Material limitations for strong acids and bases

Strong acids and bases can negatively affect certain types of tubing, fittings, and component materials.

• Polyetheretherketone (PEEK) can be degraded in strong mineral acids, such as nitric and sulfuric acids, especially in the presence of halogens and halogen-containing chemicals.
• Silica capillaries and their polyimide coatings will start to degrade at pH 8 and greater.
• Stainless steel (SST) can be attacked by certain acids below pH 2.3, especially in the presence of halogens and halogen-containing chemicals and strong mineral acids like nitric and sulfuric acids. SST can also experience degradation when used with organic acids in organic solvents.
• Quartz flow cells can have degraded lifetimes in the presence of pH greater than 12.
• Polyimide used in the needle seat is stable in a pH range between 1 and 10 and in most organic solvents. It will degrade in the presence of concentrated mineral acids like sulfuric acid and in the presence of glacial acetic acid. It will be degraded by elevated basic condition, especially in the presence of ammonia or ammonium salts or acetates.