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Cleaving an Emitter Tip
Successful open capillary chromatography relies on properly made capillary connections. Junctions between fused
silica capillaries need clean, perpendicular cuts, or they will not seal properly. The capillaries have a protective
plastic coating and ordinary scoring devices, including diamond-tip pencils, can tear it. This leaves a jagged edge
that prevents the connections from sealing properly, and that can absorb sample components.
For detailed instructions for cleaving emitter tips, refer to the documentation for the fused silica cutter, located in
the Hardware Installation Kit.
NanoSpray
®
III Head
The NanoSpray
®
III head consists of a stainless steel microvolume union that is maintained at voltages from –2800
V to +3000 V, as well as a high-voltage rail and a nebulizer gas connection.
The high voltage charges the solution being sprayed, which lets the process occur without coated metal tips. The
charged solution is sprayed through a short piece of fused silica capillary or emitter tip.
Sample Solvent Composition
Solvents that are mixtures of water and organic modifiers offer higher sensitivity than pure water or pure organic
solvents alone. The ideal solvent is a 20:1 mixture of water and an organic solvent, together with a small amount
of acid or base to act as a modifier. Commonly used organic solvents include acetonitrile, methanol, propanol,
and commonly used modifiers include acetic acid, formic acid, ammonium formate, ammonium acetate, and
ammonium hydroxide.
Note:
Modifiers such as TEA (triethylamine), sodium phosphate, TFA (trifluoroacetic acid), and SDS (sodium
dodecyl sulfate) are not commonly used because their ion mixtures and cluster combinations complicate the
spectrum. They can also suppress the strength of the signal from the target ion.
Factors Affecting Optimization
The following factors affect NanoSpray
®
III head performance:
• Head position
Operator Guide
NanoSpray
®
Ion Source
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80 / 92
B
Tips for Working with the Ion
Source