Spectrophotometric studies of the interaction of noble metals with quercetin and quercetin-5'-sulfonic acid.
Results of some studies on the interaction of noble metals with quercetin (Q) and quercetin-5'-sulfonic acid (QSA), the compounds of flavonoid group, are presented. The reactions of chloride complexes of the metals: RuOHCl5(2-), PdCl4(2-), OsCl6(2-), PtCl6(2-) and AuCl4- with both reagents were examined. The redox reactions of ruthenium and gold with Q and QSA have been identified. The reaction of the metals with both reagents results in the formation of the oxidized form of Q that exhibits maximum absorbance at 291 nm. Ruthenium and gold react with the examined reagents under similar conditions: 0.04 M HCl and 1 x 10(-4) M Q (or QSA). The CH3OH + H2O (1:1) (Q) and pure aqueous (QSA) media can be used. The reaction of gold with Q is slow at room temperature. It can be accelerated by heating the solution being examined. The reaction proceeds significantly faster when the water-soluble sulfonic derivative of quercetin, quercetin-5'-sulfonic acid, is used as a reagent. The new species formed can make the basis of spectrophotometric methods for the determination of ruthenium and gold. The molar absorptivities at 291 nm are equal to 5.0 x 10(3) and 2.2 x 10(4) L mol(-1) cm(-1) for Ru and Au, respectively, independently of the reagent used. Some methods for the determination of the content of gold (0.04%) in a cosmetic cream were developed.
Balcerzak
Maria
M
Department of Analytical Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland. mbal@ch.pw.edu.pl
Kopacz
Maria
M
Kosiorek
Anna
A
Swiecicka
Elzbieta
E
Kus
Stanisław
S
D003358:Cosmetics / Q000032:analysis; D017612:Gold Compounds / Q000032:analysis* / Q000737:chemistry; D017892:Osmium Compounds / Q000032:analysis / Q000737:chemistry; D010084:Oxidation-Reduction; D010165:Palladium / Q000032:analysis / Q000737:chemistry; D017671:Platinum Compounds / Q000032:analysis / Q000737:chemistry; D011794:Quercetin / Q000031:analogs & derivatives* / Q000737:chemistry*; D012015:Reference Standards; D017975:Ruthenium Compounds / Q000032:analysis* / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
D003358:Cosmetics; D017612:Gold Compounds; D017892:Osmium Compounds; D017671:Platinum Compounds; D017975:Ruthenium Compounds; C502510:quercetin-5'-sulfonic acid; C038016:gold chloride; C030173:platinum chloride; D010165:Palladium; D011794:Quercetin; C008756:palladium chloride; C038365:ruthenium chloride