Ultra-fast HPLC MS analyses using active flow technology columns

• Active flow technology was used for high speed analyses of amino acids.
• Injection to injection cycle times were 24 s.
• AFT columns with 5 μm particles out-performed UHPLC columns with 1.9 μm particles.

A new development in HPLC–MS is presented, whereby the speed of the analysis is essentially equivalent to direct injection protocols applied in analyses using MS alone. The key to achieve these ultra-high through-put assays is the employment of a new design in HPLC columns referred to as active flow technology. Active flow technology HPLC columns enable the radial central portion of the flow to be sampled from the column and directed to a detector. This is the most efficient region of the solute migration, free from wall effects. In this study the internal diameter of the active technology column was 2.1 mm, the flow rate was 4.5 mL/min and 21% of this flow was sampled from the radial central region of the column; thus the flow to the MS detector was just 0.9 mL/min. The injection to injection cycle time was 24 s, comprising a 6 s period for the injector itself and an 18 s separation of 10 amino acids. The study presents details of the injection to injection reproducibility in this analysis, highlighting the substantial benefit of being able to undertake ultra-high through-put HPLC–MS.