Bio-Rad BioLogic Sample Loading Loops - Manual (Page 6)

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Load phase With the AVR7-3 injection valve in the LOAD position, sample is injected
into the sample chamber end of the DynaLoop via port 3 on the injection
valve using a peristaltic pump or a syringe. As the DynaLoop fills with sample,
the sliding seal moves toward the buffer end assembly. The sliding seal
O-ring and closed check valve within the sliding seal assembly prevent
mixing of buffer and sample (Figure 2).
Fig. 2. Sliding seal assembly. (Check valve is closed.)
Injection phase With the AVR7-3 injection valve in the INJECT position, buffer delivered from
the BioLogic gradient pump pushes against the sliding seal assembly, and
delivers sample to the column. No buffer passes through the seal assembly
into the sample chamber while the seal assembly is moving.
Flush phase When the sliding seal assembly contacts the sample end cap, the check
valve opens and buffer passes through the sliding seal. Sample is com-
pletely flushed from the DynaLoop (Figure 3) onto the column in a concen-
trated band. When the sample is loaded onto the column and sufficient
buffer has flushed all sample from the loop and check valve, the AVR7-3
injection valve will automatically switch to LOAD after the programmed
sample load volume is injected. The gradient pump is now
connected directly to the column, facilitating accurate gradient elutions.
Check valve
(closed)
Sample end
connector
Sliding seal assembly
separates buffer from
sample
O-ring seals
BUFFER SAMPLE