Hydrofluoric Acid Etched Stainless Steel Wire for Solid-Phase Microextraction

Abstract

Stainless steel wire has been widely used as the substrate of solid-phase microextraction (SPME) fibers to overcome the shortcomings of conventional silica fibers such as fragility, by many researchers. However, in previous reports various sorbent coatings are always required in conjunction with the stainless steel wire for SPME. In this work, we report the bare stainless steel wire for SPME without the need for any additional coatings taking advantage of its high mechanical and thermal stability. To evaluate the performance of stainless steel wire for SPME, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, chlorobenzene, n-propylbenzene, aniline, phenol, n-hexane, n-octane, n-decane, n-undecane, n-dodecane, chloroform, trichloroethylene, n-octanol, and butanol were tested as analytes. Although the stainless steel wire had almost no extraction capability toward the tested analytes before etching, it did exhibit high affinity to the tested PAHs after etching with hydrofluoric acid. The etched stainless steel wire gave a much bigger enhancement factor (2541-3981) for the PAHs than the other analytes studied (< or = 515). Etching with hydrofluoric acid produced a porous and flower-like structure with Fe(2)O(3), FeF(3), Cr(2)O(3), and CrF(2) on the surface of the stainless steel wire, giving high affinity to the PAHs due to cation-pi interaction. On the basis of the high selectivity of the etched stainless steel wire for PAHs, a new SPME method was developed for gas chromatography with flame ionization detection to determine PAHs with the detection limits of 0.24-0.63 microg L(-1). The precision for six replicate extractions using one SPME fiber ranged from 2.9% to 5.3%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 4.3-8.8%. One etched stainless steel wire can stand over 250 cycles of SPME without significant loss of extraction efficiency. The developed etched stainless steel wire is very stable, highly selective, and reproducible for the SPME of PAHs.

Development of Novel Solid-Phase Microextraction Fibers

“…Subcellular analysis was realized in nucleus and cytoplasm. SSW, which is widely used as supporting substrates of SPME fibers nowadays, was simply etched with hydrofluoric acid to be used as a SPME fiber [171]. The fiber possessed a porous and flower-like structure with Fe 2 O 3 , FeF 3 , Cr 2 O 3 , and CrF 2 on the surface (Fig.…”

Recent developments in solid-phase microextraction for on-site sampling and sample preparation

“…However, the metal may catalyze the degradation of the coated polymers during thermal desorption [7]. A new development in this SPME type applies hydrofluoric acidetched stainless steel wire as extraction phase without any additional coatings [48]. The etching process produces a porous, flower-like structure with metal oxides and metal fluoride on the surface of the stainless-steel wire, which has high affinity to polyaromatic hydrocarbons (PAHs).…”

Graphenized pencil lead fiber: Facile preparation and application in solid-phase microextraction

“…To overcome these disadvantages, a number of lab-made coatings have been developed for SPME, such as nanomaterials [4], molecularly imprinted polymers [5], ionic liquids [6], mesoporous silica [7], etc. Besides, coating-free fibers have also been developed to eliminate the problems associated with coating stability, such as pencil lead [8][9][10], metal wires [11], and carbon monolith [12]. Despite that, the performance of these fibers still needs to be further improved and new fibers are highly desired.…”