The formation of micellar aggregates in the presence of calcium(II) ions in solutions containing sodium and taurodeoxycholate ions and their composition at 25 degrees C and in 0.5 mol dm(-3) N(CH(3))(4)Cl as constant ionic medium was studied. The study was carried out by means of two different procedures. In the first one, solid calcium oxalate was equilibrated with taurodeoxycholate, sodium and hydrogen ions and the free concentration of sodium and hydrogen ions was determined. After filtration, the calcium(II) (by atomic absorption spectrophotometry) and oxalate concentration were also determined. In the second approach, hydrogen and sodium ions free concentrations were obtained by electromotive force measurements carried out in solutions containing taurodeoxycholate. The results of both procedures could be explained by assuming the presence of aggregates of different composition with the participation of sodium, calcium(II) and taurodeoxycholate ions, depending on the concentration of the reagents. Protonated species were even present in appreciable concentrations. All the found species have taurodeoxycholate aggregation numbers in multiples of three. A mechanism for the micellar aggregates containing calcium and sodium is proposed. Sodium taurodeoxycholate in the presence of calcium(II) forms larger aggregates than does taurocholate in the presence of calcium(II); the building block of the former is a trimer whereas the latter system has lower aggregation numbers and its building block is a dimer or an octamer.
An investigation on calcium taurodeoxycholate micellar aggregates / Antonilli, Marco; Bottari, Emilio Giovanni; Festa, Maria Rosa; Gentile, Lorella. - In: CHEMICAL SPECIATION AND BIOAVAILABILITY. - ISSN 0954-2299. - STAMPA. - 22:2(2010), pp. 115-126. [10.3184/095422910x12694549467335]
An investigation on calcium taurodeoxycholate micellar aggregates
ANTONILLI, MARCO;BOTTARI, Emilio Giovanni;FESTA, Maria Rosa;GENTILE, LORELLA
2010
Abstract
The formation of micellar aggregates in the presence of calcium(II) ions in solutions containing sodium and taurodeoxycholate ions and their composition at 25 degrees C and in 0.5 mol dm(-3) N(CH(3))(4)Cl as constant ionic medium was studied. The study was carried out by means of two different procedures. In the first one, solid calcium oxalate was equilibrated with taurodeoxycholate, sodium and hydrogen ions and the free concentration of sodium and hydrogen ions was determined. After filtration, the calcium(II) (by atomic absorption spectrophotometry) and oxalate concentration were also determined. In the second approach, hydrogen and sodium ions free concentrations were obtained by electromotive force measurements carried out in solutions containing taurodeoxycholate. The results of both procedures could be explained by assuming the presence of aggregates of different composition with the participation of sodium, calcium(II) and taurodeoxycholate ions, depending on the concentration of the reagents. Protonated species were even present in appreciable concentrations. All the found species have taurodeoxycholate aggregation numbers in multiples of three. A mechanism for the micellar aggregates containing calcium and sodium is proposed. Sodium taurodeoxycholate in the presence of calcium(II) forms larger aggregates than does taurocholate in the presence of calcium(II); the building block of the former is a trimer whereas the latter system has lower aggregation numbers and its building block is a dimer or an octamer.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.