title: A new flow injection preconcentration method based on multiwalled carbon nanotubes for the ETA-AAS determination of Cd in urine.
abstract: A new flow injection (FIA) procedure for the preconcentration of cadmium in urine using multiwalled carbon nanotubes (MWCNT) as sorbent and posterior electrothermal atomization atomic absorption spectrometry (ETA-AAS) Cd determination has been developed. Cadmium was retained in a column filled with previously oxidized MWCNTs and it was quantitatively eluted with a nitric acid solution. The parameters influencing the adsorption-elution process such as pH of the sample solution, amount of sorbent and flow rates of sample as well as eluent solutions have been studied. Cd concentration in the eluent was measured by ETA-AAS under the optimized conditions obtained. The results indicated the elimination of urine matrix effect as a consequence of the preconcentration process performed. Total recovery of cadmium from urine at pH 7.2 using a column with 45 mg of MWCNTs as sorbent and employing a HNO(3) 0.5 mol L(-1) solution for elution was attained. The detection limit obtained was 0.010 μg L(-1) and the preconcentration factor achieved was 3.4. The method showed adequate precision (RSD: 3.4-9.8%) and accuracy (mean recovery: 97.4-100%). The developed method was applied for the determination of cadmium in real urine samples from healthy people (in the range of 0.14-2.94 μg L(-1)) with satisfactory results.
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo, Spain.
authors.forename: Jennifer Álvarez
authors.initials: JÁ
authors.lastname: Méndez
authors.forename: Julia Barciela
authors.initials: JB
authors.lastname: García
authors.forename: Rosa M Peña
authors.initials: RM
authors.lastname: Crecente
authors.forename: Sagrario García
authors.initials: SG
authors.lastname: Martín
authors.forename: Carlos Herrero
authors.initials: CH
authors.lastname: Latorre
mesh_terms: D002104:Cadmium / Q000652:urine*; D017022:Flow Injection Analysis; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon; D013054:Spectrophotometry, Atomic / Q000379:methods*
chemical_list: D037742:Nanotubes, Carbon; D002104:Cadmium