title: Using activated attapulgite as sorbent for solid-phase extraction of melamine in milk formula samples.
abstract: In this study, a simple solid-phase extraction (SPE) approach by using activated attapulgite as sorbent was successfully developed for the determination of melamine in milk formula samples. Crucial factors impacting the extraction efficiency, including sample solvent, elution solvent, and sample loading volume, were investigated. Under the optimal extraction conditions, the sample loading volume was up to 200 mL and the adsorption capacity of the melamine gave rise to 1154 μg g(-1). Excellent linear calibration curves (r (2)  > 0.999) were achieved, and then the limit of detection (S/N = 3) and the limit of quantification (S/N = 10) were found to be 0.15 and 0.5 ng mL(-1), respectively. The recoveries of the melamine spiked in four milk formula samples at three concentration levels ranged from 83.5 to 111.0 % with relative standard deviations (RSDs) less than 10.2 %. Furthermore, RSDs of batch to batch (n = 4) of the acidified attapulgite used in this developed method were in the range of 2.3∼7.3 %. In comparison to the commercial Oasis MCX, the acidified attapulgite sorbent even outperformed (at least in terms of reproducibility) for melamine analysis in real food samples. Because of its simplicity, the newly developed SPE method based on acidified attapulgite nanoparticles should provide a promising tool for daily monitoring of doped melamine in milk formula or other complex matrices.
authors.affiliation: School of Materials and Chemical Engineering/School of Safety Engineering, Ningbo University of Technology, Ningbo, Zhèjiāng, 315016, China. shiming-49@163.com.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Wang
authors.affiliation: Obstetrical Department, Affiliated Hospital of Ningbo University School of Medicine, Ningbo, Zhèjiāng, 315016, China.
authors.forename: Rong-Rong
authors.initials: RR
authors.lastname: Xuan
authors.affiliation: Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 25 N. Wolfe Street, Baltimore, MD, 21205-2185, USA.
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Ma
authors.affiliation: Ningbo Entry-Exit Inspection and Quarantine Bureau, Ningbo, Zhèjiāng, 315016, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Tan
authors.affiliation: School of Materials and Chemical Engineering/School of Safety Engineering, Ningbo University of Technology, Ningbo, Zhèjiāng, 315016, China.
authors.forename: Zhen-Feng
authors.initials: ZF
authors.lastname: Jin
authors.affiliation: Ningbo Entry-Exit Inspection and Quarantine Bureau, Ningbo, Zhèjiāng, 315016, China.
authors.forename: Yi-Hui
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning, 116023, China.
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning, 116023, China.
authors.forename: Yu-Kui
authors.initials: YK
authors.lastname: Zhang
mesh_terms: D000327:Adsorption; D000818:Animals; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D057230:Limit of Detection; D017616:Magnesium Compounds / Q000737:chemistry*; D008892:Milk / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*; D014227:Triazines / Q000032:analysis / Q000302:isolation & purification*
chemical_list: D017616:Magnesium Compounds; D017655:Silicon Compounds; D014227:Triazines; C011907:melamine; C026325:attapulgite
keywords: Attapulgite; Hydrophilic interaction; Ion exchange interaction; Milk formula sample; Solid-phase extraction