مقاله انگلیسی رایگان در مورد ریز استخراج فاز جامد بنزن، تولوئن ، اتیل بنزن و زایلن ها از محلول های آبی – الزویر 2017

Abstract

Water-insoluble β-cyclodextrin polymer was synthesized by chemical cross-linking using epichlorohydrin (EPI) as a cross-linker agent. The produced water-insoluble polymer was used as a sorbent for the micro-solid phase extraction (μ-SPE) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water samples. The μ-SPE device consisted of a sealed tea bag envelope containing 15 mg of sorbent. For the evaluation of the extraction efficiency, parameters such as extraction and desorption time, desorption solvent and salt concentration were investigated. At an extraction time of 30 min in the course of the extraction process, analytes were extracted from a 10 mL aqueous sample solution. The analytes were desorbed by ultrasonication in 200 μL of acetonitrile for 20 min. Analysis of the analytes was done by a gas chromatography-flame ionization detector (GC–FID) system. The enrichment factor (EF) was found to be in the range 23.0–45.4 (EFmax = 50.0). The method provided linearity ranges of between 0.5 and 500.0 ng/mL (depending on the analytes), with good coefficients of determination (r2) ranging between 0.997 and 0.999 under optimized conditions. Detection limits for BTEX were in the range of between 0.15 and 0.60 ng/mL, while corresponding recoveries were in the range of 46.0–90.0%. The relative standard deviation of the method for the analytes at 100.0 ng/mL concentration level ranged from 5.5 to 11.2% (n = 5). The proposed method was concluded to be a cost effective and environmentally-friendly extraction technique with ease of operation and minimal usage of organic solvent.

Introduction

Despite substantial technological advances in the field of analytical chemistry, most instruments are still not capable of directly handling relatively complex samples. Therefore, sample preparation step is critical to obtain reliable and accurate final results. New trends in sample preparation are exemplified by miniaturization of the extraction apparatus, reduction of pretreatment steps and time, and improvement of selectivity to reduce matrix effects. In the past 20 years, many efforts have been devoted to develop these ideas. The latter approach includes solid-phase microextraction (SPME) and liquid-phase microextraction (LPME) [1,2]. SPME is a fast, simple, and green sample preparation technique that combines preconcentration and cleanup steps into a single step; however, it has some disadvantages as well. The main drawbacks of SPME include (i) high analysis cost per sample because of using dedicated and expensive apparatus, (ii) degradation of fibers through increased usage, and (iii) carryover between extractions [3]. Basheer et al. reported a novel extraction and preconcentration technique, termed micro-solid-phase extraction (-SPE), based on the packing of sorbent material in a sealed porous polypropylene membrane envelope to overcome, atleast partially,these disadvantages [4]. It was demonstrated to be a fast, accurate, and effective pretreatment technique. This method was subsequently applied for the determination of various target compounds in a variety of matrices [4–6].