When To Use PEEK Tubing Over Stainless Steel Tubing in HPLC
PEEK tubing has advantages over stainless steel tubing when plumbing your HPLC system, but it also has its limitations. PEEK is a high-performance engineered polymer with mechanical- and chemical-resistance properties that absorb high temperatures, making it highly resistant to thermal degradation. Its distinct materials make it inert to most solvents and give it a smooth internal surface that improves sample bands’ resolution.
PEEK Tubing Is Less Expensive
PEEK tubing is a popular choice for lab technicians because it is relatively inexpensive compared to SS tubing and can easily be cut in the lab when using the appropriate tubing cutter. Chrom Tech’s polymer tubing cutter provides a clean, burr-free, 90-degree cut for your 1/16” OD or 1/8” OD tubing.
On the other hand, stainless steel tubing is quite difficult to get a burr-free cut of in the lab; therefore, we recommend purchasing pre-cut stainless steel tubing.
It is less expensive to buy a large roll of PEEK tubing; from there, you can cut the individual lengths that are needed to re-plumb your HPLC System. When re-plumbing with stainless steel, we would recommend you purchase the pre-cut individual lengths rather than buy a large length to cut in the lab (however, some people still do this). To decide for yourself if it’s worth cutting stainless steel tubing in the lab, read our blog To-Cut-Or-Not-To-Cut.
PEEK Tubing Is Bioinert
In some bioseparation applications, scientists need all their HPLC products in the flow path to be Bioinert; therefore, PEEK tubing is the obvious choice.
If It’s Less Expensive and Easier To Cut, Why Wouldn’t We Always Use PEEK Over Stainless Steel Tubing?
Stainless steel tubing still has its place in the HPLC system, and it is quite popular—especially as our industry trends to ultra-high pressure HPLC Systems (UHPLC). Although the maximum pressure rating for tubing is always limited by the choice of fittings and connections used in the system’s plumbing, stainless steel tubing has significantly higher pressure ratings over PEEK. PEEK tubing can typically hold (if fitting connections are made properly) up to about 5,000 PSI, while Stainless Steel tubing (if appropriate fittings are selected and connections are made properly) can hold upwards of 20,000 PSI.
Although PEEK tubing is inert to most solvents, it is not recommended to use with dichloromethane, THF, and DMSO, as these solvents may cause swelling in PEEK tubing. Also, concentrated nitric and sulphuric acid will attack PEEK.
With its introduction into the marketplace, PEEK Tubing has become a popular replacement for stainless steel tubing for many applications’ fluidic needs. Please contact Chrom Tech to discuss which HPLC products to use in your lab.