title: Determination of low cadmium concentrations in wine by on-line preconcentration in a knotted reactor coupled to an inductively coupled plasma optical emission spectrometer with ultrasonic nebulization.
abstract: An on-line cadmium preconcentration and determination system implemented with inductively coupled plasma optical emission spectrometry (ICP-OES) associated to flow injection (FI) with ultrasonic nebulization system (USN) was studied. The cadmium was retained as the cadmium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, Cd-(5-Br-PADAP), complex, at pH 9.5. The cadmium complex was removed from the knotted reactor (KR) with 3.0 mol/L nitric acid. A total enhancement factor of 216 was obtained with respect to ICP-OES using pneumatic nebulization (12 for USN and 18 for KR) with a preconcentration time of 60 s. The value of the detection limit for the preconcentration of 5 mL of sample solution was 5 ng/L. The precision for 10 replicate determinations at the 5 microg/L Cd level was 2.9% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for cadmium was linear with a correlation coefficient of 0.9998 at levels near the detection limits up to at least 1,000 microg/L. The method was successfully applied to the determination of cadmium in wine samples.
authors.affiliation: Instituto de Investigaciones Mineras, Facultad de Ingeniería, Universidad Nacional de San Juan, Argentina.
authors.forename: R F
authors.initials: RF
authors.lastname: Lara
authors.forename: R G
authors.initials: RG
authors.lastname: Wuilloud
authors.forename: J A
authors.initials: JA
authors.lastname: Salonia
authors.forename: R A
authors.initials: RA
authors.lastname: Olsina
authors.forename: L D
authors.initials: LD
authors.lastname: Martinez
mesh_terms: D002104:Cadmium / Q000032:analysis*; D002138:Calibration; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D005506:Food Contamination / Q000032:analysis; D009862:Online Systems; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000295:instrumentation / Q000379:methods / Q000592:standards; D014465:Ultrasonics; D014920:Wine / Q000032:analysis*
chemical_list: D002104:Cadmium