Proper sample preparation is crucial for obtaining good results with mass spectrometry. There are several general factors namely, purity, concentration, salt content, solvent used and the nature of compound. Below, please find the guidelines to different services:
Call us at (617) 384-9585 if you have any questions regarding sample preparation. As a rule of thumb, avoid the use of detergents (especially non-ionic detergents), nonvolatile salts, TFA (>0.10%) and other additives. A table of salts and buffers which are incompatible with mass spectrometry and their levels is downloadable below. If salts must be used, stick with a volatile salt like 10 mM ammonium acetate. If you have salts/TFA in your hydrophobic sample, a customized LC-MS method can be developed that diverts salts to waste for the first 2 minutes. We recommend a ZiptipTM cleanup for hydrophobic samples prior to analysis, if no LC step is involved. Some samples like oligonucleotides are particularly susceptible to salt interference and must be thoroughly desalted prior to analysis with techniques like MALDI-TOF MS.
It is recommended that you submit the samples in autosampler vials with a screw top (PTFE septum). This is especially true if you have volatile solvents in your sample! Snap top vials can also be used for samples contained in less volatile samples such as water! If you have chloroform or acetonitrile in your sample, please use glass vials and glass inserts (if required for lower volume). This is because plastics will leech out plasticizers directly into your sample when solvents such as chloroform are used. Finally, remember that if you have non-volatile salts or TFA, you want to separate your analyte from them using HPLC for good sensitivity. For GC-MS please consult with Jennifer Wang about autosampler vials to minimize background contamination. Plastic vials should not be used when any organic solvents are present.