When performing electrospray ionization mass spectrometry, reducing chromatographic flow rates can improve sampling efficiency and therefore increase sensitivity. When operating in the nanoflow regime (50-500 nL/min) very high sampling efficiencies are possible. However, nanoflow ionization can require significant user expertise and advanced tuning to get best performance. Significant research was done to determine whether most source parameters could be optimized and locked in, to take out most of the user interactions. Using Design of Experiments, x,y,z positioning, tip protrusion, ionization voltage, nebulization gas and other parameters were examined. Spray electrodes were developed for maximal robustness. This led to the development of the OptiFlow® Source, a single source that would cover the full spectrum of low flow rates for high sensitivity LC-MS analysis.
Performance was evaluated relative to a highly tuned NanoSpray® Source III on both a TripleTOF® 6600+ system and a QTRAP® 6500+ system. Equivalent chromatographic performance was observed comparing peak width and area. 30 day testing was performed to check spray electrode robustness and minimal change in backpressure was observed. The SWATH® Acquisition Performance kit was run with both sources and very equivalent performance was again observed, within 5% in IDA and SWATH acquisition modes. Next, plug and play cartridge based nanoflow columns will be tested with different phases.