RSD variation in HPLC system

[shoaibmashori]

Dear All,
Iam using 2695 hplc systems, iam getting RSD up to 8-10%, my system's pressure is stable, no air bubble in injector needle, can any one letme know the possible causes?
Regards
Shoaib

[Consumer Products Guy]

RSD variation in area counts, or in retention times????

If retention times are stable/consistent, sounds like injection issue.

[spazmo]

If there are no obvious signs of air bubbles or leaks in the autosampler the first place I would look is the six port valve, the rotor may be baddly worn or damaged.

[mattmullaney]

If your samples are fairly viscous, or if sample viscosity varies a bit over different methods, check the sample draw speed on the plunger. Are you doing partial-loop injections or full-loop, and if you're using partial-loop injections are you ensuring that the injection volume is less than one-half of the loop volume?

[scottythree]

Also verify your needle wash functionality.

[LCbob]

Hi

If you have checked all the above solutions, then it may be the seal pack and / or one of the valves ( V2 ). If you feel comfortable remove the right hand cover and take a look to see if anything has been leaking. The manual helps with overhaul of these parts.

Good Luck