Comparison of electrospray and inductively coupled plasma sources for elemental analysis with mass spectrometric detection

Both the qualitative and quantitative aspects of electrospray (ES) and ICP sources were investigated using the same mass spectrometer (originally a VG PlasmaQuad I instrument). While it is well established that ICP-MS is a powerful tool for elemental analysis, electrospray ES-MS has recently become popular as a promising elemental analysis technique that can complement the detection capabilities of ICP-MS. The in-house constructed ES source efficiently produced the bare singly charged metal ion and the optimum ES source conditions varied depending on the charge reduction required to attain the singly charged state. The day-to-day signal reproducibility was excellent (5% RSD), and the removal of the photon stop increased ion transport to the detector. A comparison of the figures of merit for Rb, Cs, Ba, V, Cr, Ni, Co, Cu, Zn and U showed that the detection limits obtained by ES-MS (ng ml(-1)) are only 2-3 orders of magnitude higher than those found using the ICP source. Additionally, Ca was determined in NIST SRM 1643c (Trace Elements in Water) by ES-MS.