Journal of Chromatography A, 1164 (2007) 18–24 Preparation and application of NiTi alloy coated with ZrO 2 as a new fiber for solid-phase microextraction Dilma Budziak, Edmar Martendal, Eduardo Carasek ∗ Departamento de Qu´ ımica, Universidade Federal de Santa Catarina, Florian´ opolis, SC 88040-900, Brazil Received 18 April 2007; received in revised form 27 June 2007; accepted 2 July 2007 Available online 5 July 2007 Abstract In this study a NiTi alloy was applied as an SPME support due to its superelasticity and shape memory properties. This new metallic support was coated with ZrO 2 by electrodeposition using chronoamperometry. It was then evaluated for extraction of three classes of compounds from gaseous samples: alcohols, BTEX and trihalomethanes (THM). For the optimization of the parameters affecting the extraction efficiency of the target compounds, the univariate approach was used. Five fibers were electrodeposited to evaluate the reproducibility of the coating procedure, resulting in a relative standard deviation lower than 11.9%. The repeatability for one fiber (n = 6) was lower than 8.5%. The detection limits were lower than 28.1, 20.8 and 0.18 gL -1 for alcohols, BTEX and THM, respectively, and the correlation coefficients were higher than 0.996. Taking into account the amount extracted per unit volume, the NiTi–ZrO 2 fiber showed a better extraction profile in comparison with the commercial fibers 7 m PDMS, 85 m PA and 30–50 m DVB/CAR/PDMS. The new SPME fiber has a lifetime of over 300 extractions. Thus, it is a promising alternative for low-cost analysis, as it is robust, and easily and inexpensively prepared. © 2007 Elsevier B.V. All rights reserved. Keywords: NiTi; ZrO 2 ; Electrodeposition; Gas chromatography; Volatile organic compounds 1. Introduction Solid-phase microextraction (SPME), first introduced by the research group of Arthur and Pawliszyn [1], is widely accepted and is the subject of an ever increasing number of publica- tions. It offers a solution for several sampling problems. This technique is simple, relatively fast, solvent-free, inexpensive, easily automated, and safe and it has been successfully applied in both headspace sampling and directly in aqueous samples, with excellent sensitivity and good selectivity [2]. SPME represents an important advance in the extraction effi- ciency of several organic pollutants at trace levels from different matrices, such as foodstuff [3–5], environmental [6–8] and bio- logical samples [9–11]. Fused silica has been widely and successfully used as a sup- port for SPME coatings, however, it has the disadvantage of being fragile. The use of metal wires as SPME supports with high mechanical stability makes this technique more robust for ∗ Corresponding author. Fax: +55 48 33316845. E-mail address: carasek@qmc.ufsc.br (E. Carasek). routine analysis [12]. Several studies have been developed using different material coatings over the traditional fused silica sup- port, such as platinum [2,13,14], anodized aluminum [15], gold [16,17], stainless steel [12,18,19] and copper [20] wires. Recently, a new generation of SPME fibers was commer- cially introduced by Supelco, which use an NiTi alloy as the support. This new fiber is referred to as a super elastic fiber assembly [21]. The approximately equiatomic NiTi alloy, com- mercially known as NiTinol, has an interesting characteristic of shape memory. This, and other characteristics of this material, such as, superelasticity, high stability with regard to the exter- nal environment, high biocompatibility, excellent durability and resistance to corrosion, are highly desirable [22]. Mainly due to its biocompatibility and shape memory, this NiTi alloy has been widely used in the preparation of endovascular prosthesis for minimally evasive surgeries in the treatment of aneurisms [23]. Electrodeposition offers important advantages such as a rigid control of the film thickness formed, uniformity and deposition rate. This method is especially attractive due to the possibil- ity of deposition onto complex shape substrates, high purity of deposits, low-temperature processing and low-cost equipment [24]. 0021-9673/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2007.07.001