http://hdl.handle.net/10204/896 2013-06-19T03:12:31Z http://hdl.handle.net/10204/6785 Title: A study of polymerization of aspen (Populus) wood lipophilic extractives by SEC and Py-GC/MS Authors: Sithole, B; Lapierre, L; Watanabe, C Abstract: Studies have been conducted on the formation of polymerised wood resin in model compounds and in lipophilic extracts of aspen. Our studies indicate that polymerization of wood resin components occurs during seasoning of aspen wood. The polymerization probably occurs via oxidation of fatty acids, especially the unsaturated ones, and glyceride components. It results in formation of products that are difficult to dissolve in normal solvents, depending on the extent of the polymerization. Also, the polymerization seems to result in the formation of sterols, compounds that are typically associated with “aspen wax”. This implies that the seasoning practices used in aspen mills can result in the formation of polymerized wood resin that will be difficult to remove if present in pulp and paper products. On the other hand, these problems may be minor compared to using unseasoned wood. Description: Copyright: 2013. Appita. This is the definitive version of the work. 2013-03-01T00:00:00Z http://hdl.handle.net/10204/6770 Title: Electrocatalytic properties of prussian blue nanoparticles supported on poly(m-aminobenzenesulphonic acid)-functionalised single-walled carbon nanotubes towards the detection of dopamine Authors: Adekunle, AS; Farah, AM; Pillay, J; Ozoemena, KI; Mamba, BB; Agboola, BO Abstract: Edged plane pyrolytic graphite electrode (EPPGE) was modified with and without Prussian blue (PB) nanoparticles and polyaminobenzene sulphonated single-walled carbon nanotubes (SWCNTPABS) using the chemical deposition method. The electrodes were characterised using microscopy, spectroscopy and electrochemical techniques. Results showed that edged plane pyrolytic graphite-single-walled carbon nanotubes-prussian blue (EPPGE-SWCNT-PB) electrode gave the best dopamine (DA) current response, which increases with increasing PB layers. The catalytic rate constant of 1.69 × 105 mol-1 cm3 s-1, Tafel value of 112 mV dec-1, and limit of detection of DA (2.8 nM) were obtained. Dopamine could be simultaneously detected with ascorbic acid. The electrode was found to be electrochemically stable, reusable and can be used for the analysis of DA in real drug samples. Description: Copyright: 2012 Elsevier. This is the Pre/post print version of the work. The definitive version is published in Colloids and Surfaces B: Biointerfaces, vol. 95, pp 186-194 2012-06-01T00:00:00Z http://hdl.handle.net/10204/6758 Title: Using Py-GC/MS to fingerprint additives associated with paper mill effluent toxicity episodes Authors: Sithole, BB; Pimentel, J; Gibbons, S; Watanabe, C Abstract: Understanding the cause of effluent toxicity is an important requirement for its prevention, remediation and return to compliance. One component of the strategy entails identification and fingerprinting of additives or components in additives that may be the cause of the toxicity episodes. A number of additives used in pulp and papermaking are polymeric compounds that are suspect in effluent toxicity. Their analysis and detection is difficult as they are not amenable to analysis by normal techniques applicable to mill effluents such as gas chromatography. Py-GC/MS is a powerful analytical technique that can be used to fingerprint these additives. The presence of the additives is confirmed by fingerprint pyrograms of the additives (or components in the formulations of the additives) in conjunction with mass spectrometry. The technique has been used to fingerprint and quantify polymeric additives associated with mill effluent toxicity episode Description: Copyright: 2012 The Royal Society of Chemistry 2012-10-01T00:00:00Z http://hdl.handle.net/10204/6675 Title: The short and long of it: shorter chromatographic analysis suffice for sample classification during UHPLC-MS-based metabolic fingerprinting Authors: Madala, NE; Tugizimana, F; Steenkamp, PA; Piater, LA; Dubery, IA Abstract: Ultra high-performance liquid chromatography hyphenated to mass spectrometry (UHPLC-MS) technologies has been widely applied in metabolomics, and the high resolution and peak capacity thereof are only some of the key aspects that are exploited in such and related fields. In the current study, we investigated if low resolution chromatography, with the aid of multivariate data analyses, could be sufficient for a metabolic fingerprinting study that aims at discriminating between samples of different biological status or origin. UHPLC-MS data from chemically-treated Arabidopsis thaliana plants were used and chromatograms with different gradient lengths were compared. MarkerLynxTM technology was employed for data mining, followed by principal component analysis (PCA) and orthogonal projections to latent structure discriminant analysis (OPLS-DA) as multivariate statistical interpretations. The results showed that, despite the congestion in low resolution chromatograms (of 5 and 10 min), samples could be classified based on their respective biological background in a similar manner as when using chromatograms with better resolution (of 20 and 40 min). This paper thus underlines that, in a metabolic fingerprinting study, low resolution chromatography together with multivariate data analyses suffice for biological classification of samples. The results also suggest that, depending on the initial objective of the undertaken study, optimisation in chromatographic resolution prior to full scale metabolomics studies is mandatory. Description: Copyright: 2012 Springer-Verlag. This is an ABSTRACT ONLY. The definitive version is published in Chromatographia, vol.76,(5-6), pp 279-285 2013-03-01T00:00:00Z