title: Spectrofluorometric determination and chemical speciation of trace concentrations of chromium (III & VI) species in water using the ion pairing reagent tetraphenyl-phosphonium bromide.
abstract: A highly selective, and low cost extractive spectrofluorometric method has been developed for determination of trace concentrations of chromium (III & VI) in water samples using the fluorescent reagent tetraphenylphosphonium bromide (TPP(+) · Br(-)). The method was based upon solvent extraction of the produced ion associate [TPP(+) · CrO(3)Cl(-)] of TPP(+) · Br(-) and halochromate in aqueous HCl and measuring the fluorescence quenching of TPP(+) · Br(-) in chloroform at λ(ex/em)=242/305 nm. The fluorescence intensity of TPP(+)Br(-) decreased linearly on increasing the chromium (VI) concentration in the range of 1-114 μg L(-1). The limits of detection (LOD) and quantification (LOQ) of chromium (VI) were 0.43 and 1.42 μg L(-1), respectively. Chromium (III) species after oxidation to chromium (VI) with H(2)O(2) in alkaline solution were also determined. Chemical speciation of chromium (III & VI) species at trace levels was achieved. The method was applied for analysis of chromium in certified reference material (IAEA Soil-7) and in tap- and wastewater samples and compared successfully (>95%) with the inductively coupled plasma-mass spectrometry (ICP-MS) results.
authors.affiliation: Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia. mohammad el shahawi@yahoo.co.uk
authors.forename: M S
authors.initials: MS
authors.lastname: El-Shahawi
authors.forename: H M
authors.initials: HM
authors.lastname: Al-Saidi
authors.forename: A S
authors.initials: AS
authors.lastname: Bashammakh
authors.forename: A A
authors.initials: AA
authors.lastname: Al-Sibaai
authors.forename: M A
authors.initials: MA
authors.lastname: Abdelfadeel