Adsorptive behavior and solid-phase microextraction of bare stainless steel sample loop in high performance liquid...

Area of Science:

• Analytical Chemistry
• Chromatography
• Environmental Science

Background:

• Stainless steel sample loops in High-Performance Liquid Chromatography (HPLC) were observed to adsorb various chemical compounds.
• The adsorptive mechanisms likely involve hydrophobic interactions, electron-rich element-metal interactions, and hydrogen bonding.
• Stainless steel's universal adsorption properties were confirmed.

Purpose of the Study:

• To investigate the adsorptive behaviors of stainless steel HPLC loops towards diverse organic compounds.
• To develop a novel, modification-free solid-phase microextraction (SPME) device using stainless steel.
• To establish an online SPME-HPLC method for the sensitive determination of polycyclic aromatic hydrocarbons (PAHs).

Main Methods:

• Studied adsorption of PAHs, halogenated benzenes, aniline derivatives, and other compounds on stainless steel loops.
• Developed a bare stainless steel loop as an in-tube SPME device, acting as both substrate and sorbent.
• Integrated the stainless steel loop SPME device with a six-port valve for an online SPME-HPLC system.

Main Results:

• The stainless steel loop demonstrated high extraction efficiency for PAHs, achieving enrichment factors of 651-834 without modification.
• The online SPME-HPLC method exhibited exceptionally low limits of detection (0.2-2 pg/mL) for PAHs.
• The method showed a wide linear range, good linearity (R² ≥ 0.9987), and excellent reproducibility (RSD ≤ 2.9%).

Conclusions:

• Bare stainless steel loops are effective, modification-free SPME devices with high strength and stability.
• The developed online SPME-HPLC method is highly sensitive and suitable for determining PAHs in environmental samples.
• The method achieved good recoveries (88.5%–93.8%) when applied to real environmental samples.