title: Visual colorimetry for trace antimony(V) by ion-pair solid-phase extraction with bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) on a PTFE type membrane filter.
abstract: A new visual colorimetry for trace antimony(V) based on ion-pair solid-phase extraction to a PTFE-type membrane filter with bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) ion ([Co(5-Cl-PADAP)(2)](+)) has been developed. Experiments showed that hexachloroantimonate(V) ion (SbCl(6)(-)) was adsorbed with [Co(5-Cl-PADAP)(2)](+) to the front surface of the PTFE filter. The adsorption of antimony(V) ion was promoted by the addition of lithium chloride as a source of chloride ion. The excess reagent of [Co(5-Cl-PADAP)(2)](+) was eluted by rinsing with a 10 wt% methanol aqueous solution. In this case, the slow rate of the hydrolysis reaction of SbCl(6)(-) and the difference of the hydrophobicity of the ion pairs were important for adsorption and separation with a PTFE-type membrane filter. The antimony(V) concentration was determined through a visual comparison with a standard series. The visual detection limit was 0.10 microg. The calibration curve assessed with the reflection spectrometric responses at 580 nm was linear in the concentration range of 0.10 - 1.2 microg (r = 0.996). The proposed method has been applied to the determination of sub-microgram levels of antimony(V) ion in water samples.
authors.affiliation: Graduate School of Science and Engineering, Yamagata University, Yonezawa, Japan. mizu@yz.yamagata-u.ac.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mizuguchi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Takehito
authors.initials: T
authors.lastname: Mori
authors.forename: Atsushi
authors.initials: A
authors.lastname: Uehara
authors.forename: Yuta
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Endo
authors.forename: Junichi
authors.initials: J
authors.lastname: Shida
mesh_terms: D000327:Adsorption; D000965:Antimony / Q000032:analysis*; D003124:Colorimetry / Q000295:instrumentation / Q000379:methods; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D018021:Lithium Chloride / Q000737:chemistry; D008567:Membranes, Artificial; D000432:Methanol / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods*; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D008567:Membranes, Artificial; D009942:Organometallic Compounds; D012996:Solutions; C528549:bis(2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato)cobalt; D014867:Water; D011138:Polytetrafluoroethylene; D000965:Antimony; D018021:Lithium Chloride; D000432:Methanol