WHAT IT IS
Tandem ICP-MS, also known as ICP-MS/MS, incorporates two mass filters in series, separated by a collision/reaction cell. The first mass filter selects ions based on their mass-to-charge ratio (m/z), while the second mass filter analyzes ions after interference removal or further mass selection. This design enhances sensitivity and selectivity, particularly for trace-level elements in complex matrices.
HOW IT WORK
Sample Introduction – A liquid sample is aerosolized via a nebulizer and introduced into an inductively coupled plasma, where the high-temperature plasma ionizes the sample atoms.
Ion Selection (MS1) – The first quadrupole mass filter (Q1) isolates ions of a specific m/zm/zm/z, ensuring only ions of interest enter the collision/reaction cell.
Interference Removal – In the collision/reaction cell, selected ions interact with gases (e.g., helium or hydrogen) that remove interferences through kinetic energy discrimination or chemical reactions.
Final Mass Analysis (MS2) – The second quadrupole mass filter (Q2) analyzes the ions after interference removal, providing precise and interference-free elemental and isotopic data.
Detection – The resulting ions are detected, and their intensities are measured to quantify elemental concentrations or isotopic ratios.
ADVANTAGES
Enhanced Interference Removal: The dual-mass-filtering design significantly reduces spectral interferences, enabling accurate analysis even in complex matrices.
Improved Sensitivity: Tandem ICP-MS provides high sensitivity, allowing detection of ultra-trace elements at parts-per-trillion (ppt) levels or lower.
Selective Analysis: The ability to isolate specific ions in MS1 ensures precise targeting of elements or isotopes of interest.
Wide Application Range: The technique is effective for various sample types, including environmental, biological, geological, and industrial materials.
Advanced Isotopic Analysis: Tandem ICP-MS is ideal for isotope ratio measurements, supporting studies in geochemistry, nuclear forensics, and environmental science.
LIMITATIONS OF TANDEM ICP-MS
Complexity and Cost: ICP-MS/MS systems are more expensive and require skilled operators due to their sophisticated design and operational demands.
Matrix Effects: While interference removal is improved, complex matrices can still introduce challenges, necessitating optimized sample preparation.
Longer Analysis Times: The additional mass-filtering step can increase the overall analysis time, especially for large sample sets.
Gas Requirements: The use of collision/reaction gases adds operational complexity and cost, as specific gases may be required for particular applications.
Instrument Footprint: Tandem ICP-MS instruments are larger and require more laboratory space compared to standard ICP-MS systems.
APPLICATIONS
Environmental Monitoring
Food Safety
Biomedical Research
Geochemistry
Nuclear Science
Pharmaceutical Quality Control