Buffers and mobile phase solvents used in LC-MS applications should ideally only contain volatile components. The most common volatile salts for buffering in LC-MS mobile phases are ammonium formate and ammonium acetate. Here, adjustments in pH are performed with volatile acids and bases such as formic acid and ammonia. Usually, some non-volatile components get introduced during assays of biological samples with sample injections. Mass spectrometer instruments can handle small amounts of these non-volatile components with routine cleaning and maintenance.