Laser desorption lamp ionization source for ion trap mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Spectroscopy

Background:

• Laser desorption mass spectrometry (LDMS) is a powerful technique for analyzing non-volatile compounds.
• Existing LDMS methods can be limited by sensitivity and ionization efficiency.
• Ion trap mass spectrometers (ITMS) offer advantages in ion storage and detection.

Purpose of the Study:

• To construct and characterize a novel two-step laser desorption lamp ionization source coupled to an ion trap mass spectrometer (LDLI-ITMS).
• To evaluate the sensitivity and performance of the LDLI-ITMS for analyzing various compounds.
• To compare the LDLI-ITMS with existing laser desorption mass spectrometry techniques.

Main Methods:

• A two-step ionization process involving pulsed infrared (IR) laser desorption and vacuum ultraviolet (VUV) lamp ionization.
• Utilizing an Nd:YAG laser (1064 nm) for desorption and a xenon-filled VUV lamp (148 nm) for ionization.
• Employing a modified three-dimensional quadrupole ion trap mass spectrometer for ion storage and detection.

Main Results:

• The LDLI-ITMS system demonstrated a limit of detection of 1.5 pmol for coronene molecules.
• This represents a two-order of magnitude improvement in sensitivity compared to fluorine excimer laser-based LDMS.
• Mass spectra of standard aromatic compounds showed dominant parent ions, indicating efficient ionization.
• The instrument showed capability for detecting inorganic compounds by increasing IR laser power.

Conclusions:

• The developed LDLI-ITMS is a highly sensitive and versatile analytical tool.
• The two-step ionization approach significantly enhances detection limits for molecular analysis.
• This technique holds promise for the analysis of complex organic and inorganic samples.