plasma electrolytic deposition as a novel coating technique for preparation of solid-phase microextraction sorbents

Novel solid-phase microextraction coatings were prepared using cathodic and anodic plasma electrolytic deposition (ped) techniques on the titanium wire and used to measure the content of nerolidol in water and water distillate of bitter orange’ blossoms with gc-fid. ped is an attractive technique for metal surface modification, which can be used in cathodic ped configuration to coat the metal surface with carbon materials, while in the anodic configuration it causes surface etching and thus significantly increases surface porosity [1]. ped technique works based on contact glow discharge phenomena at atmospheric pressure. within electrolyte solution, plasma glow discharge produces inside the bubbles formed around the smaller electrode which is surrounded by a liquid electrolyte. in the anodic configuration, an adherent oxide such as alumina, silica, or titania film is produced [2]. in the cathodic configuration, nano-crystalline graphite films form in an electrolyte composed of ethanol and phosphate buffer [3]. in this research, in the cathodic mode, a dense carbonaceous layer was deposited on the ti rode. on the other hand, in anodic mode, the ti surface etched by the ped process and a highly porous surface was created. effective parameters in the extraction and desorption were investigated. the optimal conditions include microextraction of 50 ml of an aqueous solution containing 35% (w/v) nacl at 45 °c for 45 min using anodic coating followed by desorption using 50 μl hexane in an ultrasonic bath for 5 min. the developed method has a linear dynamic range of 1 to 1000 ng ml-1. the limit of detection (s/n=3) and the limit of quantification (s/n=10) of the developed method were 0.3 and 1 ng ml-1, respectively. the relative standard deviation of the method is less than 16%. the prepared adsorbent can be used many times due to its good mechanical stability. the developed method was used for the determination of nerolidol, as a product quality indicator, in the water distillate of bitter orange’s blossom. the developed method is a simple, convenient, sensitive and reproducible that can be used for the micro-extraction of volatile organic compounds in various aqueous and food matrices.