Over the last decade Fourier transform infrared (FT-IR) and near-infrared (NIR) spectroscopic imaging with focal plane array (FPA) detectors have proved powerful techniques for the rapid visualization of samples by a combination of spectroscopic and spatial information. Using these methods, selected sample areas can be analyzed with reference to the identification and localization of chemical species by FT-IR spectroscopy in the transmission or attenuated total reflection (ATR) mode and by NIR spectroscopy in diffuse reflection with a lateral resolution in the micrometer range. The present communication focuses on the quantitative determination of the active ingredient composition of a solid drug formulation by NIR spectroscopic imaging with a focal plane array detector and the results obtained are compared to the quantitative data obtained by conservative light-fiber NIR spectroscopic diffuse reflection measurements with a single-element detector. The communication also addresses the issue of penetration depth of NIR radiation into the investigated solid material.
all rights reserved Vodka (from russian voda = water) is a very popular alcoholic beverage and nowadays is produced not only in russia but in many countries all over the world. In the european union (eu), vodka is defined by law to be a spirit drink produced from ethyl alcohol of agricultural origin obtained by fermentation with yeast from either (i) potatoes and/or cereals, or (ii) other agricultural raw materials, followed by distillation and rectification so that the organoleptic characteristics of the raw materials used and by-products formed in the fermentation are selectively reduced. this process may be followed by redistillation and/or treatment with appropriate processing aids, including treatment with activated charcoal, to give it special organoleptic characteristics. If vodka is not produced exclusively from potatoes or cereals, the raw materials have to be indicated on the bottle label (for example, in the case of alcohol from sugar-beet, sugar-cane molasses or grapes). 1 differences in the composition of vodka may not only arise from the raw materials used for the alcohol production but also from the quality of water, which is used to re-dilute the distillate to drinking strength. for premium vodka brands, demineralised water is filtered through activated carbon to absorb unwanted organic and inorganic materials. then it is passed through deionisation columns, which remove other impurities. 2 after bottling, the vodka will remain stable for many years if very well demineralised water is used. otherwise, an increased content of calcium, magnesium or other compounds The objective of this study was to determine the potential of using near infrared (NIR) transmission spectroscopy to build calibration models for the quantitative characterisation and qualitative discrimination of Russian and non-Russian (foreign) vodkas. The results of partial least squares models based on the NIR spectra of 109 vodka samples showed that the major constituent alcoholic strength [root mean square error of prediction (RMSEP) 0.25% vol] and the physical parameter relative density (RMSEP 0.0003) could be successfully determined quantitatively. The method failed, however, in quantifying certain minor components such as anions, cations and sugars. For qualitative discrimination, soft independent modelling of class analogy analysis (SIMCA) and linear discriminant analysis (LDA) were applied to the sample set containing both the Russian and the foreign vodkas. Despite the correct assignment of unknown test samples to the respective vodka species, both modelling approaches, however, did not prove reliable enough for unambiguous authentication purposes.
Fourier transform near-infrared (FT-NIR) diffuse reflection spectroscopy was used in combination with principal component analysis and partial least-squares regression to simultaneously determine the physical and the chemical parameters of a porous poly(p-methylstyrene-co-1,2-bis(p-vinylphenyl)ethane) (MS/BVPE) monolithic polymer. Chemical variations during the synthesis of the polymer material can alter the pore volume and pore area distributions within the polymer scaffold. Furthermore, mid-infrared and near-infrared (NIR) spectroscopic chemical imaging was implemented as a tool to assess the uniformity of the samples. The presented study summarizes the comparative results derived from the spectral FT-NIR data combined with chemometric techniques. The relevance of the interrelation of physical and chemical parameters is highlighted whereas the amount of MS/BVPE (%, v/v) and the quantity (%) of micropores (diameter, d < 6 nm), mesopores (6 nm < d < 50 nm), and macropores (50 nm < d < 200 nm) could be determined with one measurement. For comparison of the quantitative data, the standard error of prediction (SEP) was used. The SEP for determining the MS/BVPE amount in the samples showed 0.35%, for pore volume quantiles 1.42-8.44%, and for pore area quantiles 0.38-1.45%, respectively. The implication of these results is that FT-NIR spectroscopy is a suitable technique for the screening of samples with varying physicochemical properties and to quantitatively determine the parameters simultaneously within a few seconds.
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