Introducing the MSQ
______________________________________________________The Self-Cleaning Source: Cone Wash
The Self-Cleaning Source: Cone Wash
This section introduces the cone wash. Information on how and when to use
it is provided in the chapter
LC/MS and the Cone Wash
.
Introduction
The API source on the MSQ includes a self-cleaning solvent delivery
system (the cone wash). This makes the source extremely robust and
productive and greatly increases the number of samples that can be analyzed
before maintenance is required.
The orthogonal API probe serves to direct the LC eluent away from the inlet
orifice. However, under typical LC/MS conditions, both the ions and the
charged liquid droplets (containing involatile components) are deflected by
the electric field towards the inlet orifice. This effect leads to a gradual
buildup of involatile components and an associated loss in sensitivity with
time.
The self-cleaning API source delivers a constant, low flow of solvent to the
edge of the inlet orifice (see Figure 1-18). This prevents the buildup of
involatile components during LC/MS analysis with typical chromatographic
buffers (for example, phosphates and ion-pairing agents). This greatly
improves the quantitation precision of analysis without the need to
compromise the LC method, and more importantly, dramatically extends the
length of time possible for analysis.
Figure 1-18. Dispersion of involatile components from the inlet orifice
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