Solid Phase Extraction trap.
The trap column enables the rapid injection of relatively large sample volume into a nanoflow column.
The injection flow rate depends on the dimensions of the
trap. However, the ID of the trapping column should be in balance with the column ID.
Use of -relatively- large ID traps results in unwanted band broadening in the
final separation. The cause is the low linear velocity [column flow x
(ID
column/ ID
trap)
2] of the mobile phase
through the trap when switched in line with the column. According to the Van
Deemter equation (Van Deemter, et. al., Chem. Eng. Sci.
5 (1956) 271),
low mobile phase velocities result in a severe
decrease in separation efficiency of the trap and hence, analytes
will arrive in broader bands onto the analytical column.
300umID trap
50 umID column
100umID trap
50 umID column
delay 16 min

Trap ID |
Column ID |
Lin. velocity in |
Lin. Velocity in |
(um) |
(um) |
column (cm/min) |
trap (cm/min) |
300 |
100 |
6 |
0.670 |
300 |
75 |
6 |
0.375 |
100 |
75 |
6 |
4 |
100 |
50 |
6 |
1.5 |
Recommended trap ID/ column ID combinations
Column ID |
Trap ID |
trap flow rate (uL) |
(um) |
(um) |
at 125 bar |
200 |
200 |
40 |
100 |
100 |
10 |
75 |
100 |
10 |
50 |
100 |
10 |
25 |
50 |
3 |