Predicting calcium in grape must and base wine by FT-NIR spectroscopy

Calcium content in sparkling wines may not exceed 80 mg/L due to the risk of aggregation with alginate capsules. The high calcium content usually found in wine and must emphasizes the need to develop alternative and appropriate techniques faster and cleaner than atomic absorption spectrometry (AAS). To obtain a robust model to predict calcium content, FT-NIR spectroscopy was used in 98 base white wine samples and 60 must samples from an Alentejo winery. The reference method for calcium determination was AAS technique, with a dry ashing sample procedure, as a prior treatment. Results confirmed the ability of FT-NIR as an alternative technique to AAS, to predict calcium content in grape must and base wine. Advance knowledge of the calcium content in the grape must will help avoid obtaining a mixture of musts with a high calcium content in the same container

Characterization of heavy oil fractions using spectrometric techniques

The work presented in this thesis was focused on developing spectroscopic techniques that can be easily incorporated in an instrument for the rapid characterization of heavy oil fractions. Transmission infrared, attenuated total reflectance infrared, visible, and nuclear magnetic resonance spectroscopy were the techniques studied in the course of this project. The key properties of the heavy petroleum fraction that were characterized are as follows: Viscosity parameter: Viscosity at 210 and 100 °F, Viscosity Index Compositional: Relative percentage content of paraffin, naphthene, and aromatic Optical: Color of the heavy oil fraction The techniques developed in this project would reduce the labor and maintenance involved in the quality control labs in the industry. The time scale of characterization by these techniques is of the order of 4 minutes and hence, the results can be used more effectively for process feedback. This is in stark contrast to the time taking characterization techniques prevalent in the industry. The following are the outcome of the project: The transmission Infrared (IR) is inappropriate for predicting the heavy oil properties Attenuated Total Reflectance (ATR) Infrared (IR) measurement is better for the present purposes Predictions o key viscosity parameters of the heavy oil fraction (Viscosity at 100 and 210°F, and Viscosity Index) based on ATR IR measurements are good ATR IR spectra also correlated well with the compositional properties (percentage paraffin, naphthene,and aromatic) of the heavy oil fractions derived from the Nuclear Magnetic Resonance (NMR) spectra of the oil fractions For color characterization, IR spectrum was found inadequate. Visible spectra of the samples was found to be more useful for color characterization The findings from the project suggest that a combination of ATR IR and visible spectroscopic measurement techniques can successfully characterize the properties of heavy oil fractions. In future, these methods of analysis can be formalized into procedures transferable to a prototype analyzer

Investigating of the conservation problems of oil paintings on paper supports

The initial results of a research project on the investigation of problems presented by a collection of oil paintings on paper supports are presented. The project focuses on the effect of the oil medium on the deterioration of cellulose, on the materials and techniques used by the artists and on comprehension of the resulting problems. Non destructive methodology was used to record the behaviour of the materials when examined in several regions of the electromagnetic spectrum which gives an indication of areas of damage. . Various analytical techniques were applied to investigate the painting materials and supports in original works of art. The increase in rate of the oxidation of cellulose in paper, when the paper is coated in oil, is investigated by analyzing volatile organic compounds emitted during ageing tests. The assessment of the results obtained will act as a pilot for a more extensive program of research, the ultimate aim of which is the formulation of a recommended methodology as a tool for the evaluation of the condition of these types of works, as well as the determination of conservation and care parameters

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

The Role of UV-Visible Spectroscopy for Phenolic Compounds Quantification in Winemaking

Phenolic compounds are bioactive substances present in a large number of food products including wine. The importance of these compounds in wine is due to their large effect on the organoleptic attributes of wine. Phenolic compounds play a crucial role in the colour as well as mouthfeel properties of wines. UV-visible spectroscopy appears as a suitable technique for the evaluation of phenolic compounds’ properties and content. The ability of the phenolic ring to absorb UV light and the fact that some of the phenolic substances are coloured compounds, i.e. show absorption features in the visible region, make UV-visible spectroscopy a suitable technique to investigate and quantify grape and wine phenolic compounds. A number of analytical techniques are currently used for phenolic quantification. These include both simpler approaches (spectrophotometric determinations) as well as more complex methodologies such liquid chromatography analysis. Moreover, a number of spectroscopy applications have also been recently reported and are becoming popular within the wine industry. This chapter reviews information on the UV-visible spectral properties of phenolic compounds, changes occurring during wine ageing and also discusses the current UV-visible based analytical techniques used for the quantification of phenolic compounds in grapes and wine

Synthesis and Characterization of Humic/Melanin-like Compounds by Oxidative Polymerization of Simple Aromatic Precursors

Dissolved organic matter (DOM) is a complex mixture of naturally occurring organic molecules originating from multiple marine and terrestrial sources. DOM plays a significant role in water quality by affecting the photochemistry, trace metal transport, and acidity in aquatic systems. Understanding the chemical composition of DOM helps interpret the links between its optical properties and molecular structures. Currently, the molecular origins of the optical properties of DOM are not well-defined. In this study, we oxidize and initiate the polymerization of melanin precursors 1,8-dihydroxy naphthalene and 5,6-dihydroxy indole by the addition of hydrogen peroxide and/or with ultraviolet irradiation. Our goal is to evaluate the possibility of reproducing the optical signatures of DOM from simple aromatic precursors. Optical characterization shows an extreme shift of the absorbance to a featureless trend and broad fluorescence peaks (350–500 nm) like DOM. Electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) mass spectrometry show evidence of oligomers with varying degrees of oxidation. The combination of our results shows that about 1–4 units of melanin oligomers with varying degrees of oxidation mimic the optical properties of DOM. Overall, our results strongly support the idea that simple precursors form oligomeric chromophores mimicking DOMs optical properties through simple oxidative steps

Optoacoustic spectrometry for small solid and liquid samples

Imperial Users onl

Thermochromism of Model Organic Aerosol Matter

Laboratory experiments show that the optical absorptivity of model organic matter is not an intrinsic property, but a strong function of relative humidity, temperature, and insolation. Suites of representative polyfunctional C_(x)H_(y)O_(z) oligomers in water develop intense visible absorptions upon addition of inert electrolytes. The resulting mixtures reach mass absorption cross sections σ(532 nm) ~ 0.1 m^(2)/gC in a few hours, absorb up to 9 times more solar radiation than the starting material, can be half-bleached by noon sunlight in ~ 1 h, and can be repeatedly recycled without carbon loss. Visible absorptions red-shift and evolve increasingly faster in subsequent thermal aging cycles. Thermochromism and its strong direct dependences on ionic strength and temperature are ascribed to the dehydration of >CH−C(OH)C═C< unsaturations by a polar E1 mechanism, and bleaching to photoinduced retrohydration. These transformations are deemed to underlie the daily cycles of aerosol absorption observed in the field, and may introduce a key feedback in the earth’s radiative balance

Novel chemical and toxicological studies on textile industry waste streams clean up

The textile industry is a major water consumer and producer of effluent waste water. A comprehensive review of the literature shows an urgent need to improve the treatment of dyeing and finishing plant effluent. To destroy dyes and purify dye house effluents modem photochemical oxidation methods, such as the UV /hydrogen peroxide process, provide an effective treatment technology. Organic contaminants can be completely mineralised by this method but it is relatively expensive. Photochemical oxidation with subsequent microbiological treatment appears an attractive and cost effective approach in textile waste water treatment. This research studied the feasibility of combining UV /hydrogen peroxide photochemical oxidation with microbiological treatment to destroy organic dyes and to decolourize waste water. Experiments on the decolourization of a number of mono- and disazo dyes by UV/oxygen and hydrogen peroxide as a function of initial concentration of dyes, dissolved oxygen and hydrogen peroxide, alkalinity and temperature of solutions were carried out. UV /hydrogen peroxide photochemical treatment was shown to rapidly decolourize and decompose organic azo dyes. Increase in oxidant concentration to give a molar ratio between hydrogen peroxide and dye concentrations of 200/1 was found to increase the decolourization rate. Changes in pH to acidic and alkaline also increase dye decolourization rate, the highest decolourization was observed at pH 10.5. Increase in the temperature from 25°C to 60°C slightly increases decolourization rate. Chromatographic, spectrophotometric and mass-spectrometric techniques were used to elucidate breakdown pathways and identify intermediates. Suggested type of photo-degradation is destructive oxidation involving rapid breakdown of the azo group with the formation of colourless intermediate substances such as naphthalene (naphthoquinone) and benzene (phenol) derivatives. These intermediates do not accumulate and are further photo-degraded to lower molecular weight substances, organic acids. Work on establishing ecotoxicological effects and biodegradability of dyes and their photochemical breakdown products, with particularly reference to micro-organisrns, was carried out with the biological tests using the freshwater green alga Chlorella vulgaris, the bacterium Pseudomonas putida and activated sludge. Photochemical treatment of dye solutions with UV/oxygen or UV irradiation alone does not eliminate their toxicity. When the UV /hydrogen peroxide system was used decolourized solutions were non-toxic to microorganisms. Activated sludge is slow and inefficient in removing residual colour from the dye solutions partially decolourized by photo-oxidation, generally removal of residual colour was in the range of 82 - 85.5 % after 72 hours of biotreatment. An increase in biochemical treatment time from 24 to 144 hours also did not have an influence on colour removal. With an increase in preliminary photochemical treatment time susceptibility of the dye solutions to the biochemical action of activated sludge increases. The combination of the UV /hydrogen peroxide process with subsequent microbiological treatment is a satisfactory treatment for azo dye solutions suitable for commercial application. Further research to extend the application to other dye classes, particularly reactive dyes In justified