughput, feature detection, spectral quality, database searching and assay sensitivity.
As an example; in the metabolomic analysis of human urine following acetaminophen dosing using a 60 second reversed-phase methodology the average peak widths improved from1.2 seconds to 0.6 seconds and the peak tailing factor reduced from 1.25 to 1.13 with the VJC system compared to UHPLC. The capacity increased from 65 (UHPLC) to (120 VJC) facilitating a 25% increase in feature detection. VJC also resulted a 20-120% increase MS peaks intensity, improving limits of detection. Reducing the LC gradient duration to 30 seconds gave peak widths of ca. 0.4 seconds and a peak capacity of 84, whilst still resolving all six acetaminophen metabolites in 7.2 seconds. Similar results were observed for the lipidomic analysis of rat plasma following the administration of gefitinib to the mouse VJC facilitated a 50% reduction in analysis time with no loss in feature detection.
