Preparation of a matrix layer for spectrometry

1. A method for preparation of a matrix layer for mass spectrometric analysis on a sample support using matrix assisted laser desorption/ionization, comprising detecting a light signal which has been at least partially attenuated by passing through the matrix layer, has been reflected by the matrix layer or has been scattered by the matrix layer, and the light signal is used to regulate the preparation of the matrix layer.

2. The method of claim 1 , wherein for the preparation of the matrix layer, a matrix solution, or a recrystallization solution, or dried matrix droplets in the form of a crystal “snow” are applied to the sample support.

3. The method of claim 2 , wherein the light signal is detected prior to, during, or after application of the matrix solution or recrystallization solution.

4. The method of claim 2 , wherein the matrix solution or recrystallization solution is applied in more than one cycle.

5. The method of claim 4 , wherein the light signal is used to regulate one of

the quantity of matrix solution or recrystallization solution applied,

the duration of application of the matrix solution or recrystallization solution,

the duration of the drying period,

the flow rate or temperature of a drying gas that is supplied,

the temperature of the sample support, and

the time sequence of the cycles.

6. The method of claim 4 , wherein, from the light signal of two cycles, the quantity of matrix applied or the change in the thickness of the matrix layer is determined.

7. The method of claim 2 , wherein the matrix solution is applied by pipetting, by pneumatic spraying, by vibration nebulizing or by nanospotting of droplets.

8. The method of claim 1 , wherein analyte molecules are applied to the sample support together with the matrix solution or recrystallization solution.

9. The method of claim 1 , wherein analyte molecules are located on the sample support.

10. The method of claim 9 , wherein the analyte molecules are located in a thin tissue section.

11. The method of claim 1 , wherein the light signal is detected with spatial resolution, or is integrated over the entire sample carrier or over part of the surface of the sample carrier.

12. The method of claim 1 , wherein the light from a light source is temporally modulated and the detected light signal is subjected to high pass filtering or to phase-selective amplification in order to minimize the effect of background illumination.

13. The method of claim 1 , wherein a reference light signal is additionally detected and the light signal and the reference light signal are used to examine the quality of the matrix layer or to regulate the preparation of the matrix layer.

14. A method for preparing a matrix layer on a sample support for a mass spectrometric analysis using matrix assisted laser desorption/ionization, comprising:

providing a command signal that controls a nebulizer which releases a mist of matrix solution droplets into a chamber;

a sample support onto which a tissue section is placed such that droplets of the matrix solution contact the tissue section;

a light source that emits a beam of light that passes through the sample support and back scatters off the tissue section;

a light detector that senses back scattered light and provides a detected light signal indicative thereof; and

a controller that receives the detected light signal and provides the command signal.

15. The method of claim 14 , where the controller controls the flow of a drying gas that dries the tissue section after analyte molecules have been extracted from the tissue section.

16. A system for preparing a matrix layer for mass spectrometry using matrix assisted laser desorption/ionization, comprising:

a nebulizer that receives a command signal and provides a mist of matrix solution droplets to a chamber;

a sample support that supports a tissue section such that the nebulized matrix solution falls onto the tissue section;

a light source that is located below the sample support and emits light which passes the sample Support and strikes the tissue section;

a light detector that is located below the sample support and detects light back scattered off the tissue section and provides a detected light signal indicative thereof;

a controller that receives the detected light signal and provides the command signal based upon the value of the detected light signal.

17. The system of claim 16 , where the light detector comprises a photodiode.

18. The system of claim 16 , where the light source comprises a light emitting diode.

19. The system of claim 18 , wherein the light emitting diode emits infrared light.

20. The system of claim 16 , wherein the controller provides a dryer command signal to a means for providing a drying gas to the tissue.