Liquid Chromatography-Mass Spectrometer (LC-MS) Flow Splitting and Sample Injection

Capillary Liquid chromatography/mass spectrometry (LC/MS) has been extensively used in life science for the analysis of peptides and proteins, especially in proteomics area.  Because it shows higher resolution and sensitivity over conventional LC.  Capillary LC utilizes columns with smaller inner diameters (< 0.5 mm) than conventional LC and flow rates from some few µL /min down to the nL/min or even pL/min range.   Smaller ID columns produce higher and narrower chromatographic peaks for a fixed amount of injected material as the same amount of analyte elutes at a higher concentration as well as a better separation efficiency.  The peak height is inversely proportional to the cross-sectional area of the column.  Meanwhile the lower solvent flow rate provides higher ionization and sampling efficiency allowing a higher percentage of analytes in the solution phase to be transmitted to the MS detector.  Combination of these effects provide better detection limit for mass spectrometry.