Virus recovery by tangential flow filtration: A model to guide the design of a sample concentration process

A simple model is developed to describe the instantaneous (r_v ) and cumulative (R_v ) recovery of viruses from water during sample concentration by tangential flow filtration in the regime of constant water recovery, r. A figure of merit, M = r_v r, is proposed as an aggregate performance metric that captures both the efficiency of virus recovery and the speed of sample concentration. We derive an expression for virus concentration in the sample as a function of filtration time with the rate-normalized virus loss, $$ , as a parameter. A practically relevant case is considered when the rate of virus loss is proportional to the permeation-driven mass flux of viruses to the membrane: $$ . In this scenario, the instantaneous recovery is constant, the cumulative recovery is decreasing as a power function of time, $$ , η mediates the trade-off between r and r_v , and M is maximized at $$ . The proposed model can guide the design of the sample concentration process and serve as a framework for quantification and interlaboratory comparison of experimental data on virus recovery.