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 (IDcolumn/ IDtrap)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.
| 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 |