title: Graphene-modified TiO2 nanotube arrays as an adsorbent in micro-solid phase extraction for determination of carbamate pesticides in water samples.
abstract: Graphene is a good adsorbent for organic pollutants, especially for compounds containing benzene rings. When used in TiO2 nanotube arrays for micro-solid phase extraction (μ-SPE), the combination of graphene's strong adsorptive properties with its good separation capabilities results in excellent sample preconcentration performance. In the present study, graphene-modified TiO2 nanotube arrays were prepared by electrodeposition using a cyclic voltammetric reduction method. Four carbamate pesticides, including metolcarb, carbaryl, isoprocarb, and diethofencarb, were used as model analytes to validate the enrichment properties of the prepared adsorbent in μ-SPE. Factors affecting the enrichment efficiency of the μ-SPE procedure were optimized and included sample pH, elution solvents, salting-out effect, adsorption time and desorption time. Under optimal conditions, graphene-modified TiO2 nanotube arrays exhibited excellent enrichment efficiency for carbamate pesticides. The detection limits of these carbamate pesticides ranged from 2.27 to 3.26 μg L(-1). The proposed method was validated using four environmental water samples, and yields of pesticides recovered from spiked test samples of the four analytes were in the range of 83.9-108.8%. These results indicate that graphene-modified TiO2 nanotube arrays exhibit good adsorption to the target pollutants, and the method described in this work could be used as a faster and easier alternative procedure for routine analysis of carbamate pesticides in real water samples.
authors.affiliation: Beijing Key Laboratory of Oil and Gas Pollution Control, College of Geosciences, China University of Petroleum Beijing, Beijing 102249, China. Electronic address: zhouqx@cup.edu.cn.
authors.forename: Qingxiang
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Beijing Key Laboratory of Oil and Gas Pollution Control, College of Geosciences, China University of Petroleum Beijing, Beijing 102249, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Fang
mesh_terms: D000327:Adsorption; D002219:Carbamates / Q000032:analysis* / Q000737:chemistry* / Q000302:isolation & purification; D006108:Graphite / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D010575:Pesticides / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D052617:Solid Phase Microextraction / Q000379:methods*; D012997:Solvents / Q000737:chemistry; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D002219:Carbamates; D010575:Pesticides; D012997:Solvents; D014874:Water Pollutants, Chemical; D014867:Water; C009495:titanium dioxide; C065256:isoprocarb; D006108:Graphite; D014025:Titanium
keywords: Carbamate pesticides; Graphene; High performance liquid chromatography; Micro-solid phase extraction; TiO(2) nanotube arrays