Ammonium acetate can be a very useful additive for HPLC methods. With ammonium acetate, a near-neutral pH is obtained with this additive, so it is a popular choice for keeping most organic acids ionized, which is generally preferred for ANP methods. In addition, it is LC-MS compatible, in contrast to a near neutral pH phosphate buffer. However, it also is thought to adsorb to silica based stationary phase materials and therefore the column should thereafter be dedicated to methods using ammonium acetate.