An apparatus for preparing samples for measurement by x-ray fluorescence spectrometry. A plate has one or more holes passing through the plate. The holes are covered by a film on one side of the plate. The holes are less than 500 micrometers across in one dimension where the film covers the holes. The film is translucent to x-rays.
1. An apparatus for preparing one or more samples for measurement by xray fluorescence spectrometry, comprising a plate having at least one hole penetrating said plate; a film covering said hole, said film being at least 5% translucent to 2,300 eV X-rays oriented normal to said film; and said hole being less than about 500 micrometers in, at least one dimension parallel to said film at the location where said hole adjoins said film.
2. The apparatus of claim 1 , wherein said hole has an included angle of less than about 45 degrees.
3. The apparatus of claim 2 , wherein the area of said hole is less than about 0.005 square centimeters at the location where said hole adjoins said film.
4. The apparatus of claim 3 , wherein the interface of said hole and said plate have an RMS roughness of less than about 20 micrometers.
5. The apparatus of claim 4 , wherein said film is deformed from the plane defined by the portion of said hole that adjoins said film, said deformed being at least 100 nanometers.
6. The apparatus of claim 5 , wherein the cross sectional area of said hole is greater at the location wherein said hole adjoins said film than the cross sectional area of the narrowest portion of said hole.
7. The apparatus of claim 1 , further comprising an x-ray fluorescence spectrometer, said x-ray fluorescence spectrometer being capable of producing an x-ray excitation beam, said x-ray excitation beam having it beam cross sectional area containing at least 80% of the x-ray flux of said x-ray excitation beam at the location where said x-ray excitation beam is incident on said sample; said sample having a sample cross sectional area at the location where said x-ray excitation beam is incident on said sample; said beam cross sectional area being within a factor of 100 of the area of said sample cross sectional area.
8. The apparatus of claim 1 , wherein said film is substantially free of the at least one chemical element selected from the set of chemical elements having an x-ray fluorescence emission peak or an x-ray fluorescence escape peak having an energy of between 1.9 KeV and 3 KeV.
9. The apparatus of claim 1 , wherein the surface of said hole has no surface features that is greater than 200 microns in the dimension normal to the inside face of said hole.
10. A method for preparing a sample for measurement by x-ray fluorescence spectrometry, comprising providing at least, a portion of the sample located in a hole in a plate, the hole being covered by a film, the film being at least 5% translucent to 2,300 eV X-rays oriented normal to the film; and the hole being less than about 500 micrometers in at least one dimension parallel to the film at the location where the plate adjoins the film.
11. The method of claim 10 , wherein the at least a portion of the sample is concentrated by a factor of at least five.
12. The method of claim 10 , wherein the area of the hole is less than about 0.005 square centimeters at the location where the plate adjoins the film.
13. The method of claim 10 , wherein the at least a portion of the sample deforms the film defined by the portion of the plate that adjoins the film by at least 100 nanometers.
14. The method of claim 10 , wherein the cross sectional area of the hole is greater at the location wherein the plate adjoins the film than the cross sectional area of the narrowest portion of the hole.
15. The method of claim 10 , wherein the x-ray fluorescence spectrometer is capable of producing an x-ray excitation beam, the x-ray excitation beam having a beam cross sectional area containing at least 80% of the x-ray flux of the x-ray excitation beam at the location where the x-ray excitation beam is incident on the at least a portion of the sample; the at least a portion of the sample having a sample cross sectional area at the location where the x-ray excitation beam is incident on the at least a portion of the sample; the beam cross sectional area being within a factor of 100 of the area of the sample cross sectional area.
16. The method of claim 10 , wherein the film is substantially free of the at least one chemical element selected from the set of chemical elements having an x-ray fluorescence emission peak or an xray fluorescence escape peak having an energy of between 1.9 KeV and 3 KeV.
17. The method of claim 10 , wherein the surface of the hole has no surface features that is greater than 200 microns in the dimension normal to the inside surface of the hole.
18. The methods of claim 11 , wherein the at least a portion of the sample is obtained from a sample, wherein the sample comprises at least one solute selected from the set of proteins and nucleic acids, wherein the mass of the sulfur or phosphorus or a combination of sulfur and phosphorus in the protein or nucleic acid is preferably between 50 femtograms and 1microgram in a volume of between two microliters and 2 milliters prior to the sample being concentrated.
19. The method of claim 10 , further comprising measuring the sample using an x-ray fluorescence spectrometer.