A chromium(III) oxide-coated steel wire prepared by arc ion plating for use in solid-phase microextraction of...

The authors introduce an arc ion plating method for the deposition of chromium oxide (Cr₂O₃) on a steel wire substrate, and its use as a coating for solid phase microextraction. The coating has a micro- and nano-scaled structure after annealing at 700 °C. It is found that Cr₂O₃ exhibits a good extraction capability for the aromatic hydrocarbons naphthalene, anthracene, fluorene, fluoranthene, and biphenyl. Following desorption by high temperature at 300 °C, the analytes were quantified by gas chromatography (GC). The limits of detection are in the range between 20 and 200 ng·L^-1, and calibration plots are linear within a wide range (0.2 to 400 μg·L^-1). The coating has excellent mechanical properties, with a hardness is as high as 31.7 GPa, and the adhesion strength between coating and substrate reaches 20.1 N (corresponding to the critical Hertzian contact stress of 10 GPa). This, along with the chemical and thermal stability of the Cr₂O₃ coating, endows the wire with a long operational life. It was used for at least 100 times without any obvious decline of extraction capability. Graphical abstract An arc ion plating method was introduced for the deposition of chromium oxide (Cr₂O₃) on a steel wire substrate, and its use as a coating for solid phase microextraction with high mechanical strength, stability, and long operational lifetime.