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The interactions of the sugars glucose and lactose with the transport protein bovine serum albumin (BSA) were investigated using fluorescence, FT-IR and circular dichroism (CD) techniques. The results indicated that glucose could be bonded and transported by BSA, mainly involving hydrogen bonds and van der Waals interactions (ΔH = -86.13 kJ mol(-1)). The obtained fluorescence data from the binding of sugar and BSA were processed by the multivariate curve resolution-alternating least squares (MCR-ALS) method, and the extracted concentration profiles showed that the equilibrium constant, rglucose:BSA, was about 7. However, the binding of lactose to BSA did not quench the fluorescence significantly, and this indicated that lactose could not be directly transported by BSA. The binding experiments were further performed using the fluorescence titration method in the presence of calcium and BSA. Calcium was added so that the calcium/BSA reactions could be studied in the presence or absence of glucose, lactose or hydrolysis products. The results showed that hydrolyzed lactose seemed to enhance calcium absorption in bovine animals. It would also appear that for children, lactose provides better nutrition; however, glucose is better for adults.

Molybdenum disulfide (MoS2) is an emerging material with some unique physical and electronic properties somewhat comparable to those of graphene. It was prepared with the use of a simple hydrothermal process, and has a layered structure similar to that of graphene. Also, it has a peroxidase-like catalytic activity and is able to catalyze the oxidation of the colorless peroxidase substrate, 3,3',5,5'-tetramethylbenzidine (TMB), in the presence of H2O2 to produce a blue product. This reaction used MoS2 as a useful peroxidase, which involved a colorimetric method for trace analysis of H2O2 in water, e.g. lake waters. This method is uncomplicated, inexpensive and highly sensitive for H2O2 in the 0.125-1.75 μM range (LOD: 0.08 μM). It is also quite stable in the presence of many common inorganic and organic potentially interfering compounds, e.g. metal ions as well as amino acids and sugars.

Various rice samples were collected in Vietnam from the Red River region, and some other parts of the country as well as from Yanco, NSW, Australia. The rice samples were analysed for 14 elements (P, K, Mg, Ca, Mn, Zn, Fe, Cu, Al, Na, Ni, As, Mo, and Cd) by ICP-AES, ICP-MS and FAAS. The analytical procedures were carefully controlled and validated using the rice flour certified material (NIES No 10). In general, the results showed that Vietnamese rice has elemental concentration ranges similar to those of the Australian and other overseas rice. However, analyses for some elements are characteristic of some Vietnamese and Australian rice samples. Thus, Vietnamese rice shows somewhat higher levels of P, K and Mg than rice samples from other countries; Mn could be a marker for the Australian rice grown in the Yanco region, and the analysed Australian samples were also very low in Cd (0.003 mg kg-1). An unusual distribution of Ni, present in higher concentrations in the white rice samples than in the brown ones, was observed for some Vietnamese rice samples.

Raw naturally coloured and white cotton cellulose fibres were investigated by Fourier transform near-infrared (FT-NIR) spectroscopy and chemometric methods, namely principal component analysis (PCA). In general, the white cotton exhibited bands that could be associated with the structural features of the cotton cellulose polymer. But the FT-NIR spectrum of the green cotton, which is reported for the first time, exhibited a sharp band at 4250 cm–1. Further band analysis indicated that green cotton contains a higher C–H content and a lower C–C/C–O and O–H fractions than other natural cotton fibres, suggesting that it has undergone an oxidation process as indicated in the previous FT-Raman spectroscopic study (see Liu, Y., Kokot, S., and Sambi, J., Analyst, 1998, 123, 633). Although the PCA scores plot of FT-NIR spectra of seven types of cotton fibres showed no better separation than that of FT-Raman spectra, it is still possible to differentiate the various types of natural cotton fibres.

An electrochemical method involving a gold nanoparticle modified glassy carbon electrode (AuNPs/GCE) was researched and developed for the simultaneous analysis of three β(2)-agonists, ractopamine (RAC), salbutamol (SAL) and clenbuterol (CLB). The three analytes were electrocatalytically oxidized at the AuNP/GCE, which enhanced the oxidation peak current and influenced the shift of the oxidation potentials to lower values in comparison with the analysis involving only the GCE. The differential pulse stripping voltammetry (DPSV) voltammograms from the drug mixture produced complex, overlapping profiles, and chemometrics methods were applied for calibration modeling. The peak currents associated with RAC, SAL and CLB measurements were linear as a function of their concentrations (ranges within 0.005-0.150 μg mL(-1)); the detection limits for RAC, SAL and CLB were 2.4, 5.8 and 2.6 ng mL(-1), respectively. It was shown that satisfactory quantitative results were obtained with the use of the MVC1 package of chemometrics methods e.g. the PLS1 calibration model produced a relative prediction error (RPE(T)) of 7.0% and an average recovery of 97.6%. The above AuNP/GCE was successfully employed for the simultaneous analysis of RAC, SAL and CLB in pork meat, liver and pig feed samples.

The versatility of FTIR spectrometry was explored by considering a variety of samples drawn from industrial applications, materials science and biomedical research. These samples included polymeric insulators, bauxite ore, clay, human hair and human skin. A range of sampling techniques suitable for these samples is discussed, in particular FTIR microscopy, FTIR emission spectroscopy, attenuated total reflectance and photoacoustic FTIR spectrometry. The power of modern data processing techniques, particularly multivariate analysis, to extract useful information from spectral data is also illustrated.

The interaction of aspirin and ibuprofen with bovine serum albumin (BSA) was studied by spectrofluorimetry under simulated physiological conditions. Both aspirin and ibuprofen quenched the intrinsic fluorescence of BSA and the binding ratios obtained were 2 : 1 for aspirin-BSA and 3 : 1 for ibuprofen-BSA interactions, respectively. The thermodynamic parameters (ΔH, ΔS and ΔG) obtained from the fluorescence spectroscopy data showed that the binding of aspirin to BSA involved van der Waals interactions and hydrogen bonds. Competitive experiments using warfarin and diazepam as site markers indicated that aspirin was mainly located in the hydrophobic pocket of site II of the protein as well as to a small extent in site I. Furthermore, the competitive interaction of the aspirin and ibuprofen with BSA, which was studied with the use of the three-way excitation-emission fluorescence spectra and a parallel factor analysis (PARAFAC) chemometrics method, showed that the competitive effect of ibuprofen was stronger than that of aspirin, i.e. the former molecule replaced the aspirin from the aspirin-BSA complex.

Beta-agonists such as ractopamine (RAC) and clenbuterol (CLEN), have similar effects as anabolic steroids i.e. they promote growth of muscular tissue and reduce body fat. They have been used successfully with animals and humans but have also been banned in many countries principally, because of their serious side effects. However, their illegal use persists. Thus, their interaction with biomolecules such as bovine serum albumin (BSA) is of significance, especially the co-operative reaction of mixed ligands with the protein. Fluorescence and UV-vis spectra of complex mixtures of individual ligands, binary and ternary complexes with BSA resulted in significantly overlapping spectral profiles. Qualitative and quantitative information about the various complex ligand-protein species formed, was obtained with the resolution of the excitation-emission fluorescence three-way data matrices by chemometrics methods-MCR-ALS and PARAFAC. Individual spectra of the ligands, their binary complexes with BSA and their ternary complexes were extracted, and quantitative concentration profiles for each species in a particular interaction were constructed. Such analyses made it possible to interpret the role and behaviour of each reaction component. It was found that both ligands, RAC and CLEN, bound co-operatively in site I of the BSA. This was confirmed with the use of site markers such as warfarin (site I) and ibuprofen (site II). However, CLEN formed a 1:1 CLEN-BSA complex, while RAC formed a 2:1 RAC(2)-BSA binary species. Interestingly, when CLEN or RAC was added to RAC(2)-BSA or CLEN-BSA, respectively, ternary complexes were produced such as RAC(2)-BSA-CLEN. Significantly, the presence of the second ligand in such an interaction in excess, appeared to increase the affinity of the added ligand for BSA. This may have consequences on the amount of steroid required to achieve a desired tissue growth effect.

Three commonly used fluoroquinolone antibiotics (norfloxacin (NFX), ofloxacin (OFX) and lomefloxacin (LMFX)) were used as examples of molecules which can interact with a biomacromolecule, such as DNA, separately or in a mixture. Such interactions were investigated with the use of UV and Synchronous Fluorescence Spectroscopy (SFS). Equilibrium binding (K(ap)) and Stern-Volmer equilibrium (K(SV)) constants were extracted from these two types of spectra from interactions of DNA with single fluoroquinolones. The values of these equilibrium constants were relatively low, and this suggested that the DNA groove was the likely binding site. The complex SFS profiles obtained from the interactions of the DNA with the drug analyte mixtures were resolved, with the use of the curve resolution method, parallel factor (PARAFAC) analysis, into spectra of individual drugs. From these spectra, the (K(SV)) values for the individual analytes in the mixture were obtained. Also extracted were the concentrations of the individual quinolones as a function of concentration of the DNA. From a comparison of the equilibrium constants for the individual drug-DNA interaction with those obtained from the interaction with the drugs in a mixture, it was found that the binding strength of a single analyte to DNA was LMFXNFXOFX, but when the drug mixture was involved, this order was reversed. Importantly, it was also found that the equilibrium uptake of the drugs OFX and NFX was higher than from single drug-DNA experiments; the concentrations of LMFX did not change significantly. These observations collectively suggested that the binding of NFX and OFX to DNA is synergistically affected and that they probably share similar binding sites, while the LMFX was bound to a different site. This new important qualitative and quantitative information, which can now act as a springboard for more complex and deeper studies of the apparent synergistic effects of drug interactions with biomacromolecules, could only be obtained by the combination of three-way array SFS measurements and their interpretation by a chemometrics curve resolution method such as PARAFAC.

Rice samples were obtained from the Red River region and some other parts of Vietnam as well as from Yanco, Australia. These samples were analysed for 14 elements (P, K, Mg, Ca, Mn, Zn, Fe, Cu, Al, Na, Ni, As, Mo and Cd) by ICP-AES, ICP-MS and FAAS as described in Part 1. This data matrix was then submitted to multivariate data analysis by principal component analysis to investigate the influences of environmental and crop cultivation variables on the elemental content of rice. Results revealed that geographical location, grain variety, seasons and soil conditions are the most likely significant factors causing changes in the elemental content between the rice samples. To assess rice quality according to its elemental content and physio-biological properties, a multicriteria decision making method (PROMETHEE) was applied. With the Vietnamese rice, the sticky rice appeared to contain somewhat higher levels of nutritionally significant elements such as P, K and Mg than the non-sticky rice. Also, rice samples grown during the wet season have better levels of nutritionally significant mineral elements than those of the dry season, but in general, the wet season seemed to provide better overall elemental and physio-biological rice quality.

Uptakes of chromium(III), copper(II), iron(II), nickel(II) and zinc(II) 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 CuII≫ ZnII > CrIII > FeII > NiII. 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 CrIII > CuII≫ ZnII > FeII≈ NiII. 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.

A simple and rapid method for the simultaneous polarographic determination of pyrazine and its methyl derivatives (up to four components) has been developed. The potential was scanned from –600 to – 1000 mV by differential-pulse polarography. A solution containing a phosphate—citric acid buffer and a potassium chloride supporting electrolyte (pH 4.8; l= 0.5 mol l–1) was used. Under these conditions, high measurement sensitivities for the pyrazines were achieved. The pulse amplitude, scan rate and the time interval were –50 mV, –10 mV s–1 and 600 ms, respectively. However, because of severe overlap of the polarograms for pyrazines under these conditions, the Kalman filter method was used for the determination and curve resolution of individual components. In contrast to conventional implementation of the Kalman filter, a measurement function derived from a known set of mixed pyrazines was found to yield the best results in this work.