Determination of triazines in hemodialysis saline solutions by adsorptive stripping voltammetry after extraction in acetonitrile

Abstract

A determinação de herbicidas 2-metiltio-4,6-dialquilamino-1,3,5-triazina (triazinas) em soluções salinas utilizadas em hemodiálise foi investigada por voltametria. Os herbicidas foram detectados com grande sensibilidade nas soluções salinas, após extração em fase de acetonitrila (ACN), utilizando o eletrodo de mercúrio de gota pendente. O efeito de salting out originado pelo meio salino existente nas soluções viabilizou as extrações. A relação de volumes entre as fases salina e de ACN foi investigada para alcançar a melhor sensibilidade na detecção das triazinas. A especiação entre as triazinas investigadas (ametrina, desmetrina, prometrina e terbutrina) não foi possível e recuperações entre 88 e 107% foram calculadas em amostras fortificadas com os analitos. Utilizando esta metodologia, limites de detecção de 0,03 µmol L -1 foram calculados para as triazinas nas amostras salinas.A method for the voltammetric determination of 2-methylthio-4,6-dialkylamino-1,3,5-triazine (triazines) herbicides in hemodialysis (HD) saline solutions was developed. The herbicides were detected in the saline solutions at the hanging mercury drop electrode (HMDE) with high sensitivities only after extraction of the analytes in acetonitrile (ACN). The salting out effect originated by the saline environment existing in the solutions enabled the extractions. The volume ratio between the saline and ACN phases was investigated in order to find the best sensitivity to detect the triazines. The speciation amongst them (ametryn, desmetryn, prometryn and terbutryn) was not possible. Recoveries between 88 and 107% were calculated in spiked samples, and detection limits of 0.03 µmol L -1 were calculated for the triazines in the saline samples using this methodology. Keywords: herbicides, triazines, hemodialysis, voltammetry IntroductionThe growing interest in the use of pesticides in agricultural production and their negative environmental impact has led to a number of studies for the development of different analytical methods. Besides the frequently used chromatographic measurements, voltammetry, mainly with differential pulse modes 1-9 should be taken into consideration as a fast, easy and inexpensive alternative. Additionally, the sensitivity of the electrochemical methods, their applicability over an unusually wide concentration range, is highly satisfactory for meeting requirements of toxicological, ecotoxicological and environmental regulation enforcement. 10 Hemodialysis (HD) solutions are prepared by mixing pure water and a high-salt (HS) content solution (about 7.0 mol L -1 ) to compose the final HD solution that has a salt concentration of about 0.2 mol L -1 . It is used to maintain the blood ionic equilibrium of the patients during the hemodialysis sessions. The presence of contaminants in the water or in HS solutions must be detected before a hemodialysis session as the HD solution remains very close to the blood of the patients separated only by the dialysis membranes. To aggravate the problem, the dialysis membranes can dialysate ...

Determination of ametryn in soils via microwave-assisted solvent extraction coupled to anodic stripping voltammetry with a gold ultramicroelectrode

“…The selectivity of the optimized procedure was tested in the presence of the most common herbicide from the striazine family, atrazine. In the literature, it is well established that traditional mercury electrodes are not adequate for selectively determining pesticides from this class [4][5][6][7][8][9][10][11][12]. When the mixture contains more than one triazine compound, only one polarogaphic cathodic peak is detected because the peak potential values are very close together [4][5][6][7][8][9][10][11][12].…”

“…Surveys of the distributions of triazine herbicides, such as ametryn (2-methylthio-4-ethylamino-6-isopropylamino-1,3,5-triazine) and atra-zine (2-chloro-4-ethylamino-6-isopropylamino-1,3, 5-triazine), in the environment are generally performed using gas chromatography, high performance liquid chromatography (HPLC) and thin-layer chromatogra-phy [3]. Among the electrochemical methods, polarog-raphy is the most commonly-used technique [4][5][6][7][8][9][10][11][12]. In addition to chromatographic methods, adsorptive stripping voltammetry (AdsV), the most sensitive electroanalytical technique currently available [13], has been proven to be suitable for trace analysis of pesticides [14].…”

“…Only mercury electrodes have been tested as working electrodes in AdsV, where they were used in the cathodic AdsV determination of s-triazine [4][5][6][10][11][12]. No study concerning anodic AdsV detection can be found in the literature.…”

Developing a continuous flow-square wave voltammetry method for determination of atrazine in soil solutions using the hanging mercury drop electrode

“…Massaropi et al 15 described the determination of picloram in natural waters using SWV and the hanging mercury drop electrode (HMDE). Determination of triazines in hemodialysis saline solutions by adsorptive stripping voltammetry onto the HMDE after extraction in acetonitrile was reported by Nascimento et al 19 Electroanalytical determination of atrazine with the HMDE has been reported in natural waters using differential pulse voltammetry 16 and square wave voltammetry in stationary 17 and flow conditions. 18 The atrazine molecule exhibits two two-electron reduction processes in acidic medium, in which the preceding protonation takes place (pK 1.44).…”

“…Electroanalytical techniques have been developed and applied for determination of herbicides in waters, soils and food. [14][15][16][17][18][19] De Souza et al 14 determined paraquat in natural water and commercial tea samples using gold electrodes obtained from recordable compact disc using square wave voltammetry (SWV). Massaropi et al 15 described the determination of picloram in natural waters using SWV and the hanging mercury drop electrode (HMDE).…”