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The HP/Agilent Co-axial sheath-liquid flow CE-MS interface - 1
Smith and co-workers were the first to propose the co-axial delivery of a solvent to the end of the CE separation capillary as a terminal electrolyte reservoir [see references here].
Based on this work and an already available ESI-sprayer for LC-MS engineers at Hewlett-Packard developed a triple tube sprayer IF for CE-MS which was introduced to the market in 1995. A pictorial view of the HP/Agilent triple tube sprayer is given in the figure below. The arrows in the l.h.s. picture A, have following meanings: a. introduction of nebulising gas (N2), b. delivery of the sheath solvent, c. standard CE separation capillary (fused silica 365 µm o.d. and 25-100 µm i.d.) filled with BGE, d. SST spray needle (0.5 mm o.d., 0.4 mm i.d.)with electrical ground connection f, e. outer tube. The r.h.s. picture B shows the actual sprayer. The ribbed ring in the middle allows adjustment of the CE capillary in axial direction. The sprayer is placed in an enclosure (source) which is mounted in front of the MS inlet and thus allows to isolate the spray from environmental disturbances (see visualization on following pages).