ORCID Profile
0000-0003-1530-4405
Current Organisations
RMIT University
,
Latrobe University
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Publisher: Elsevier BV
Date: 05-2013
Publisher: Elsevier BV
Date: 08-2021
Publisher: No publisher found
Date: 2019
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.FOODCHEM.2015.02.044
Abstract: Resistant starch has potential health benefits but the factors affecting its formation in bread and baked products are not well studied. Here, the formation of resistant starch in wholemeal bread products was evaluated in relation to the processing conditions including fermentation time, temperature and the inclusion of palm oil as a vitamin source. The effects of each the factor were assessed using a full factorial design. The impact on final starch content of traditional sourdough fermentation of wholemeal rye bread, as well as the bulk fermentation process of wheat and wheat/oat blends of wholemeal bread, was also assessed by enzyme assay. Palm oil content was found to have a significant effect on the formation of resistant starch in all of the breads while fermentation time and temperature had no significant impact. Sourdough fermentation of rye bread was found to have a greater impact on resistant starch formation than bulk fermentation of wheat and wheat blend breads, most likely due the increased organic acid content of the sourdough process.
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.JCHROMB.2015.02.045
Abstract: Polybrominated diphenyl ethers (PBDEs) have become ubiquitous environmental contaminants due to their incorporation into many consumer products. Their ability to bioaccumulate to alarming levels in fat-rich matrices such as fish demands fast and efficient methods to monitor these contaminants. We present an analytical method for selective-pressurised liquid extraction (S-PLE) of PBDEs from fish tissue. Fat removal performance of different mixtures of Florisil, silica gel and sulphuric acid-impregnated silica gel were evaluated using a response surface experimental design approach for determining the optimal fat-retaining mixture for S-PLE. Acid-silica gel had the greatest in idual effect on fat retention with a two-thirds acid-silica one-third Florisil mixture found to be the most efficient (>97%). Method validation was performed using recovery experiments at three spiked concentration levels (0.05, 0.5 and 5ngg(-1) ww). Mean recoveries of target analytes in spiked s les ranged from 70 to 124%, with relative standard deviations <27%. The S-PLE lipid removal efficiency combined with the sensitivity of triple quadrupole mass spectrometers provides a fast and comparatively inexpensive analytical method for analysis of PBDEs in fish s les.
Publisher: Elsevier BV
Date: 10-2010
Publisher: Elsevier BV
Date: 07-2000
DOI: 10.1016/S0165-022X(00)00054-3
Abstract: A stepwise approach was used to develop a supercritical fluid extraction (SFE) method for analysis of synthetic pyrethroids (SPs) on a wool matrix, commencing with a simple inert matrix to examine the solubility of the pyrethroids in the extraction fluid CO(2) and then extended to the real wool matrix. Chemometric approaches were used to determine the SFE optimum conditions. It was found that pyrethroids were readily extractable from an inert matrix over a wide range of pressure (170-350 atm) and at low temperature (<90 degrees C). Subambient hexane efficiently trapped the compounds from the depressurised fluid. Excessively high pressure and temperature resulted in poor trapping, isomerisation and possibly degradation of some components. With spiked wool s les method modifications focused on reducing the coextraction of grease, a bulk matrix component of raw wool. By using alumina (containing 8% moisture) and operating the extraction at 50 degrees C, 200 atm for 60 min, sufficiently clean extracts of pyrethroids suitable for gas chromatography-electron-capture detection analysis were obtained. The recoveries of all SPs were satisfactory (78-101%) over the range of 0.5-5 microg/g levels of these compounds. The precision of the entire analysis procedure was comparable to the conventional Soxhlet extraction method. Detection limits of some commonly used SPs for sheep treatment were also evaluated. Comparable results relative to those achieved by solvent extraction for incurred wool s les were obtained with a recovery of 81-85%. The results, however, suffered high uncertainties (R.S.D. approximately 19-24%) due to the small amount of wool s le taken in each extraction and the suspected inhomogeneity of the wool. Different persistences of cypermethrin isomers in wool were observed.
Publisher: Elsevier BV
Date: 04-2010
Publisher: Wiley
Date: 10-2006
Abstract: Mixtures comprising nitrofuran antibiotics (NFA) and nitrofuran metabolites (NFM) were resolved for the first time by using MEKC. Sodium deoxycholate (SDC) was chosen as the micelle-forming surfactant. Optimization of separation conditions was achieved by using a central composite experimental design (CCD) approach. Experimental parameters such as concentration ratio of borate to phosphate in the buffer, pH of the running electrolyte and voltage were investigated. The effect of concentration of the surfactant on resolution was significant. Under optimal conditions of 80 mM SDC, pH 9.0, (20 mM borate + 20 mM phosphate) and 16 kV, the resolution between eight consecutive peak pairs ranged from 1.9 to 11.8. Due to the absence of a UV-active chromophore in the metabolites, they were derivatized with 2-nitrobenzaldehyde (2-NBA). In order to mimic a proposed extraction procedure for the analysis of both NFA and/or derivatized NFM in a s le, aqueous s les (prederivatized with 2-NBA) were extracted by using C(18) SPE cartridges. After washing with H(2)O, the cartridges were eluted with a small portion of organic solvent with weak elution characteristics to remove excess 2-NBA (hexane was chosen). Target analytes were then recovered with ACN. Excellent reproducibility of migration time (t(mig)) was achieved for all analytes using the developed MECC approach, with absolute t(mig) <1% RSD and t(mig) ratio <0.2% RSD, and peak area ratio was 4% RSD. The LOD for each compound, calculated by extrapolating to an S/N of 3, were found to be 0.19-2.0 microg/mL.
Publisher: IGI Global
Date: 2018
DOI: 10.4018/978-1-5225-3142-5.CH030
Abstract: Modern instruments have the capacity to generate and store enormous volumes of data and the challenges involved in processing, analyzing and visualizing this data are well recognized. The field of Chemometrics (a subspecialty of Analytical Chemistry) grew out of efforts to develop a toolbox of statistical and computer applications for data processing and analysis. This chapter will discuss key concepts of Big Data Analytics within the context of Analytical Chemistry. The chapter will devote particular emphasis on preprocessing techniques, statistical and Machine Learning methodology for data mining and analysis, tools for big data visualization and state-of-the-art applications for data storage. Various statistical techniques used for the analysis of Big Data in Chemometrics are introduced. This chapter also gives an overview of computational tools for Big Data Analytics for Analytical Chemistry. The chapter concludes with the discussion of latest platforms and programming tools for Big Data storage like Hadoop, Apache Hive, Spark, Google Bigtable, and more.
Publisher: Elsevier BV
Date: 12-2015
Publisher: Springer Science and Business Media LLC
Date: 2004
Publisher: Elsevier BV
Date: 12-1996
Publisher: Elsevier BV
Date: 04-1997
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 08-2003
DOI: 10.1016/S0021-9673(03)01021-5
Abstract: One of the major techniques used for the method development of ternary and quaternary high performance liquid chromatography (HPLC) systems has been to use mixture designs, often referred to as "Glajch's Triangle". This technique does not allow for the systematic and simultaneous optimization of other factors such as gradient time, pH and temperature that affect the quality of separations. An alternative approach is to use experimental designs. The condition, however, that the composition of all components of the mobile phase must total 100% presents a problem when trying to mathematically represent ranges of each mobile phase constituent of a ternary or quaternary system. A method is described here, based on spherical coordinate representations, that adheres to the constraints of the mobile phase composition and allows experimental designs, such as central composite and factorial designs, to be applied to the simultaneous optimization of the mobile phase composition. Other factors, in particular temperature and gradient time, can then be included in the design. As a result of applying these designs to the HPLC separation of phenols and corticosteroids, it was found necessary to include three-way interactions between experimental factors in the model. The significance of these interactions shows that they need to be considered in HPLC method development.
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.FOODCHEM.2017.01.140
Abstract: Resistant starch (RS) can form during storage of foods, thereby bestowing a variety of potential health benefits. The purpose of the current study has been to determine the influence of storage temperature and time on the crystallinity and RS content of bread. Loaves of white bread were baked and stored at refrigeration, frozen and room temperatures with analysis over a period of zero to seven days. RS determination and X-ray diffraction (XRD) were used to evaluate the influence of storage temperature and time on total crystallinity and RS content. The rate of starch recrystallisation was affected by storage temperature and time, where refrigeration temperatures accelerated RS formation and total crystallinity more than storage time at both frozen and room temperature. A strong statistical model has been established between RS formation in bread and XRD patterns, having a 96.7% fit indicating the potential of XRD to measure RS concentrations.
Publisher: Wiley
Date: 08-2016
Publisher: Elsevier BV
Date: 2009
Publisher: Elsevier BV
Date: 03-2002
DOI: 10.1016/S0731-7085(01)00659-8
Abstract: Box-Behnken experimental designs do not appear to be extensively used in optimisation of analytical methods using capillary electrophoresis (CE). This paper describes the use of the Box-Behnken experimental design to optimise the factors affecting the separation of ethambutol hydrochloride (EB), its impurity 2-amino-1-butanol and the internal standard (phenylephrine hydrochloride) in a CE method for a pharmaceutical tablet assay. The three factors studied simultaneously were: buffer pH, buffer concentration and applied electric field, each at three levels. The method was optimised with respect to three responses: resolution between peaks, theoretical plate count and the migration time of the EB peak. A statistical programme, which applies a multiple response optimisation algorithm, was used to calculate and optimise the three responses simultaneously. The optimum conditions were established to be 58.0 mM sodium borate buffer at pH 9.50 and an applied electric field of 412 V/cm. The robustness of the method was also determined and confirmed using a second Box-Behnken design, as part of the validation exercise. System suitability values for the method were derived from the regression surface analysis. The CE method for a pharmaceutical tablet formulation was further validated according to current regulatory requirements, with respect to linearity and range, precision, specificity, accuracy and limit of quantitation. The optimised method gives a fast and efficient separation under 4 min, with complete resolution between the three peaks, and represents an improvement over the existing USP method. It can be concluded that the Box-Behnken experimental design provides a suitable means of optimising and testing the robustness of a CE pharmaceutical method.
No related grants have been discovered for Jeff Hughes.