Nanogram Per Gram Detection Limits in Elemental Determination by Femtosecond Laser Ablation and Ionization Mass Spectrometry

Widely used direct solids analysis mass spectrometry techniques, such as laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), glow discharge mass spectrometry (GDMS), and secondary ion mass spectrometry (SIMS), are capable of achieving detection limits in ng/g level. However, each technique has its own advantages and disadvantages. Laser ablation and ionization mass spectrometry (LAIMS) is a relatively new and powerful technique in direct solids analysis. To enhance its detection limits, we integrated a femtosecond laser and an ion counting system into LAIMS. Both conductive and nonconductive samples were analyzed in this study. The high-frequency femtosecond laser promotes atomization and ionization efficiency, and significantly reduces analysis time. The instrument combines data from time-to-digital converter (TDC) and analog-to-digital converter (ADC) modes, effectively expanding the dynamic range to 9 orders of magnitude with detection limits in ng/g level. The sum of all the spectral interference signals only accounts for 1 × 10^-5 of the total ion current. These advancements underscore the potential of LAIMS as a versatile tool for direct solids analysis, positioning it as a competitive alternative to LA-ICPMS, GDMS, and SIMS.