Delrin® Acetal Resin
Delrin has excellent chemical resistance to most organic solvents. This polymer's high tensile strength also permits superior threads that are very resistant to wear. Delrin is not suitable for use with acids, bases, or oxidizing agents.
PCTFE has excellent chemical resistivity. Only THF and a few halogenated solvents will react with it. This resilient polymer is excellent for fittings and sealing surfaces.
PEEK polymer has excellent chemical resistance to organic and inorganic liquids. Concentrated sulfuric acid and concentrated nitric acid are the only commonly used solvents that will chemically attack it. PEEK tubing is not recommended for use with methylene chloride, DMSO or THF due to a physical swelling effect. However, these chemicals do not adversely affect fittings. PEEK is a hard, yet slightly flexible polymer. It is excellent for nuts, ferrules, unions, valves, tubing, etc.
Polypropylene is a very soft polymer and is generally used in low-pressure applications. Polypropylene is excellent for aqueous solutions; however, it is attacked by chlorinated, aromatic, and some organic solvents.
Polyphenylene sulfide is relatively new to the analytical lab equipment market. PPS has excellent chemical resistance to most organic solvents at room temperature. However, it is not recommended for use with chlorinated solvents, inorganic acids or any solvent at elevated temperatures (see table above). PPS is a hard polymer offering excellent thread integrity.
These polymers are inert to virtually all chemicals used in HPLC. FEP is a good choice for tubing used from the reservoir to the pump and from the detector to a waste reservoir. PFA is a higher-purity member of this polymer family and can be used for tubing in sensitive applications as well as for molding low pressure fittings.
Tefzel is a member of the fluoropolymer family that is good for sealing surfaces. Tefzel is extremely resistant to chemical attack. However, some chlorinated chemicals will cause a physical swelling of Tefzel tubing. Tefzel tubing has slightly higher pressure capabilities compared to PTFE tubing, due to a higher tensile strength.