An inductively coupled plasma-time-of-flight mass spectrometer for elemental analysis. Part II: Direct current...

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Atomic Spectroscopy

Background:

• Traditional cylindrical lenses in ICP-TOFMS instruments present a trade-off between ion throughput and resolving power.
• An improved vacuum system was also integrated into the experimental setup.

Purpose of the Study:

• To evaluate the performance of an electrostatic quadrupole lens as a replacement for cylindrical lenses in ICP-TOFMS.
• To compare the ion-optical properties and detection capabilities of quadrupole and cylindrical lens systems.

Main Methods:

• Substitution of cylindrical lenses with an electrostatic quadrupole lens in an ICP-TOFMS instrument.
• Comparison of ion beam characteristics (flux, focus) using microchannel plate imaging.
• Implementation and evaluation of pulsed-ion injection technique with the quadrupole lens.

Main Results:

• The quadrupole lens eliminated the trade-off between ion throughput and resolving power seen with cylindrical lenses.
• Higher ion-beam flux and a slitlike focus were achieved with the quadrupole lens.
• Pulsed-ion injection significantly reduced noise, enabling detection of 0.5 femtomole of analyte in 1.4 ms.

Conclusions:

• The electrostatic quadrupole lens offers superior performance for ICP-TOFMS compared to cylindrical lenses.
• The combination of a quadrupole lens and pulsed-ion injection significantly improves signal-to-noise ratios and detection limits.
• This configuration shows potential for ICP-TOFMS to achieve detection limits competitive with quadrupole ICP-MS instruments.