When biomagnetic separation is used in production processes, quality control becomes a priority. The first step is to define and validate the process, but then the key point is checking the repeatability of every single batch.
The purposeof monitoring a biomagnetic separation is to obtaina record of different processesto be able to compare the results. Using homogenous magnetic force, changes can easily be related toany modifications made tothe suspension. Changes tothe magnetic bead specifications(diameter, magnetic moment), concentration, andvariations in buffer viscosity suggest different separation process dynamics.
The traditional way to check whether a Biomagnetic Separation Production process is complete is by sight. The technician/researcher looks at the suspension. At the beginning of the process the suspension is homogenous and opaque. When the separation process is complete, the magnetic beads are left on the walls of the vessel and the supernatant is transparent. When the suspension is ‘transparent’, the technician stops the process by extracting the supernatant, leaving the magnetic beads in the bottle. After repeating the same process several times, a separation time can be defined and used as a benchmark. With the traditional method, the only quality control record is the OK/no OK signed by the person handling the vessel with no supporting data. In case of a quality issue with the product, this may not be detected until a later stage, and there is no data to show whether the problem occurred before, during or after the biomagnetic separation.
One of the problems of working with small tubes and classical magnetic separators (or simple magnets) is the lack of definition of the magnetic force. As the magnetic field and its gradient changes with distance, the force on the magnetic beads is not constant and variations in the behavior of the suspension are difficult to interpret.
The standardmethodfor developing and validatingBiomagnetic separation processes is sampling the supernatant at different times. This sample is usually measured using a spectrophotometer. Bead concentration is determined by selecting the right wavelength to avoid interferences with the biomolecules presents in the buffer and comparing it with a calibration curve. The separation time is selected when the number of beads approaches zero. Magnetic susceptibility using the fundamental frequency or some of its harmonics has recently been proposed as alternative.
It is hardly breakingnewsthat separation technologyis one of the most complex and important areas of biotechnology. Finding cost-effective separation techniques is a crucial factor forthe growth of industrial biotechnology. Not only is it necessary at the application point (diagnostics, protein purification, cell sorting) but also to facilitate large-scale production.
The apparentlysimple nature of the biomagnetic separation process is the reason for its great popularity in Life Science, but it is also one the causes behind problems with its proper application. All usersare aware of the working principle: the magnetic field applied generates a force over the magnetic beads or particles. It is very simple to perform a quick feasibility test: just take a small quantity of magnetic carriers in suspension, approach a magnet and – Voilà! – the beads/particles will speed towards the magnet.