PubMed · 5019017
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F Wetzel. 1972-02-29. [Ointment syringe].. https://pubmed.ncbi.nlm.nih.gov/5019017/
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A bead injection spectroscopy-flow injection analysis (BIS-FIA) system for the spectrophotometric detection of promethazine and trifluoperazine is developed. The sensor is based in the oxidation of the phenothiazines by Fe(III) which is later determined by formation of the complex between Fe(II) and Ferrozine, [FeFz(3)](4-). Immediately, this complex is retained on a homogeneous bead suspension of Sephadex QAE A-25 resin (500 microl) which has been injected previously in the system to fill a commercial flow-cell (Hellma 138-OS). The use of BI with respect to the use of a reusable flow-through sensor is justified because the complex is so strongly retained on the beads that the regeneration of the solid support becomes extraordinarily difficult in the proposed method. At the end of the analysis, beads are automatically discarded from the flow-cell, by reversing the flow, and transported out of the system. The analytical signals are measured at a wavelength of 567 nm, corresponding to the absorbance of the complex. Using a sample volume of 600 microl, the analytical signal showed a very good linearity in the range 0.5-8.0 microgml(-1) and 0.5-10.0 microgml(-1), with detection limits of 0.09 and 0.14 microgml(-1) for promethazine and trifluoperazine, respectively. R.S.D.s (%) lower than 2% were obtained for both analytes. The proposed method is highly selective in the presence of other species that are normally encountered with these analytes. The sensor was satisfactorily applied to pharmaceutical preparations.
This study was performed to elucidate the influences of process and formulation design using power consumption and temperature measurements during granulation. Power consumption was recorded "in process" using a previously introduced computer program for optimal end-point detection at an early stage. The temperature increase (DeltaT) during granulation was recorded using a temperature sensor. The temperature increase in the wet powder bed expresses the friction forces at interparticle contacts occurring during granulation. The maxima of temperature profile occurred at 130% saturation, whereas the maxima of power consumption were determined at 100% saturation. The ratio of temperature and power consumption (TPR factor) is introduced as a signature of formulation design. TPR factor was found to be dependent on particle size, particle surface, water absorption capacity and solubility of the excipient and model drug, respectively. However, TPR factor was found to be independent of process design, such as the filling level of the mixer. Understanding and controlling the granulation process is a key factor in robust dosage form design. The "in process" control fits ideally the prerequisites of a drug quality system for the 21st century and FDA's Process Analytical Technology (PAT) initiative. The results of previous and present works of our research group will be used in a following step to develop an artificial neural network for granulation "in process" control.
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