Please dry down sample in an evaporator, and place in a small microcentrifuge tube or similar. The last buffer the sample was in, before dry down, should be free of all salts and detergents such as Triton, SDS, and NP-40. Please clean up any samples not meeting these conditions on a C18, MCX, or cation exchange cartridge or column as appropriate. If necessary we can provide these columns and procedures, or can do it for you. While sample loading amount can vary an ideal loading sample amount per run should be near 1ug of material. Overloading should be avoided so as to not be wasteful with sample limited material and to prevent carryover and contamination of the LC setup. Contamination of mass spectrometers is a time intensive process and as such users will be charged extra if a thorough clean-out is required.