Laser Ablation with the icpTOF: Sensitive, Simultaneous Analysis of All Isotopes
Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is a well established technique for the direct elemental analysis of solid samples. Most LA-ICP mass spectrometers are based on quadrupole or scanning sector-field mass analyzers. With these “sequential” mass analyzers, isotopes in a user-defined list are sequentially measured one at a time in order to construct a mass spectrum. The time required to record an entire mass spectrum depends on the number of isotopes measured and is typically at least a few hundred milliseconds. In contrast, a time-of-flight (TOF) mass analyzer detects all isotopes simultaneously and can record a complete mass spectrum in tens of microseconds. For these reasons, TOF mass analyzers have long been proposed as a more suitable detector for LA applications, where signal transients can be as short as 1 or 2 milliseconds, arising from large individual particles or individual laser pulses. To date, though, commercial ICP-TOF mass spectrometers have suffered from poor sensitivity and other drawbacks.
This application note compares the performance of the TOFWERK icpTOF and a quadrupole-based ICP-MS as detectors for a laser ablation system. It is demonstrated that the icpTOF provides:
- Accurate results for even the shortest LA signals
- Fast, simultaneous measurement of all isotopes, ensuring that small sample features are never missed
- Lower limits of detection, better isotope ratio precision, and higher effective sensitivity for multi-element analysis than the QMS-based system