title: On-line separation and preconcentration of inorganic arsenic and selenium species in natural water samples with CTAB-modified alkyl silica microcolumn and determination by inductively coupled plasma-optical emission spectrometry.
abstract: A new, simple, and selective method has been presented for the separation and preconcentration of inorganic arsenic (As(III)/As(V)) and selenium (Se(IV)/Se(VI)) species by a microcolumn on-line coupled with inductively coupled plasma-optical emission spectrometry (ICP-OES). Trace amounts of As(V) and Se(VI) species were separated and preconcentrated from total As and Se at desired pH values by a conical microcolumn packed with cetyltrimethylammonium bromide (CTAB)-modified alkyl silica sorbent in the absence of chelating reagent. The species adsorbed by CTAB-modified alkyl silica sorbent were quantitatively desorbed with 0.10 ml of 1.0 mol l(-1) HNO(3). Total inorganic arsenic and selenium were similarly extracted after oxidation of As(III) and Se(IV) to As(V) and Se(VI) with KMnO(4) (50.0 micromol l(-1)). The assay of As(III) and Se(IV) were based on subtracting As(V) and Se(VI) from total As and total Se, respectively. All parameters affecting the separation/preconcentration of As(V) and Se(VI) including pH, sample flow rate and volume, eluent solution and volume have been studied. With a sample volume of 3.0 ml, the sample throughput was 24h(-1) and the enrichment factors for As(V) and Se(VI) were 26.7 and 27.6, respectively. The limits of detection (LODs) were 0.15 microg l(-1) for As(V) and 0.10 microg l(-1) for Se(VI). The relative standard deviations (RSDs) for nine replicate determinations at 5.0 microg l(-1) level of As(V) and Se(VI) were 4.0% and 3.6%, respectively. The calibration graphs of the method for As(V) and Se(VI) were linear in the range of 0.5-1000.0 microg l(-1) with a correlation coefficient of 0.9936 and 0.9992, respectively. The developed method was successfully applied to the speciation analysis of inorganic arsenic and selenium in natural water samples with satisfactory results.
authors.affiliation: Department of Chemistry, Wuhan University, Wuhan 430072, PR China.
authors.forename: Chaomei
authors.initials: C
authors.lastname: Xiong
authors.forename: Man
authors.initials: M
authors.lastname: He
authors.forename: Bin
authors.initials: B
authors.lastname: Hu
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000032:analysis*; D002138:Calibration; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000032:analysis / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007287:Inorganic Chemicals / Q000737:chemistry; D008956:Models, Chemical; D055095:Optics and Photonics; D011196:Potassium Permanganate / Q000737:chemistry; D015203:Reproducibility of Results; D012643:Selenium / Q000032:analysis*; D012822:Silicon Dioxide / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods*; D013501:Surface-Active Agents / Q000032:analysis / Q000737:chemistry*
chemical_list: D002593:Cetrimonium Compounds; D007287:Inorganic Chemicals; D013501:Surface-Active Agents; D011196:Potassium Permanganate; D012822:Silicon Dioxide; D012643:Selenium; D001151:Arsenic; D000077286:Cetrimonium