Daryl J. Tucker

Studies on Wool Yellowing Part III: Sunlight Yellowing

The yellowing of wool fabrics caused by exposure to sunlight differs from that produced by some artificial light sources. Atlhough the initial pH of the fabric has little effect on the rate of sunlight yellowing in the pH range 4-10, mild treatment with alkali subsequent to yellowing increases the discoloration. The effects that bleaching, shrinkproofing, and other chemical treatments have on yellowing by subsequent exposure to sunlight are discussed.

Determination of morphine in water immiscible process streams using sequential injection analysis coupled with acidic permanganate chemiluminescence detection

A procedure for the determination of morphine in non-aqueous, water immiscible, process streams by sequential injection analysis is presented. Detection was based upon the chemiluminescence reaction of morphine with acidic potassium permanganate in the presence of sodium polyphosphate, which was carried out in a heterogeneous reaction environment. The calibration graph (range 0.005–0.12% m/v) was non-linear, with a polynomial equation of best fit of y = –384x2 + 139x – 4.84 (R2 = 0.9990), where y represents the singal (mV) and x represents the morphine concentration (% m/v), and was analytically useful over the range 0.01–0.1% m/v. Precision (as measured by relative standard deviation) was 6.0% for 10 replicate analyses of a non-aqueous morphine standard (0.075% m/v).Methyltriphenylphosphonium permanganate was investigated as an alternative chemiluminescent reagent and was found to deliver a similar analytical performance to potassium permanganate. Sequential injection analysis coupled with chemiluminescence detection afforded results for the determination of morphine in non-aqueous process samples which were in good agreement with those obtained using a standard liquid chromatographic method, with an analytical throughput in excess of 120 h–1.

Quantitation of tryptophan and other plasma amino acids by automated pre-column o-phthaldialdehyde derivatization high-performance liquid chromatography: improved sample preparation

Pre-column derivatization with o-phthaldialdehyde is a rapid and sensitive method for the quantitation of amino acids in biological fluids. This method uses acetonitrile as a deproteinizing reagent which gives improved recovery of tryptophan compared with 5-sulfosalicylic acid and permits the measurement of aspartic acid which coelutes with 5-sulfosalicylic acid. The method is automated to increase reproducibility and convenience. Mean coefficients of variation for peak areas relative to internal standard were 3.2 and 5.2% for amino acid standards and plasma samples, respectively. The presence of nitrilotriacetic acid stabilized the o-phthaldialdehyde reagent which is important in an automated system. The method is suitable for the analysis of large numbers of plasma samples where total tryptophan and aspartic acid are of interest.

Studies in Wool Yellowing: Part VII: Processes for Retarding Yellowing by Sunlight

The use of thiourea-formaldehyde resin for retarding the rate of yellow ing of wool by sunlight has been examined. This method provides considerable protection against yellowing, particularly of wet fabrics. It has been found that treatment with thiourea- formaldehyde mixtures. which does not give rise to resin, provides similar protection against yellowing. This modification has the advantages that the handle and color of the wool are unaffected, As for the resin treatment, initial rinsing reduces the pro tective effect, although this is not further reduced by subsequent washing.

A study of the electrochemistry of tryptophan, peptides containing tryptophan, and related compounds (indoles) at mercury electrodes

Abstract The electrochemistry of nineteen indole compounds of the general formula has been studied at mercury electrodes by differential pulse polarography, dc polarography, cyclic voltanunetry, cathodic stripping voltammetry, electrocapillary curves and controlled potential electrolysis in aqueous buffered media. Provided R1 = H, and the double bond is present between R2 and R3, a reversible oxidation process is observed at mercury electrodes which involves the formation of a mercury(II)-indole complex. Analysis of the wave shape, pH dependence, and concentration dependence of the oxidation process leads to the conclusion that the overall reaction is described by the equation 2InH + Hg ⇌ HgIn2 + 2H+ + 2 e− (process 1) where InH = indole with R1 = H. For some compounds a surface controlled second oxidation process is observed at more positive potentials than process one when high concentrations of indole are used. The presence of reactant and product adsorption is revealed by electrocapillary curves, cyclic voltammetric experiments and by the concentration dependence. Strong product adsorption can be used as the basis of a highly sensitive, but non-specific method for the determination of indole by differential pulse cathodic stripping voltammetry.

Analysis of the Intercellular and Membrane Lipids of Wool and Other Animal Fibers

We report our analysis of the sterol and fatty acid composition of wools from different breeds of sheep and from different climatic zones. The results are compared with analyses of other protein fibers. Cholesterol, desmosterol, palmitic, stearic and oleic acids account for the majority of the internal lipids in animal fibers, with the exception of human hair and fibers of the camel family. We conclude that sterol and fatty acid analyses can be a useful additional procedure to the conventional methods for distin guishing between animal fibers.

Electrochemical reduction of pyrethroid insecticides in non-aqueous solvents

Abstract The pyrethrins (as pyrethrum extract), pyrethrin I, pyrethrin II, allethrin and tetramethrin may be reduced in acetonitrile and methanol at mercury and glassy carbon electrodes. In contrastm no well-defined electrochemical processes were observed for phenothrin, bioresmethrin or permethrin. With the exception of the initial, reversible reduction response of tetramethrin in acetonitrile, the reduction processes are irreversible on the voltammetric timescale. Under conditions of controlled potential electrolysis (CPE) and in acetonitrile, the initial reduction of tetramethrin to the anion radical is followed by ester cleavage to yield the chrysanthemate anion as the major product. Evidence is also observed in acetonitrile for ester cleavage following reductive bulk electrolysis of allethrin and pyrethrum extract. In methanol and acetonitrile solutions containing phenol, tetramethrin is reduced in an irreversible two-electron process on both voltammetric and CPE timescales and cyclohexane-1,2-dicarboximide chrysanthemate is obtained as the major product. No products were identified following CPE of allethrin or pyrethrum extract in methanol. A method for the determination of allehtrin in an insecticide formulation containingpermethrin was developed using the reduction response at a glassy carbon electrode and the technique of differential pulse voltemmetry, after simple dilution of the formulation in acetonitrile. An allethrin concentration of 2.8 ± 0.2 gl −1 was obtained compared with the manufacturers stated value of 3.0 gl −1 .

Cyclopropene fatty acids of six seed oils from malvaceae

Seeds ofHibiscus leptocladus, H. sturtii, Sida echinocarpa, Abutilon amplum, Gossypium robinsonii andLagunaria patersonii contained 11.2\s-26.8% oil and 11.6\s-18.2% protein. Spectral, chromatographic and chemical analyses of the seed oils revealed the presence of malvalic (0.5\s-3.2%), sterculic (0.1\s-1.7%) and dihydrosterculic (trace-0.7%) acids.

Lanasol dyes and wool fibres. Part I: model studies on the mechanism of dye fixation in a mixed solvent system

The mechanism of fixation of Lanasol dyes, which are distinguished by their α-bromoacrylamido reactive group, to the various amino acid side chain sites within wool protein is quite complex. It has been proposed that the reaction could proceed by either a nucleophilic substitution or Michael addition pathway. We have investigated this mechanism through the reaction between model dye compounds which possess either an α-bromoacrylamido or α, β-dibromopropionamido group and wool mimetics that contain amine, thiol and hydroxyl groups. These latter groups are typical of the reactive sites found in wool proteins. The reactions were carried out in an acetone-water solvent system. The reactions were monitored by HPLC and the products were isolated and then characterised by proton and carbon-13 NMR, and mass spectroscopy. The results of the study confirmed that the dibromo form of the dye reactive group is only converted to the monobromo form in the presence of model wool compounds and that both forms react with these model wool compounds to yield the same products. When the nucleophilic moiety was an amine, the reaction terminated with a product containing an aziridine ring. No evidence for the proposed reaction of this aziridine ring with a second nucleophilic moiety to form a cross-link could be detected. The thiol of cystiene and imidazole of histidine were also found to reaction with the model dyes.

New Cell for the Fourier Transform Raman Analysis of Fiber and Textile Samples

A new cell has been developed for the measurement of fiber and textile samples using FT-Raman spectroscopy. It improves the strength of the signal over that of conventional solid cells by the compression of the samples to be analyzed and the use of a mirror to reflect scattered radiation back out of the cell and into the collection lens of the spectrometer. The new cell also eliminates the problem of cell window material interfering with the sample spectrum, since the laser passes through a windowless aperture to reach the sample. This consideration is particularly important when spectra are being obtained from weakly scattering samples. The design, optimization, and use of the new cell are presented. The performance of the new cell in terms of improvements in signal-to-noise ratio and elimination of spectral artifacts is compared to that of other conventional sampling techniques. Significant improvements in spectral quality were obtained from both natural and synthetic fiber and textile samples.