Determination of Chlorobenzenes and Nitrobenzoates in Wastewater by Dispersive Liquid-Liquid Microextraction Coupled to Capillary Gas Chromatography

Abstract

Abstract.A fast, eco-friendly and reliable method combining dispersive liquid-liquid microextracion (DLLME) with capillary gas chromatography (GC) was developed for the simultaneous determination of p-dichlorobenzene (p-DCB), o-dichlorobenzene (o-DCB), nitrobenze (NB), 1,2,4-trichlorobenzene (TCB), and 3-nitrotoluene (NT) in wastewater. To achieve this goal, dispersive liquid-liquid microextraction (DLLME) was applied as a sample preparation technique. The DLLME parameters such as the types and volume of extraction solvent, the types and volume of the disperser solvent, pH value and salt addition were investigated and optimized. The method was linear in the ranges from 2.2 × 10 -2 to 200 µg·mL -1 for aforementioned compounds with R 2 ≥ 0.9987. The DLLME procedure allowed efficient recovery of these compounds ranging between 89 % and 104 % with a relative standard deviation (RSD) ≤ 9.6 (n=6) for genuine wastewater samples spiked with 10, 50 and 100 µg·mL -1 of standard substances, respectively. These results showed the potential of this technique for chlorobenzenes and nitrobenzoates monitoring in wastewater samples. Furthermore, the methods are simple, reproducible, and inexpensive. IntroductionChlorobenzenes and nitrobenzoates are extensively used during experiments and productions, and also are typically dangerous, explosive, flammable, toxic, and environmentally hazardous [1]. Therefore, the detection of these compounds is hence important which ensures the safety of human health and properties and also avoids environmental disasters. Numerous methodologies have been demonstrated to determination of chlorobenzenes and nitrobenzoates, such as gas chromatography-mass spectrometry (GC-MS) [2][3][4], high performance liquid chromatography-mass spectrometry (HPLC-MS) [5], sensors [1,6,7] etc.Dispersive liquid-liquid microextraction (DLLME) has emerged recently as a new and very efficient alternative technique to concentrate target analytes dissolved in organic extracts, allowing a high enrichment factor in a simple and quick manner [8]. DLLME has been applied for determination of a vast variety of organic and inorganic compounds in different matrices [9,10]. In this paper, DLLME-GC was established for the determination of chlorobenzenes and nitrobenzoates in wastewater, and the features of this method were discussed in detail in the following sections.