title: Ion pair-based dispersive liquid-liquid microextraction for gold determination at ppb level in solid samples after ultrasound-assisted extraction and in waters by electrothermal-atomic absorption spectrometry.
abstract: A new methodology was developed for the determination of ultratrace levels of gold in water samples, soils and river sediments. Dispersive liquid-liquid microextraction was used to preconcentrate the ion pair formed between AuCl(4)(-) and [CH(3)(CH(2))(3)](4)N(+) in a microliter-range volume of chlorobenzene using acetone as disperser solvent. When solid samples were analyzed, the method consisted of a combination of ultrasound-assisted extraction and dispersive liquid-liquid microextraction with final detection by electrothermal-atomic absorption spectrometry. Since an HCl medium was required for the formation of the AuCl(4)(-) complex, HCl together with HNO(3) was used as extractants for ultrasound-assisted extraction. After optimization, the enrichment factor obtained was 220 for water samples. Moreover, the extraction efficiency was around 96%. The repeatability, expressed as relative standard deviation ranged from 3.6% to 9.7%. The instrumental detection limit was 8.4 ng L(-1), whereas the procedural detection limits were 42 ng L(-1) for water samples and 1.5 ng g(-1) for environmental solid samples.
authors.affiliation: Departamento de Química Analítica y Alimentaria, Área de Química Analítica, Facultad de Química, Universidad de Vigo, Campus As Lagoas-Marcosende s/n, 36310 Vigo, Spain.
authors.forename: I
authors.initials: I
authors.lastname: De La Calle
authors.forename: F
authors.initials: F
authors.lastname: Pena-Pereira
authors.forename: N
authors.initials: N
authors.lastname: Cabaleiro
authors.forename: I
authors.initials: I
authors.lastname: Lavilla
authors.forename: C
authors.initials: C
authors.lastname: Bendicho