Particle electrophoresis for quality assurance and process control.

Process control is an increasingly important issue as life science companies world-wide strive for recognition of their manufacturing and product development quality measures according to International Standards Organization (ISO) or good manufacturing practices (GMP) standards. Analytical particle electrophoresis (APE) has the potential for significant contributions, not just to basic research, but also in process development and control in manufacturing environments. An important feature of colloidal (small) particles, which controls their behavior, is their surface charge. Optimization of life science products and process conditions involving small particles (>100 nm) may be approached by a variety of strategies based upon direct measurements of the charge properties of process particles or "reporter" particles. The availability of increasingly powerful instruments and control particle preparations (National Institute of Standards and Technology ((NIST) and others) for validation of instrument operation make the method more attractive than ever. We summarize highly flexible electrophoretic strategies for assessing process consistency both from the perspective of particles being processed as well as the processing environment and describe principles for the use of polymer microspheres both as control particles for validation of instrument operation as well as for probes of the assay medium.