Chromatography Forum

Hi everyone.

Hope I don't start an argument, as I'm think there may be two camps on the issue, but:

When performing the carry over tests for PV / OQ that Agilent specify Caffeine and a blank. Would you have a needle wash on in the method?

My initial thought is no as the injector purges before injection and surely you're looking for the amount of carryover from the previous vial. The NW which isn't used in all our methods would, to me, risk giving a false pass as your cleaning the needle. But the validation SOP is less than clear, no needle wash specified but use isn't ruled out.

Thoughts appreciated (or even better someone looking at the ALS settings in the method, we don't for whatever reason have there manufacturer methods on the system). Or a link to pass to QA

Thanks

J

I perform the carryover test on Agilent 1100 systems at least once a week. I never use the needle wash, and carryover is consistently less than 0.1% unless there's a problem with the autosampler that needs attention. Non-wellplate style Agilent autosamplers don't have a built-in needle wash, and I believe the wellplate style only includes it to reduce carryover from the outside of the needle when sampling from plates without septa. I've even seen the needle wash cause carryover problems that are absent without it, when the flush port has gotten contaminated with a "sticky" compound.

No, you do not need a needle wash. Like mentioned, the carryover comes from inside of the needle, not outside, and the needle is flushed when the injection valve is in mainpass (I.E. when your method is running). If the system is in good working order you should be able to get this to pass without the needle wash with little to no problems.