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5 L DI water flush 9:10 0.5 24 10 0 0.17 22 14 17 102
1 L 0.1N NaOH total recycle 9:20 0.5 24 10 0 0.17 22 14 17 102
Normalized Flux testing 9:50 0.5 24 10 0 0.17 22 14 17 102
Integrity testing 10:00 30 0.001 1 L
Equilibration buffer recycle 10:10 0.5 25 10 0 0.15 22 15 17.5 90

Process: Starting Feedstock Volume = 4 L at 2 g/L
Step Time Run Time Feed Rate Pfeed Pret Pfilt Filt. Rate Filt Vol. Temp DP TMP Flux
[hh:mm] [min] [L/min] [psig] [psig] [psig] [L/min] [L] [°C] [psid] [psid] [L/m2 h]

J v T, Q1, C =2 g/L 10:20 0.7 33 7 0 0.108 22 26 20 65

10:30 0.7 43 17 0 0.152 22 26 30 91
10:40 0.7 63 37 0 0.196 22 26 50 118
J v T, Q2, C = 2 g/L 10:50 0.5 17 3 0 0.042 22 14 10 25

11:00 0.5 27 13 0 0.087 22 14 20 52
11:10 0.5 37 23 0 0.125 22 14 30 75
11:20 0.5 47 33 0 0.147 22 14 40 88
11:30 0.5 57 43 0 0.155 22 14 50 93
J v T, Q3, C = 2 g/L 11:40 0.3 13 7 0 0.032 22 6 10 19

11:50 0.3 23 17 0 0.065 22 6 20 39
12:00 0.3 33 27 0 0.092 22 6 30 55
Conc to C = 20 g/L 12:10 0 0.5 37 23 0 0.125 0 22 14 30 75

12:27 17 0.5 37 23 0 0.110 2 22 14 30 66
12:43 33 0.5 38 23 0 0.088 3.6 22 15 30.5 53
12:47 37 0.5 40 23 0 0.073 3.2 22 17 31.5 44
J v T, Q2, C = 20 g/L12:57 0.5 17 3 0 0.025 22 14 10 15

1:07 0.5 27 13 0 0.052 22 14 20 31
1:17 0.5 37 23 0 0.073 22 14 30 44
1:27 0.5 47 33 0 0.080 22 14 40 48
Post-Use Cleaning
Step Time Feed Rate Pfeed Pret Pfilt Filt. Rate Temp DP TMP Flux
[hh:mm] [L/min] [psig] [psig] [psig] [L/min] [°C] [psid] [psid] [L/m2 h]

2 L 0.1N NaOH flush 1:45 0.5 24 10 0 0.16 22 14 17 96
1 L 0.1N NaOH total recycle 1:50 0.5 24 10 0 0.16 22 14 17 96
Normalized Flux testing 2:20 0.5 24 10 0 0.16 22 14 17 96
Integrity testing 2:10 30 0.001
1 L Storage solution recycle 2:20 0.5 24 10 0 0.16 22 14 17 96

Figure 15. Example of data collection sheet for a TFF performance characterization experiment

Test the Process!

After choosing the membrane,
module, and all operating parameters,
run the entire process to ensure that
performance meets all criteria for
acceptability. During the process,
monitor flows and pressures. Collect
samples of all initial and final streams.
Calculate process time to ensure that it
is within the expected range. Test the
quality of the final product with
reliable assays, ideally the assays that
will be used during actual processing
for qualifying product release.

In order to understand where the
product is going during a process, it is
important to calculate not only yield,
but also mass balance. Determine the
total protein in each of the retentate,
the filtrate, and the unrecoverable
holdup volume. Ideally, these amounts
sum to the total amount that was put
into the unit operation. If they fall
short, there were likely some
adsorption and/or solubility losses
during the process. However, if the
amount of protein unaccounted for is a
large percent of the total, either the
process is not operating correctly or
some operating parameters need to
be changed to reduce the losses. The
yield and mass balance follow the
law of conservation of mass where:

Vo * Co = Vr * Cr + Vf * Cf + Vh* Ch

The subscripts o, r, f, and h refer to
original, retentate, filtrate, and holdup,
respectively. The percent yield in any
one of the streams can be calculated
by dividing the amount protein in that
stream by the total amount in the
feedstock. For instance, the yield in
the retentate is calculated as:

Yield [%] = 100* Vr * Cr / Vo* Co

Finally, to understand how robust a
process is to feedstock variability and
multiple cycles, it is very helpful to run
the process several times. Although
this is not always possible, especially
when feedstock is extremely limited, it
can help guard against unexpected
performance degradation once the

Labscale. Benchtop TFF System with
Pellicon XL module. Complete, linear
scalable solution for small-volume
processing.

process is in place. In addition, it will
help to ensure that the process
parameters were not determined
based on a best-case run that is not
reproducible.

Putting the Process Together

Once a protein processing procedure
has been developed, it must be
integrated into a complete process.
The typical sequence of steps in an
ultrafiltration/diafiltration process are
outlined in figure 16.

Set Up and Pre-Use Cleaning