title: Silicone sensing phase for detection of aromatic hydrocarbons in water employing near-infrared spectroscopy.
abstract: The use of silicone for detection of aromatic hydrocarbons in water using near-infrared spectroscopy is proposed. A sensing phase of poly(dimethylsiloxane) (PDMS) was prepared, and a rod of this material was adapted to a transflectance probe for measurements from 850 to 1800 nm. Deionized water samples contaminated separately with known amounts of benzene, toluene, ethylbenzene, and m-xylene were used for evaluation of the PDMS sensing phase, and measurements were made in a closed reactor with constant stirring. Equilibrium states were obtained after 90, 180, 360, and 405 min for benzene, toluene, ethylbenzene, and m-xylene, respectively. The PDMS sensing phase showed a reversible response, presenting linear response ranges up to 360, 290, 100, and 80 mg L(-1), with detection limits of 8.0, 7.0, 2.6, and 3.0 mg L(-1) for benzene, toluene, ethylbenzene, and m-xylene, respectively. Reference spectra obtained with different rods showed a relative standard deviation of 0.5%, indicating repeatability in the sensing phase preparation. A relative standard deviation of 6.7% was obtained for measurements performed with six different rods, using a 52 mg L(-1) toluene aqueous solution. The sensing phase was evaluated for identification of sources of contamination of water in simulated studies, employing Brazilian gasoline type A (without ethanol), gasoline type C (with 25% of anhydrous ethanol), and diesel fuel. Principal component analysis was able to classify the water in distinct groups, contaminated by gasoline A, gasoline C, or diesel fuel.
authors.affiliation: Departamento de Engenharia Química, UFPE, Av. Arthur de Sá, s/n, Cidade Universitária, 50740-521 Recife, Brazil.
authors.forename: Jackson S
authors.initials: JS
authors.lastname: Albuquerque
authors.forename: M Fernanda
authors.initials: MF
authors.lastname: Pimentel
authors.forename: Valdinete L
authors.initials: VL
authors.lastname: Silva
authors.forename: Ivo M
authors.initials: IM
authors.lastname: Raimundo
authors.forename: Jarbas J R
authors.initials: JJ
authors.lastname: Rohwedder
authors.forename: Celio
authors.initials: C
authors.lastname: Pasquini