Use of Microfluidic Capillary Electrophoresis for the Determination of Multi-Component Protein Adsorption Isotherms: Application to High-Throughput Analysis for Hydrophobic Interaction Chromatography.

Chromatography is a widely used separation process for purification of biopharmaceuticals that is able to obtain high purities and concentrations. The phenomena that occur during separation, mass transfer and adsorption are quite complex. To better understand these phenomena and their mechanisms, multi-component adsorption isotherms must be investigated. High-throughput methodologies are a very powerful tool to determine adsorption isotherms and they waste very small amounts of sample and chemicals, but the quantification of component concentrations is a real bottleneck in multi-component isotherm determination. The behavior of bovine serum albumin, Corynebacterium diphtheriae CRM197 protein and lysozyme, selected as model proteins in binary mixtures with hydrophobic resin, is investigated here. In this work we propose a new method for determining multi-component adsorption isotherms using high-throughput experiments with filter plates, by exploiting microfluidic capillary electrophoresis. The precision and accuracy of the microfluidic capillary electrophoresis platform were evaluated in order to assess the procedure; they were both found to be high and the procedure is thus reliable in determining adsorption isotherms for binary mixtures. Multi-component adsorption isotherms were determined with a totally high-throughput procedure that turned out to be a very fast and powerful tool. The same procedure can be applied to every kind of high-throughput screening.

On the Use of Infrared Thermography for Monitoring a Vial Freeze-Drying Process.

Monitoring a vial freeze-drying process without interfering with product dynamics is a challenging issue. This article presents a novel device constituted by an infrared camera designed to be placed inside the drying chamber, able to monitor the temperature of the vials, very close to that of the product inside. By this way it is possible to estimate the ending point of the primary drying, the heat transfer coefficient to the product (Kv), and the resistance of the dried product to vapor flux (Rp). Experiments were carried out in a pilot-scale freeze-dryer, processing 5% and 10% sucrose solutions at different values of shelf temperature and chamber pressure, using both thermocouples and the IR camera to track product dynamics. Results evidence that the measurements (of temperature) and the estimates (of the ending point of the main drying and of Kv and Rp) obtained using the 2 systems are very close, thus validating the IR camera as an effective process analytical technologies for the freeze-drying process. Besides, it was shown that the presence of the IR camera in the chamber is not responsible for any additional heating to the product and that monitored vials are representative of the majority of the vials of the batch.