Inductively coupled plasma mass spectrometry (ICP-MS) is a technique used for elemental analysis and identifying unknown compounds. This technique has the capacity to detect most elements in the periodic table at levels as low as nanograms per liter.
What is Inductively Coupled Plasma?
ICP instruments utilize a plasma torch as an ionization source that works to separate the constituent elements in a sample and convert them into ions. The plasma is created by an RF generator that is fed a plasma gas, usually Argon, through the torch.
Importance of Environmental Analysis
There is a range of factors that drive environmental analyses, specifically the requirements for determining elements at low concentrations and their bio-availability. Contamination and sample pre-treatment must be minimized to preserve the sample. As the costs of environmental analysis increase, quick and accurate testing methods that can capture data on multiple analytes becomes a top priority. 1
Benefits of using ICP-MS For Environmental Analysis
ICP-MS uses an ICP as an ion source for a mass spectrometer. The sample is introduced to the mass spectrometer as a solution, through a sample introduction system, starting with a nebulizer, transforming the solution into an aerosol. The aerosol is then introduced into a spray chamber that removes the large droplets that would usually overload the plasma.
A fine aerosol then vacates the spray chamber and is placed into the center of the plasma allowing for vaporization, atomization, and ionization to take place in a sequence.
In standard ICP-MS instruments, the severance of ions is carried out via a sector-field (SF) quadrupole (Q) or time-of-flight (TOF) mass spectrometer. The quadrupole is beneficial for continuously and rapidly monitoring ions sequentially. This is because the ions that have a stable path in the radio-frequency (RF) field from opposite rods of the device travel through at a specific time.
Conversely, discrete packets of ions that are extracted from the ICP are brought into the TOF mass spectrometer. Inside the mass spectrometer, ions that are separated in accordance with their flight time in a field-free region, all arrive at the detector in order but far quicker than quadrupole spectrometers can scan a mass spectrum.
Before the widespread use of ICP-MS, environmental analysis was generally carried out using flame or graphite furnace atomic absorption spectrophotometry (AAS). This technique only allowed for the identification of one ion element at a time.
Inductively coupled plasma optical emission spectrometry (ICP-OES) can also be used for multi elemental analysis. However, this technique did does not offer the detection limits required for ultra-trace analysis.
Importance of Tuning Solutions for ICP-MS
It is critically important for ICP-MS systems to be properly calibrated so they can carry out highly accurate elemental analyses. They must be tuned regularly to achieve precise results. Tuning solutions can be used to setup and calibrate the mass filter and lenses of spectrometers, optimizing overall performance of the instrument.
Learn More in Our Recent Webinar
ICP-MS is regularly used to analyze environmental samples such as wastewater. Most approaches are based upon the 6020 or 200.8 techniques created by the U.S. Environmental Protection Agency (EPA).
In this webinar, those techniques serve as a foundation for exploring the frequently occurring issues that relate to obtaining accurate ICP-MS data for environmental analysis, such as: 1) application of interference check solutions, 2) sample preparation artifacts, and 3) the stability and compatibility of ‘problem’ elements.
To find out more view our webinar recording today.
References
https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/full/10.1002/mas.2025