title: Direct introduction of water sample in multisegmented flow-injection analysis for sulfide determination.
abstract: The present paper describes an inline flow-injection analysis system for the determination of sulfide in water samples, exploiting the Fischer reaction. Water samples were collected and introduced into a reactor of the FIA system. The sulfide released, after sample acidification, was carried out with a nitrogen gas flow and mixed with N,N diethyl-p-phenylenediamine (DEPD) solution in the presence of Fe(III). The blue dye formed was measured in the wavelength range between 672-679 nm. An evaluation of the effects of chemical and flow factors was performed using the factorial design of two levels, while optimization was accomplished by a Doehlert matrix. The system presented two linear-response ranges: the first of 0.433 to 400 µg L(-1) and the second of 400 to 3500 µg L(-1). The detection and quantification limit were found to be 0.130 and 0.433 µg L(-1), respectively, while the sample throughput was 12 h(-1). The precision was evaluated as the relative standard deviation (n = 10); for 50 and 100 µg L(-1) sulfide it was found to be 1.9 and 2.3%, respectively. The method showed satisfactory selectivity regarding the main interference present in environmental samples. The accuracy of the method was successfully evaluated in environmental water samples after a comparison with a literature reference method.
authors.affiliation: Universidade Federal de Alfenas, Instituto de Ciências Exatas, Alfenas, MG, Brazil.
authors.forename: Giovana F
authors.initials: GF
authors.lastname: Lima
authors.forename: Ariadne M
authors.initials: AM
authors.lastname: Brondi
authors.forename: Ana L S F
authors.initials: AL
authors.lastname: Paiva
authors.forename: César R T
authors.initials: CR
authors.lastname: Tarley
authors.forename: André F
authors.initials: AF
authors.lastname: de Oliveira
authors.forename: Célio
authors.initials: C
authors.lastname: Wisniewski
authors.forename: Pedro O
authors.initials: PO
authors.lastname: Luccas
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry; D017022:Flow Injection Analysis / Q000379:methods*; D057230:Limit of Detection; D009584:Nitrogen / Q000737:chemistry; D010655:Phenylenediamines / Q000737:chemistry; D013440:Sulfides / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005290:Ferric Compounds; D010655:Phenylenediamines; D013440:Sulfides; D014874:Water Pollutants, Chemical; C013935:N,N-diethyl 4-phenylenediamine; D009584:Nitrogen