title: Application of factorial design and Doehlert matrix for determination of trace lead in environmental samples by on-line column preconcentration FAAS using silica gel chemically modified with niobium(V) oxide.
abstract: In this study a new method for Pb determination in water using solid phase extraction coupled to a flow injection system and flame atomic absorption spectrometry was developed. The sorbent used for Pb preconcentration and extraction was silica gel chemically modified with niobium(V) oxide. Flow and chemical variables of the system were optimized through a multivariate procedure. The factors selected were buffer type, eluent concentration, and sample and eluent flow rates. It was verified that the aforementioned factors as well as their interactions were statistically significant at the 95% confidence level. The effect of foreign ions was evaluated using a fractionary factorial experimental design. The detection limit was 0.35 microg L(-1) and the precision was 1.6%. Results for recovery tests using different environmental samples were between 90 and 104%. Certified reference materials were analyzed in order to check the accuracy of the proposed method.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Brazil.
authors.forename: Kalya Cravo Di Pietro
authors.initials: KC
authors.lastname: Roux
authors.forename: Heloisa França
authors.initials: HF
authors.lastname: Maltez
authors.forename: Jeferson Schneider
authors.initials: JS
authors.lastname: Carletto
authors.forename: Edmar
authors.initials: E
authors.lastname: Martendal
authors.forename: Eduardo
authors.initials: E
authors.lastname: Carasek
mesh_terms: D000465:Algorithms; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D005782:Gels / Q000737:chemistry; D007854:Lead / Q000032:analysis* / Q000737:chemistry; D009556:Niobium / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000295:instrumentation / Q000379:methods; D013054:Spectrophotometry, Atomic / Q000295:instrumentation / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D005782:Gels; D010087:Oxides; D014874:Water Pollutants, Chemical; D009556:Niobium; D007854:Lead; D012822:Silicon Dioxide