Long wavelength (>600nm) fluorescence has many advantages in analysis, including the presenting possibility of building compact, robust, yet sensitive instrumentation, where measurements can be made with minimal autofluorescence and scattered light from biological samples. With the requirement for high sensitivity in immunoassays, e.g., for environmental monitoring, clinical analysis and therapeutic drug monitoring, a novel, compact, fluorescence detection system (NFDS) was successfully constructed using several pulsed diode lasers as excitation sources, and a photodiode as optoelectronic sensor. It has the following characteristics: 1. Excitation source range: 600 nm- 900 run, and emission wavelength range: 650 run -1000 run. 2. Utilisation of various cut-off filters to eliminate undesirable background radiation and to define the fluorescence wavelength band. 3. Emission beam detection by means of an efficient, high speed and large area silicon photodiode. 4. An adjustable laser pulse frequency and linear optoelectronic amplification. 5. Digital display, output for a digital multimeter or a chart recorder, and analogue to digital converter (ADC) for connecting to a PC with a suitable data handling package. A 635 run-laser diode with the output power of 2 m Wand a 650 nm cut-off filter were used to test the detection limit of the naphthofluorescein fluorescence dye (NF) in 0.50 M Tris buffer (PH 8.8), containing 2.5% (w/v) 3-[(3-cholamidopropy)dimethylammonio ]-l-propanesulfonate (CHAPS). A 645 nm laser diode with the output power of 2m Wand a 665 nm cut-off filter were used to test the detection limit of Cy5 monofunctional dye (Cy5) in 0.50 M Tris buffer (pH8.8). A 670 nm laser diode with the output power of 2mW and a 690 nm cut-off filter were used to test the detection limit of Cy5.5 bisfuncational dye (Cy5.5) in 0.50 M Tris buffer (PH 8.8). A comparative test was carried out to assess the detection limit of Cy5 in 0.50 M Tris buffer (PH 8.8), using the NFDS with the RACALL-DANA 4009 digital multimeter and the Hitachi F-4500 commercial research grade fluorescence spectrometer. A flow injection immunoassay was developed using the a-Interferon as the analyte and Cy5 as the label. A calibration curve was obtained using the NFDS with the FlowTEK data capture software. The potential of this novel fluorescence detector has been demonstrated through hardware experimentation and practical investigation of detection limits and a flow injection immunoassay (FIlA). Its application could be extended by the use of superluminescent light emitting diodes (SLEDs) at shorter wavelengths (450 nm - 600 nm); a microprocessor based electronic system, and the LabVIEW 5.0 software for data capture.

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No description available.

Two novel microreactor cells for the investigation of catalysts by in-situ infrared spectroscopy under microwave and conventional heating are presented. A transmission infrared microreactor cell is demonstrated which holds a pressed catalyst disc in a controlled atmosphere and allows study of reactions from ambient temperatures to over 473 K. A cell that allows diffuse reflectance spectroscopy under reaction conditions up to 373 K under microwave heating and 423 K under conventional heating is also described. The optical characteristics of these cells are determined by the choice of CaF2 as the window material, allowing transmission from 77000-1110 cm−1. An oscillating microwave power heating regime was used to study the oxidation of carbon monoxide in air over the supported platinum catalysts EUROPT-1 and EUROPT-3, and their support oxides in these cells. The reaction was followed by time-resolved infrared spectroscopy and mass spectrometry. Both displayed a number of features that oscillated with the same frequency as the microwave perturbation. Production of CO2 appeared to vary with temperature in the same manner whether the catalysts were heated conventionally or with microwave radiation. Although no specific microwave effect for this reaction was observed, accurate thermometry within the cells was limited through the constraints imposed by microwave heating. Preliminary infrared emission and liquid phase experiments using the transmission cell are also reported.

This thesis is concerned with the electrochemical and spectroelectrochemical characterisation of cyano (CN) and trifluoromethyl (CF3) substituted polypyridine ligands and their metal complexes. The ligands investigated were X-CN-py (X = 3, 4 and 5, py = pyridine), X,X´-(CN)2-bpy) (X,X´ = 3,3´, 4,4´ and 5,5´ bpy = 2,2´- bipyridine) and X,X´-(CF3)2-bpy (X,X´ = 3,3´, 4,4´ and 5,5´). The Pt(II) complexes of the X-CN-py and X,X´-(CN)2-bpy ligands were studied along with the Fe(II) complexes of the X,X´-(CN)2-bpy and X,X´-(CF3)2-bpy ligands. Electrochemical studies of the X-CN-py ligands indicated that 2-CN-py and 4-CN-py have one reversible 1e- reduction and 3-CN-py has one quasi-reversible reduction. 4-CN-py is more easily reduced than 2-CN-py. EPR experiments on [2-CN-py]1- and [4-CN-py]1- combined with DFT calculations have indicated that the semi-occupied molecular orbital (SOMO) is delocalised over the entire molecule. The complex [Pt(4-CN-py)2Cl2] undergoes two reversible 1e- reductions, attributed to the sequential reduction of the two 4-CN-py ligands. [Pt(3-CN-py)2Cl2] was found to exhibit one irreversible reduction. The electrochemistry of the X,X´-(CN)2-bpy ligands indicated that 3,3´-(CN)2-bpy and 5,5´-(CN)2-bpy have two reversible 1e- reductions while 4,4´-(CN)2-bpy has only one reversible 1e- reduction. The reductions of 5,5´-(CN)2-bpy occur at significantly less negative potentials than those in 3,3´ or 4,4´ analogue. In-situ UV/Vis/NIR and EPR experiments on the X,X´-(CN)2-bpy ligands indicate that the reduction electron is delocalised over both the CN-py rings with the SOMO being spread across the entire molecule. [Pt(3,3´-(CN)2-bpy)Cl2] and [Pt(5,5´-(CN)2-bpy)Cl2] undergo two reversible 1e- reductions, attributed to the sequential reduction of the X,X´-(CN)2-bpy ligand. 4,4´-(CF3)2-bpy and 5,5´-(CF3)2-bpy, whose X-ray crystallographically determined structures are reported, both have one reversible 1e- reduction while 3,3´-(CF3)2-bpy exhibits an irreversible reduction. Again the 5,5´ analogue is the most easily reduced. Spectroelectrochemical results indicate that the reduction electron enters a SOMO that is delocalised over both the CF3-py rings. Substitution in the 5,5´ positions is determined to be electronically most significant. Complexes of the general formula [Fe(II)(X2-bpy)3][BF4] (where X = CN or CF3 in the 4,4´ or 5,5´ positions) exhibit three reversible ligand based reduction processes and a metal based oxidation. UV/Vis/NIR and EPR studies have confirmed that the reduction electron in each case enters a molecular orbital that is predominantly based on a bpy ligand. The redox potentials of 4-CN-py and 5,5´-(CN)2-bpy are solvent dependent with 1e- reduction of 4-CN-py and the two 1e- reductions of 5,5´-(CN)2-bpy moving to less negative potentials as the acceptor number (AN) of the solvent increases. A computational model has been developed for the study of the electronic properties of substituted bipyridines using DFT methods. This model has been used to aid the analysis of the EPR and UV/Vis/NIR spectra of the X2-bpys studied.

Over recent years, the application of assisted reproductive techniques in the treatment of infertility has increased exponentially, yet these methodologies still remain inherently inefficient. It has long been established that the single greatest obstacle to improving the success of these treatments is determining the quality of the oocytes used. However, currently the methods available for oocyte assessment are mainly qualitative, and suffer due to a lack of standardisation. As such, the efficiency of fertility treatments could benefit from the introduction of a rigorous quantitative measure of oocyte quality and maturation. The principal aim of this thesis was to determine the potential of Raman spectroscopy when applied to the field of oocyte biology. Consequently, this thesis addressed three main areas of investigation: I. the intra-oocyte biochemical variation; II. the biochemistry of oocyte maturation; and finally, III. the effect of environment on the mature oocyte in vivo and in vitro. I. To investigate the presence of intra-oocyte biochemical variation, oocytes from various stages of development were analysed using high resolution Raman mapping, in combination with univariate and multivariate analysis. Images revealed variation between the germinal vesicle and ooplasm in immature oocytes, as well as intra-ooplasmic variation in all oocytes. II. The spectral analysis of oocytes derived from pre-antral and in vitro cultured follicles revealed significant variation: It was found that Raman spectroscopy could successfully discriminate between immature and mature oocytes. III. Finally, the spectral analysis of oocytes derived from unstimulated and stimulated ovulation cycles, as well as those derived from in vitro follicle cultures, revealed that although biochemically similar, in vitro matured oocytes demonstrated reduced protein content. Furthermore, greater spectral variation was observed in superovulated oocytes, which was found to describe the corresponding morphological quality. In conclusion, this thesis has demonstrated the effective application of Raman spectroscopy to the study of fixed murine oocytes. Raman mapping experiments have demonstrated this technique for the visualisation of biochemical variation which exists within the oocyte. Furthermore, using Raman spectroscopy, the identification of the biochemical variation resulting from different maturation mechanisms has been achieved, as has the discrimination of immature and mature oocytes. These results indicate that Raman spectroscopy holds promise as a quantitative analysis method in the field of fertility treatment.

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Approximately 450 000 people have diabetes in Sweden today, and the number of diabetics only rises. Monitoring blood sugar several times a day is a fundamental part of managing the disease, and reducing the risks of complications. Today’s glucose monitoring devices are invasive and require small needle sticks for a measurement. Providing a painless method of monitoring the blood sugar level would relieve the lives of diabetics world-wide.   The objective of this project was to investigate the absorption spectra of aqueous glucose concentrations (100 to 5000 mg/dl) in the mid infrared region with Fourier Transform spectroscopy (FTIR), and finally implementing a hand-held monochromatic spectrometer to demonstrate a non-invasive concept. The method chosen for implementing the hand-held demo is due to the commercial availability of diodes and detectors at those wavelengths.   The results from the FTIR showed a trend among concentrations in all wavelengths, in between 1180 to 980 cm-1, specifically at 1035 cm-1, but also in the region 2920 to 2850 cm-1. The hand-held spectrometer did not register any transmittance of the glucose samples. For future implementations, 1035 cm-1 should be investigated more in-depth for a hand-held device.

A low-cost fibre-optic probe was constructed, and used to provide an optical link between an FT-Raman spectrometer and a Differential Scanning Calorimeter (DSC). The resulting Simultaneous Raman-DSC (SRD) method combines the vibrational structural information of FT-Raman spectroscopy with the thermal data of DSC, which is particularly useful for characterisation of samples exhibiting temperature- and thermal conditioning-dependent polymorphic (i. e. structural) changes. The samples chosen for method development and structural study were ammonium nitrate (NH4NO3), the triglyceride sn-1,3-distearoyl-2-oleoyl glycerol (SOS), cocoa butter (which is chiefly composed of a mixture of monounsaturated triglycerides), and some chocolates of differing composition. The bifurcated `6-around-i' parallel fibres probe design allowed Raman spectra to be collected from unencapsulateds amplesi n the normal DSC sample position without extensive mechanical modifications or the use of extra optical components. Method development using the above samples showed that the combined SRD sampling has various effects on collected data. With this probe design, a "glass background" spectrum is superimposed on the Raman spectrum, and must be subtracted using the spectrometer software. At raised temperatures, a thermal emission feature appears in the Raman spectrum at high wavenumber shift. The incident laser light was found to raise sample temperatures by around 1.5-3K. Raman spectra were therefore collected with samples held around 10K below transition onset temperatures. The necessary lack of encapsulation resulted in broadened thermal transitions in DSC heating curves, and potential heat loss due to radiative emission at raised temperatures. However, for samples analysed near room temperature, onset melting points for transitions with the laser off were not significantly altered by SRD sampling. Ammonium nitrate is often irreproducible in it's exact phase transition thermal behaviour. SRD analysis showed the expected phases IV, III, II and I at room temperature and above at normal atmospheric pressure. Raman spectra could then be unambiguously assigned to the respective phases. Comparison with previous literature work allows the spectral changes seen to be interpreted using symmetry-based rationalisations. The triglyceride SOS was found to conform well to the literature thermal behaviour. SRD analysis showed DSC heating curves with onset melting points and features identifying the polymorphs produced as a, , y, ß', ß2 and [il. A literature survey allows the corresponding Raman spectra to be interpreted in the light of structural packing suggestions made by workers using various other analytical techniques. Cocoa butter was successfully prepared in states 3,4,5 and 6 of the six polymorphs known to exist. DSC melting behaviour and heating curve shapes were used to unambiguously relate Raman spectra to the individual polymorphs. Interpretation of Raman spectra was based on the SOS triglyceride SRD results, together with structural packing suggestions from the literature. A selection of chocolate samples were also analysed by SRD. Those with a high cocoa butter content were found to approximate well to the thermal and structural behaviour of pure cocoa butter.

No description available.