In the last decade, inductively coupled plasma triple quadrupole mass spectrometry (ICP-QQQ), also called inductively coupled plasma tandem mass spectrometry (ICP-MS/MS), has been a game changer in the world of trace analysis. Previously undetectable and unresolvable elements are now within analytical capabilities, opening doors in an array of application areas, from pharmaceuticals to environmental analysis.
In this discourse, we will take a look at what ICP-QQQ is, what it is used for and how it compares to inductively coupled plasma mass spectrometry (ICP-MS).
What is ICP-QQQ and how does it work?
Introduced in 2012, ICP-QQQ excites atoms and ions within mixed samples and then separates out the constituents according to their mass and charge characteristics to enable their identification and quantification. ICP-QQQ utilizes a triple quadrupole mass spectrometer to overcome challenges of spectral overlap and interferences seen when a single quadrupole (ICP-MS) is utilized, making it ideally suited to trace element analysis.
Interference from spectral overlap occurs when samples contain:
- Polyatomic ions
- Doubly charged ions
- Isobaric nucleotides
- Interference can also come from the sample matrix, solvent medium or even the plasma gas used in the analysis
Fig. 1: A schematic layout of the ICP-QQQ
Let’s take a look at what happens at the mass spectrometer
Fig.2: MS/MS capability of the ICP-QQQ
The facility for MS/MS means that scientists can have greater control over the ions entering the collision cell, and therefore over the origins of the reaction product ions observed at the detector. This enables spectral interferences to be reduced.
What is ICP-QQQ used for?
Fig. 3: Uses of ICP-QQQ
How does ICP-QQQ compare to ICP-MS?
ICP-MS, introduced in 1983, was the technique of choice for multi-element trace analysis for many years and offered low limits of detection. However, despite being an improvement on alternative techniques, spectral interferences were still a problem and proposed solutions required expensive instrumentation. ICP-QQQ changed this
Adapted from Technology Networks Infographics on ICP-QQQ.
Posted by Muyiwa Adebola
[email protected], www.aasnig.com