Spinning cell device for fast standardization in laser ablation inductively coupled plasma spectrometry
A spinning cell device is described for fast and convenient standardization and analysis of constituents and isotopes in solid samples by laser ablation inductively coupled plasma (LA-ICP) spectrometry. The method and apparatus for performing the method require the sample under test and a standard to be spun during ablation allowing the quasi-simultaneous ablation of both materials. The aerosols resulting from the ablation of sample and standard are mixed in the ablation cell allowing quantification of the ablated metals by the method of standard addition or isotope dilution. The relative proportion of standard verses sample ablated can be changed by altering the trajectory of the laser beam. The ablated aerosol is swept into an inductively coupled plasma by a carrier gas and analyzed by mass spectrometry.
1. A dual matrix LA-ICP spectroscopic analysis system specifically adapted for performing a method of dual matrix LA-ICP analysis comprised of:
at least one ablation chamber housing which substantially encloses an ablation chamber;
an inductively coupled plasma ionization chamber fluidly connected to said ablation chamber;
wherein said ablation chamber housing is adapted for passage of a laser beam though the inner and outer surfaces of said ablation chamber housing;
wherein said ablation chamber housing includes at least two apertures to enable the entry and exit of an inert carrier gas into said inductively coupled plasma ionization chamber fluidly connected with said ablation chamber housing;
a revolvable sample receptacle adapted to secure a quantity of ablative material, wherein revolvable sample receptacle includes a designated area for a quantity of a sample under test and a designated area for a standard sample;
a motor operatively coupled to said revolvable sample receptacle and able to cause said sample receptacle to spin around an axis to produce a spinning sample under test; and wherein
a laser component which produces a laser beam, wherein said laser beam is directed at said spinning sample under test and wherein said laser can be configured to produce a static ablation trajectory that is in contact with said ablative material held within said spinning sample chamber for an ablation period.
2. The apparatus of claim 1 wherein said laser beam may be configured to selectively ablate only said sample under test during said ablation period.
3. The apparatus of claim 1 wherein said sample under test and said standard sample and said laser beam may configured to concurrently ablate said sample under test or said standard sample to produce said plurality of ablation products during said ablation period.
4. The apparatus of claim 1 which further includes a plurality of variably positioned trajectory settings, and wherein said laser and said sample under test is selectively positioned with respect to each other by a user.
5. The apparatus of claim 1 which further includes an analyte sensor wherein said plurality of ablation products include analyte sensor.
6. The apparatus of claim 1 which further includes a quantity of a sample under test having an unknown composition wherein said sample is comprised of ablative material.
7. The apparatus of claim 1 wherein said ablation chamber is connected to an inductively coupled plasma ionization chamber.
8. The apparatus of claim 1 wherein said inductively coupled plasma ionization chamber is operatively coupled to a mass spectrometer.
9. The apparatus of claim 1 wherein sample under test and said standard sample include a substantially similar matrix.
10. The apparatus of claim 1 wherein said substantially similar matrix that includes materials selected from a group consisting of: a glass, a known quantity of an isotopically enriched element, a known quantity of a rare earth element.
11. The apparatus of claim 1 wherein the ratio of flow rate to chamber volume is less than two times the rate of repetition of the application of the laser pulse.
12. The apparatus of claim 1 wherein said standard sample is a multi-element standard.
13. The apparatus of claim 1 wherein said chamber is constructed from polymethylmethacrylate.
14. A method for performing LA-ICP spectroscopic analysis specifically utilizing a dual matrix spinning sample apparatus which includes the steps of:
dispersing a known quantity of material in a first solid matrix to create a sample under test;
preparing a standard sample by dispersing a known amount of a material of known composition in a second solid matrix that is substantially similar to said first solid matrix;
placing said sample under test and said standard sample in a spinning sample holder of a dual matrix spinning sample apparatus;
selectively ablating said sample under test and said standard sample while said sample holder is spinning with a laser to produce a quantity of ablation products including analytes; and
transporting said ablation products to said inductively coupled plasma ionization chamber; and
measuring said analytes analyzing the ions generated by said inductively coupled plasma ionization chamber by an analytical technique compatible with inductively coupled plasma ionization.
15. The method of claim 14 which further includes the step of reusing a standard sample for multiple ablation periods.
16. The method claim 14 which further includes the step of repeating the step of selectively ablating said sample under test and said standard sample while said sample holder is spinning with a laser to produce a quantity of ablation products including analytes for multiple ablation periods.
17. The method of claim 14 which further includes the step of adjusting the trajectory of said laser with respect to the position of said sample under test after each successive ablation period.
18. The method of claim 14 which further includes the step of successively adding a known quantity of analyte to said ablation products of said sample under test within said ablation chamber to compensate for matrix effects.