High dead volume pumps: delay time reduction by short-term low-ratio split flow in LC/MS applications.

The aim of our work was to develop a low-cost, simple and reliable solution to reduce LC/MS analysis time by compensating for limitations inherent to high dead volume standard HPLC pumps. In our approach, we utilized a temporary (sub-1 min) low ratio flow split (approximately 1:10) at 5 mL/min pump flow before the column. During this short period, 90% of the entire pump flow is delivered to waste and used for fast pump/system equilibration. Although full-time flow splitting is widely used in capillary/nano applications (usually with high split ratios in the hundreds or thousands), to our knowledge, this is the first time that short-term low-ratio flow splitting has been used in conventional LC/MS applications.