Osaka Soda CAPCELL PAK C18 ACR was synthesized through a modified polymer-coating technique, and intended to show an outstanding durability under an acidic mobile phase. Its performance was proven in the evaluation method originally designed for acidic resistance. ACR stands for Acidic Resistance. This packing material realizes not only basic resistance but also outstanding acidic resistance generated by further improvements to the polymer coating technology used for CAPCELL PAK.