title: Ultratrace determination of arsenic in water samples by electrothermal atomic absorption spectrometry after pre-concentration with Mg-Al-Fe ternary layered double hydroxide nano-sorbent.
abstract: A selective solid phase extraction method, based on nano-structured Mg-Al-Fe(NO3(-)) ternary layered double hydroxide as a sorbent, is developed for the pre-concentration of ultra-trace levels of arsenic (As) prior to determination by electrothermal atomic absorption spectrometry. It is found that both As(III) and As(V) could be quantitatively retained on the sorbent within a wide pH range of 4-12. Accordingly, the presented method is applied to determination of total inorganic As in aqueous solutions. Maximum analytical signal of As is achieved when the pyrolysis and atomization temperatures are close to 900 °C and 2300 °C, respectively. Several variables affecting the extraction efficiency including pH, sample flow rate, amount of nano-sorbent, elution conditions and sample volume are optimized. Under the optimized conditions, the limit of detection (3Sb/m) and the relative standard deviation are 4.6 pg mL(-1) and 3.9%, respectively. The calibration graph is linear in the range of 15.0-650 pg mL(-1) with a correlation coefficient of 0.9979, sorption capacity and pre-concentration factor are 8.68 mg g(-1) and 300, respectively. The developed method is validated by the analysis of a standard reference material (SRM 1643e) and is successfully applied to the determination of ultra-trace amounts of As in different water samples.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Azarbaijan Shahid Madani University, 35 Km Tabriz-Marageh Road, P.O. Box 53714-161, Tabriz, Iran. Electronic address: h.abdol@azaruniv.edu.
authors.forename: Hossein
authors.initials: H
authors.lastname: Abdolmohammad-Zadeh
authors.forename: Abolghasem
authors.initials: A
authors.lastname: Jouyban
authors.forename: Roghayeh
authors.initials: R
authors.lastname: Amini
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry; D001151:Arsenic / Q000032:analysis*; D002138:Calibration; D060766:Drinking Water / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D005618:Fresh Water / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D008276:Magnesium Hydroxide / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D012015:Reference Standards; D052616:Solid Phase Extraction / Q000379:methods; D013054:Spectrophotometry, Atomic / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D060766:Drinking Water; D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; C021024:ferric hydroxide; D000536:Aluminum Hydroxide; D001151:Arsenic; D008276:Magnesium Hydroxide
keywords: Arsenic; Electrothermal atomic absorption spectrometry; Layered double hydroxide; Nano-sorbent; Solid phase extraction; Water samples