Reducing the Impact of Metal Surfaces for Liquid Sampling Systems with a Silica-like CVD Coating

Stainless steel has become the standard for liquid sampling systems, especially for needles that may need to penetrate through a septum to gather the sample. While PEEK is a metal free alternative, it suffers from mechanical stability issues. Many studies have shown the impact that this metal surface has when utilizing it to transfer liquid samples. Some analytes, especially acidic or highly polar analytes will stick to stainless steel surfaces. This can lead to inaccurate quantitation and the risk of carryover from sample to sample. Additionally, metal can leach from the stainless steel into the liquid resulting in either adduct formation or, in some cases, oxidative reactions with analytes of interest. Here we show the impact that metal surfaces can have for certain analytes and a silica-like CVD coating that mitigates most issues for stainless steel while still maintaining the mechanical robustness one might expect out of a metal part.