UV-VIS spectra as potential process analytical technology (PAT) for measuring the density of compressed materials: Evaluation of the CIELAB color space.

Measurement methods for determining the density of compressed materials, being a critical quality attribute, provide an important parameter for successful processing. In this study, a novel approach was developed for determining the density of compacts using ultraviolet-visible spectrophotometry. The assumption within this context was that a change in density affects the corresponding color information of the compact. From the obtained spectra of the visible range, the color information of the compact was calculated which turned out to be directly proportional to the density of the compact. In comparison, the obtained spectra were analyzed using partial least square regression. The results of this study showed that both methods could be used predicting the density of a compact from the corresponding visible spectrum at identical accuracy. In contrast to the partial least square regression, the correlation of the color information as a direct output parameter of the spectrophotometer with the density required no excessive data pre-processing. Subsequently, the easier and faster data processing of the color information over the partial least square regression, conceives using this novel approach as potential process analytical technology tool for implementation into a compression process e.g., tableting or roller compaction.

Novel ultrasonic in-die measurements during powder compression at production relevant speed.

A novel ultrasonic instrumentation was successfully implemented in a compaction simulator. A through-transmission set-up was realised with longitudinal and transverse transducers being alternately positioned inside Euro-D-modified punches. Key features of the data acquisition are described. Considerable attention was paid to an accurate displacement measurement and a synchronic acquisition of the ultrasonic signal. Vivapur 102 and Di-Cafos A150 were chosen for evaluation. In contrast to other published instrumentations, production-relevant powder densification speeds were feasible whilst featuring outstanding measurement precision. Maximum ultrasonic speed was achieved at maximum density. Materials differed considerably regarding the slope of the decompression phase, which might be suitable for assessing elasticity and speed sensitivity of powders or formulations without compressing twice. The developed set-up furthermore enables in-die measurements of apparent Young's modulus and apparent Poisson's ratio (i.e. their change throughout the course of the tableting process). Young's modulus increased upon densification and values match with literature data. Poisson's ratio increased linearly as a function of solid fraction for plastically deforming Vivapur 102, whereas it was practically constant for brittle Di-Cafos A150. Increased mechanistic understanding of deformation factors (e.g. rearrangement, fragmentation, elasticity) and estimation of mechanical compatibility of mixtures, is feasible. Moreover, in-die Young's modulus and Poisson's ratio are valuable for compression simulations based on finite or discrete element method.

Multidimensional monitoring of anaerobic/aerobic azo dye based wastewater treatments by hyphenated UPLC-ICP-MS/ESI-Q-TOF-MS techniques.

Sulfonated reactive azo dyes, such as Reactive Orange 107, are extensively used in textile industries. Conventional wastewater treatment systems are incapable of degrading and decolorizing reactive azo dyes completely from effluents, because of their stability and resistance to aerobic biodegradation. However, reactive azo dyes are degradable under anaerobic conditions by releasing toxic aromatic amines. To clarify reaction mechanisms and the present toxicity, the hydrolyzed Reactive Orange 107 was treated in anaerobic-aerobic two-step batch experiments. Sulfonated transformation products were identified employing coupled ICP-MS and Q-TOF-MS measurements. Suspected screening lists were generated using the EAWAG-BBD. The toxicity of the reactor content was determined utilizing online measurements of the inhibition of Vibrio fischeri. The OCHEM web platform for environmental modeling was instrumental in the estimations of the environmental impact of generated transformation products.