Molecular analysis of native tissue and whole oils by infrared laser mass spectrometry

We have employed infrared laser desorption ionization orthogonal time-of-flight mass spectrometry (IR-LDI-o-TOF-MS) to generate molecular ion profiles directly from native tissue and from whole oils. The method requires little sample preparation besides an eventual dissection of the areas of interest and drying of particularly water-rich samples. The lateral resolution of the analysis is on the order of the laser focal diameter, and in the third dimension, defined by the depth of material ejection, a few to 10 mu m per laser pulse. Various types of small molecules are readily detected from minute volumes of sample. Among these are carbohydrates, phospholipids, triglycerides, and flavonoids. Substantially different molecular profiles were recorded from different areas of a single strawberry seed.