Co-precipitation-assisted coacervative extraction coupled to high-performance liquid chromatography: an approach for determining organophosphorus compounds in water samples

MAMMANA, SABRINA B.; BERTON, PAULA; CAMARGO, ALEJANDRA B.; LASCALEA, GUSTAVO E.; ALTAMIRANO, JORGELINA C.

Simposio; BFR 2017 ? VIII International Symposium on Flame Retardants; 2017

Organophosphorus (OPs) compounds are a large and diverse class of chemicals that have been synthesized for several purposes such as chemical weapons, flame retardants, ectoparasiticides and agrochemicals [1]. They are inhibitors of the acetylcholinesterase enzyme resulting in muscarinic and nicotinic symptoms and signs, even at low levels [1]. Drinking water is one of the main exposure routes to OPs for humans. There are current reports about water samples with OPs concentration up to 100 ng mL-1 [2]. Do to their toxicity and potential risk for human health; it is required sensitive and selective analytical methodologies for analyzing OPs in water samples. The instrumental techniques generally reported for determination of OPs include high performance liquid chromatography (HPLC) with diode array detection as well as mass spectrometry and, to a lesser extent, gas chromatography with nitrogen-phosphorus electron capture and flame photometric detectors [3]. It is well known that the sample preparation step plays an important role in the analytical methodology for achieving the required analytical performance for determining OPs at trace levels. As alternative to traditional pre-treatment techniques, e. g., liquid-liquid extraction or solid-phase extraction, green analytical techniques have been used for extraction and preconcentration of OPs. Coacervative extraction (CAE) technique is based on the use of ionic surfactants for extraction of analytes from aqueous samples [4]. Combination of CAE with co-precipitation agents that leads to a new analytical approach, named co-precipitation-assisted coacervative extraction (cop-CAE) technique [5], which has been recently investigated and applied in analytical chemistry. This technique is based on the formation of aggregated structures called ?hemimicelles?, by mean of electrostatic interactions between monomers of ionic surfactant and complex species oppositely charged [5]. The aim of this work was to propose a cop-CAE technique for extraction and preconcentration of OPs in water samples after their HPLC analysis. The methodology was applied for determining five of the most used OPs in agriculture and indoor in Argentina as target analytes: guthion, fenitrothion, parathion, methidathion and chlorpyrifos for their determination in tap and well water samples by HPLC-UV. The methodology was validated in terms of limits of detection (LODs), reproducibility, recovery (%) and linear working range and its fulfill US-EPA guidelines [6]. The developed methodology was applied for analyzing water samples from different locations of Mendoza.