title: Utility of solid phase extraction for spectrophotometric determination of gold in water, jewel and ore samples.
abstract: A highly sensitive, selective and rapid method for the determination μg L(-1) level of Au(III) based on the rapid reaction of Au(III) with 2,3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline (DCHNAQ) and the solid phase extraction of the colored complex with a reversed phase polymer-based C18 cartridge have been developed. The DCHNAQ reacted with Au(III) to form a violet complex of a molar ratio 3:1 [DCHNAQ to Au(III)] in the presence of 5.0 M of phosphoric acid solution and Triton X-100 medium. This complex was enriched by the solid phase extraction with a polymer-based C18 cartridge. The enrichment factor of 100 was achieved. The molar absorptivity of the complex is 2.73×10(5) l mol(-1) cm(-1) at 633 nm in the measured solution. The system obeys Beer's law in the range of 0.02-1.30 μg ml(-1), whereas the optimum concentration ranges obtained from Ringbom plot was 0.08-1.24 μg ml(-1). The relative standard deviation for ten replicates sample of 0.6 μg ml(-1) level is 1.28%. The detection and quantification limits, are 6.1 and 19.5 ng ml(-1) in the original sample. This method was applied to the determination of gold in water, jewel and ore samples with good results comparing to the GFAAS method.
authors.affiliation: Chemistry Department, Faculty of Science, Benha University, Benha, Egypt. asamin2005@hotmail.com
authors.forename: Alaa S
authors.initials: AS
authors.lastname: Amin
mesh_terms: D000042:Absorption; D000143:Acids / Q000737:chemistry / Q000494:pharmacology; D002138:Calibration; D006046:Gold / Q000737:chemistry* / Q000493:pharmacokinetics; D017612:Gold Compounds / Q000737:chemistry; D055498:Jewelry / Q000032:analysis*; D009281:Naphthalenes / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods* / Q000706:statistics & numerical data; D013053:Spectrophotometry / Q000379:methods; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000494:pharmacology; D014867:Water / Q000737:chemistry* / Q000378:metabolism
chemical_list: C532533:2,3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline; D000143:Acids; D017612:Gold Compounds; D009281:Naphthalenes; D011810:Quinoxalines; D013501:Surface-Active Agents; D014867:Water; D006046:Gold