LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) is a powerful analytical technology that enables highly sensitive elemental and isotopic analysis to be performed directly on solid samples.
LA-ICP-MS begins with a laser beam focused on the sample surface to generate fine particles – a process known as Laser Ablation. The ablated particles are then transported to the secondary excitation source of the ICP-MS instrument for digestion and ionization of the sampled mass. The excited ions in the plasma torch are subsequently introduced to a mass spectrometer detector for both elemental and isotopic analysis.
![LA-ICP-MS Process](https://appliedspectra.com/wp-content/uploads/2015/06/LA-ICP-MS-Step-1-Image-large.jpg)
LA-ICP-MS diagram LA-ICP-MS Process – Laser ablation creates fine particles from the sample, which are then transported for rapid elemental and isotopic analysis.
![LA-ICP-MS Process](https://appliedspectra.com/wp-content/uploads/2015/06/LA-ICP-MS-Step-2-Image-large1.jpg)
Image of the laser ablation trench produced on three NIST glass standards (NIST 612, NIST 614 and NIST 616) during LA-ICP-MS trace element analysis (laser rastering speed = 10 mm/sec).
![Image of the 25 micron laser ablation in a 5x5 grid pattern](https://appliedspectra.com/wp-content/uploads/2015/06/LA-ICP-MS-Step-3-Image-large.jpg)
LA-ICP-MS craters Image of the 25 micron laser ablation craters in a 5 X 5 grid pattern on the glass surface and transient 27Al signal (20 sec laser pulses per sampled spot and 30 seconds between the spots)
![Comparison of the ablated particle size using nanosecond laser pulse](https://appliedspectra.com/wp-content/uploads/2015/06/LA-ICP-MS-Step-4-Image-large.jpg)
Comparison of the ablated particle size using nanosecond laser pulse and femtosecond laser pulse for a brass alloy sample (56% Cu & 44% Zn).
Benefits of LA-ICP-MS
LA-ICP-MS is one of the most exciting analytical technologies available because it can perform ultra-highly sensitive chemical analysis down to ppb (parts per billion) level — without any sample preparation.
Samples can be both conducting or non-conducting, and the analysis can be performed in the air without the need for a complex vacuum system. Results are available within seconds; therefore LA-ICP-MS delivers that fastest analysis speed of all analytical techniques with the limit of detection approaching ppb level.
The sample mass size required for LA-ICP-MS analysis is sub-microscale — picograms to femtograms. Traditional liquid nebulization approaches for ICP-MS require the removal of milligrams of sample mass in order to be effective.
When applied with optimized laser ablation conditions and ICP-MS data acquisition protocols, LA-ICP-MS allows versatile solid sampling schemes that include:
- Bulk analysis
- Local inclusion and defect analysis
- Depth profiling
- Elemental/isotope mapping
The two most commonly used laser-based methods are bulk analysis with a typical laser spot size of 100 ~ 350μm and microanalysis with the laser spot size as small as a few microns.
Femtosecond Laser Pulsing
The use of femtosecond laser pulsing represents the latest technical advance in LA-ICP-MS technology. It improves precision and accuracy, reduces the elemental/isotopic fractionation, and enhances the sensitivity of the measurements. Many researches have shown that femtosecond laser pulsing brings these benefits to LA-ICP-MS analysis:
- Non-thermal mass ablation such as Coulomb explosion and direct chemical bond breaking that represents the true chemistry of the sample and is conducive in reducing the elemental/isotopic fractionation.
- An ideal size distribution (20 ~ 200 nm) of the ablated particles that are readily transported to the ICP-MS plasma torch that result in the increased detection sensitivity.
- More consistent size distribution of the ablated particles that decrease the fluctuations in the transient ICP-MS signal and increase the measurement precision.
- Complete digestion of the transported particles and reduction of fractionation in the secondary excitation source of the ICP-MS instrument.
Applied Spectra’s J200 Femtosecond LA Instrument
![Comparison of the transient ICP-MS signal](https://appliedspectra.com/wp-content/uploads/2015/06/LA-ICP-MS-Step-5-Image-large1.png)
Comparison of the transient ICP-MS signal resulting from the femtosecond laser ablation (red) with respect to nanosecond laser ablation (black). The smaller and more consistent particle size distribution produces fewer fluctuations of the signal.
![j200-femtosecond](https://appliedspectra.com/wp-content/uploads/2015/06/j200-femtosecond-460px_295px.jpg)
Applied Spectra’s J200 series LA-ICP-MS instrument
Applied Spectra harnesses LIBS technology with its state-of-the-art elemental testing devices. We deliver solutions that are fast, reliable, precise and environmentally friendly. Our instruments are adaptable to a variety of environments, from field testing, to manufacturing floors, to laboratory settings. Contact ASI’s technical sales staff to learn more.
[1] R.E. Russo, X.L. Mao, H.C. Liu, J.H. Yoo, S.S. Mao: Appl. Phys. A 69 [Suppl.], S887–S894 (1999)