Technical data

66 Agilent 1290 Infinity LC System Manual and Quick Reference

3 Optimization of the Agilent 1290 Infinity LC System

How to Achieve Lowest Carry Over

Carryover is measured when residual peaks from a previous active-containing

injection appear in a subsequent blank solvent injection. There will be carry

over between active injections which may lead to erroneous results. The level

of carryover is reported as the area of the peak in the blank solution expressed

as a percentage of the area in the previous active injection. The Agilent 1290

Infinity autosampler is optimized for lowest carryover by careful design of the

flow path and use of materials in which sample adsorption is minimized. A

carryover figure of 0.002 % should be achievable even when a triple

quadrupole mass spectrometer is the detector. Operating settings of the

autosampler allow the user to set appropriate parameters to minimize

carryover in any application involving compounds liable to stick in the system.

The following functions of the autosampler can be used to minimize carryover:

• Internal needle wash

• External needle wash

• Needle seat backflush

• Injection valve cleaning

The flow path, including the inside of the needle, is continuously flushed in

normal operation, providing good elimination of carryover for most situations.

Automated delay volume reduction (ADVR) will reduce the delay volume but

will also reduce the flushing of the autosampler and should not be used with

analytes where carryover might be a problem.

The outside of the needle can be washed using a wash vial in a specific

location or the needle can be washed using the flush port. If a wash vial in a

tray location specified by the user is chosen then this vial should have no

septum and should contain a solvent suitable for washing the sample from the

needle. The septum is not used to avoid wiping contamination off the needle

on the downstream only to re-apply it on the upstroke. The needle can be

dipped into the vial multiple times. This will be effective in removing a small

degree of carryover but for more effective washing of the outside of the needle

use the flushport.