Patent ID: 8460940

Claim:
A mass spectrometry method for analysing the presence or absence and/or quantity of at least one target analyte in a complex sample, wherein the complex sample: i) is or is derived from urine, blood, serum, or plasma; ii) comprises more than 50 different compounds; and iii) comprises more than 100 mM salt and/or urea, and wherein the target analyte is selected from the group consisting of mature hepcidin 25, truncated hepcidin isophorms and prohepcidin, the method comprising at least the following steps: a) providing a sample carrier suitable for mass spectrometry comprising a pre-applied microcrystalline matrix-assisted laser desorption/ionization (MALDI) matrix spot which is at least partially encompassed by a hydrophobic region, and wherein the microcrystalline MALDI matrix spot comprises crystals having predominantly a crystal size of ≦2 μm; b) applying a complex sample such that it becomes located on said microcrystalline MALDI matrix spot, wherein the complex sample; i) is or is derived from urine, blood, serum or plasma; ii) comprises more than 50 different compounds; and iii) comprises more than 100 mM salt and/or urea; c) washing said sample on said microcrystalline MALDI matrix spot with a washing solution; and d) analysing said sample for the presence or absence of at least one target analyte selected from the group consisting of mature hepcidin 25, truncated hepcidin isoforms and prohepcidin via mass spectrometry.