Comparative study of metal ion interactions with wool keratin using chemometrics

Abstract

Uptakes of chromium(m), copper(Ir), iron(Ii), nickel(I1) and zinc(n) by wool were determined by inductively coupled plasma atomic emission and flame atomic absorption spectrometry. The order of uptakes at 100 "C for these metal ions was found to be Cu" > > Zn" > Crm > Fen > Ni".Further, the metal ion-treated wool samples were submitted to Fourier transform infrared spectrometric analysis, which was facilitated by chemometric methods (principal components analysis, soft independent modelling of class analogies and fuzzy clustering). This revealed the order of structure modification at the carboxyl group as a result of metal ion-wool interactions to be Crm > Cun > > Zn" > Fe" = Ni". The difference between the above two rank orders suggests that relatively large uptakes do not necessarily lead to the most significant structurally interactive effects in wool keratin.

The influence of copper(II) ions on wool photostability in the dry state

“…As a protein fibre, wool has polar and ionisable groups on the side chain of constituent amino acid residues that can bind both inorganic and organic charged molecules . A wide range of metal ions can be bound to wool, such as aluminium, mercury, copper, iron, nickel, zinc, cobalt, chromium, silver and gold .…”

“…Previous studies have shown that the formation of metal–wool complexes primarily takes place at free carboxyl groups in the wool, and relatively large uptakes of metal ions do not necessarily lead to significant structural changes in wool keratin . Smith and co‐workers suggested that metal ions could bind to a number of functional groups in proteins, such as carboxylic acid groups and sulphur‐containing groups.…”

Process intensification of catalysed henry reaction using copper-wool catalyst in a spinning mesh disc reactor

“…Along with the reduced intensity of the peak at 2929 cm -1 , it can be inferred that PEI was successfully immobilised on wool [9]. In the FTIR spectra of copper wool, there is a reduction in the intensity of peaks at 1523 cm -1 , 1639 cm -1 and 1234 cm -1 indicating the interaction of the metal with the amide I (N-H stretching bond), amide II (C-N stretching bond) and amide III (N-H bending bond) indicating the formation of copper-keratin complex on wool [26]. The immobilisation of copper on wool was further confirmed by UV spectroscopy.…”

Marginal marine agglutinated foraminifera: affinities for mineral phases

“…Proteinaceous substances in the test walls of the agglutinated foraminifera would cause absorptions to occur in these spectral regions. l n all spectra, carbonyl ( G O , stretch) and N-H (bending) vibrations are identified at around 1650cm-' relating to the amide 1 unit, the main peptide link, of a protein (Kokot et a/., 1994). Within the amide 1 region, small absorptions can identify features of the secondary structure of the protein i.e.…”

“…Absorptions in the regions 1500-1600 and 2800-3000cm-' arise from the vibration of organic materials in the test wall. The broad absorption between 3000 and 3800 cm-l is produced from fundamental OH-stretching vibrations in inorganic and organic materials (Graetsch et al, 1985), and N-H bond stretches from organic materials (Kokot et al, 1994).…”