RESUMEN
The excellent compatibility of polyol esters (POEs) with general fluids coolants such as CO(2) and non-chlorinated coolants (e.g. hydrofluorocarbons, HFCs) in terms of solubility, miscibility and chemical stability has fostered their use as lubricants by the refrigeration industry. The most widely used POEs bases consist of esters of polyalcohols - such as pentaerythritol, dipentaerythritol and neopentylglycol - with mixtures of carboxylic acids of 4-10 carbon atoms. Their thermophysical properties (viscosity mainly) are crucial with a view to producing efficient lubricants for specific applications. Usually, POE formulations, which usually contain several bases, are characterized in terms of global indices. In this work, we developed a methodology based on NIR spectroscopy for the characterization and analysis of lubricant formulations. The products, including lubricant bases and lubricant formulations, are characterized by reference to two spectral libraries that are used to identify as the starting lubricant bases as well as the lubricant formulations. It has been proposed to build libraries in cascade for the differentiation of lubricant formulations without and with low content in additives. Once the identification of the formulation is applied PLS multivariate models are used to determine the components of a lubricant formulation and its viscosity.
RESUMEN
Herbicide preparations, which typically consist of an active compound and an adjuvant, are formulated in such a way as to facilitate rapid dispersion of the pesticide and its transfer across the fat cuticle of plant leaves. The adjuvant usually comprises various substances including an oil, water, and one or more emulsifiers for increased stability. The difficulty of analyzing these mixtures has severely restricted the ability to control herbicide preparations, which must usually be characterized in terms of global, non-specific parameters such as the acid, saponification, and hydroxyl values. Near-infrared spectroscopy is an expeditious analytical technique requiring no sample preparation and affording multi-determinations in complex mixtures. In this work, we used laboratory-made samples to construct PLS multivariate models for determining the components of the adjuvant mixture in a herbicide preparation. The best ensuing model was validated and used to analyze industrial preparations with good results.
RESUMEN
Cosmetic preparations typically consist of mixtures of various compounds of natural origin or their derivatives. Their analysis is made rather difficult by their usually high complexity and is utterly impossible with a single analytical method; also, there is usually little to be gained by determining every individual component of the mixture. Rather, analyses are aimed at ensuring a proper balance between the contents of each component and thus require the use of methods capable of delivering global information. The combined use of near-infrared (NIR) spectroscopy and multivariate spectral processing chemometric techniques has enabled the development of effective methods for establishing the composition of complex samples with acceptable levels of analytical properties, such as accuracy, precision and throughput. In this work, we developed partial least squares calibration models for the determination of each component in a cosmetic mixture, and global indices (viz. the hydroxyl value), simply from the NIR spectrum of the sample. The models thus obtained are accurate enough for use in quality control analyses of cosmetic preparations and provide an effective alternative to existing conventional global methods.
