Precision of 2~3 uL injection on 2695e
Hi, since there is no section for 2695, I have to post it here.
I have some problem with the precision of sub-5 uL injection on 2695. Two methods I received were developed/validated on Agilent 1100/1200, but injection precision on 2695 is challenging even with 25-uL syringe installed and configured in system:
==Method 1===
Sample diluent: 75% Ethanol/25% Water
Injection volume: 3 uL, slow speed draw
MP A: water/TFA
MP B: ACN/TFA
Gradient: 25 min, 90% A to 10%A
Column: 4.6x150 C18
Flow: 1 mL/min
Wavelength: 228
%RSD (n=6): 3.3, need < 2.0
Bracketing recovery: 95 to 105, randomly up and down
Carryover: no
==Method 2===
Sample diluent: 30% ACN/70% Water
Injection volume: 2 uL
MP A: water/H3PO4/TEA
MP B: ACN
Gradient: 3.1 min, 90% A to 10%A
Column: 4.6x50 C18
Flow: 1.5 mL/min
Carryover: no
%RSD (n=6): 5.6, need < 2.0
Bracketing recovery: randomly up and down
Carryover: no
LCs are serviced routinely by Waters engineer.
Does any one know how to improve low-volume injection precision on 2695?
I have some problem with the precision of sub-5 uL injection on 2695. Two methods I received were developed/validated on Agilent 1100/1200, but injection precision on 2695 is challenging even with 25-uL syringe installed and configured in system:
==Method 1===
Sample diluent: 75% Ethanol/25% Water
Injection volume: 3 uL, slow speed draw
MP A: water/TFA
MP B: ACN/TFA
Gradient: 25 min, 90% A to 10%A
Column: 4.6x150 C18
Flow: 1 mL/min
Wavelength: 228
%RSD (n=6): 3.3, need < 2.0
Bracketing recovery: 95 to 105, randomly up and down
Carryover: no
==Method 2===
Sample diluent: 30% ACN/70% Water
Injection volume: 2 uL
MP A: water/H3PO4/TEA
MP B: ACN
Gradient: 3.1 min, 90% A to 10%A
Column: 4.6x50 C18
Flow: 1.5 mL/min
Carryover: no
%RSD (n=6): 5.6, need < 2.0
Bracketing recovery: randomly up and down
Carryover: no
LCs are serviced routinely by Waters engineer.
Does any one know how to improve low-volume injection precision on 2695?
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Answers
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Hi ronery,
It sounds like you have already made all the hardware changes to give you the best result for low volume injections, so now it is just a matter of ensuring that the rest of the hardware is not adding error to your analysis. Can I ask what volume you are trying to inject and what RSD you are getting today?
Marc
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