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Objectively Quantifying the Separation Time of your Magnetic Bead Separation Process

The separation time in standard magnetic separation devices is usually determined by analyzing aliquots of solution taken at different times. The problem is that each aliquot gives the technician information about one spatial point in time. Therefore, the design of validation experiments becomes a very complex endeavor.

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Homogenous systems can be monitored, however, as a whole, allowing the technician to monitor all points at all times during the process. Monitoring the entire magnetic separation process provides an easy and objective quantification of the separation time parameter.

This post is about Magnetic Bead Separation in the production of magnetic beads for IVD kits. If you want to know its most important elements, download our free eBook The Basic Guide to use Magnetic Bead Separation in production processes:

The separation time is the time between when the vessel is placed inside the Magnetic Bead Separator and before the supernatant is pumped out. This is a practical value that should be followed by production technicians and that should be used in any standard operating procedure (SOP). But determining this value in classic, inhomogeneous magnetic separators is not straightforward. The magnetic beads move at different speeds at different points in the vessel. In order to determine an SOP for these inhomogeneous separators, it is necessary to sample the beads at different spatial points and times. This requires a complex and expensive validation experimental design for each individual product in order to have reliable results.

The benefits of homogenous Magnetic Bead separation conditions

In contrast, homogenous Magnetic Bead Separation conditions such as those provided by SEPMAG technology allow all beads to move at the same speed, since the force is constant over the entire working volume of the vessel. The bead front moves radially and can be easily monitored and quantified. Optical measurement can be accomplished over the entire suspension volume, eliminating the need for complex sampling protocols.

Monitoring systems such as the SEPMAG QCR provides a standard separation curve, making it much easier to quantify separation time. Since the curves are typically sigmoidal-like, the half separation time (t50) is the suggested ‘robust’ measurement. A direct measure at 99% separation is possible, but there is more signal noise, decreasing the accuracy of the measurement.

In practice, separations times that are 3-5 times greater than the half separation time will give > 99% recovery. If it is necessary for the purposes of validation, traditional sampling can be performed in order to fine tune the separation time. In homogenous Magnetic Bead Separation, because of the constant speed of bead movement and a standard protocol to determine the initial separation time, sampling experiments are straightforward and the size of validation experiments is minimized.

Monitoring homogenous Magnetic Bead Separation processes provides a robust way to determine and validate separation times both at small scale development and scaled up production processes.

If you found this post about using Magnetic Bead Separation for production useful, don’t forget to check these related posts:

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Lluis M. Martínez | SEPMAG Chief Scientific Officer

Founder of SEPMAG, Lluis holds a PhD in Magnetic Materials by the UAB. He has conducted research at German and Spanish academic institutions. Having worked in companies in Ireland, USA and Spain, he has more than 20 years of experience applying magnetic materials and sensors to industrial products and processes. He has filed several international patents on the field and co-authored more than 20 scientific papers, most of them on the subject of magnetic particle movement.

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