is there a criteria for carryover peaks?

[flora0975]

I am runing a method development, the carryover can not be removed. The linearity, accuracy and precision are pass the specifications. How do I need to address the carryover in the method validation?

Is there any inforamtion from FDA or USP mentioned a carryover reporting threshold?

Thanks.

[tom jupille]

Any system will have *some* carryover (ypically it will be down around 0.01% or so). Measuring it is usually addressed in PQ of the system rather than the method, with a typical limit of 0.1% max.

[remesquaddie]

Do you have a "needle wash " installed ?
Tony Vella
www.hplcworks.net

I am runing a method development, the carryover can not be removed. The linearity, accuracy and precision are pass the specifications. How do I need to address the carryover in the method validation?

Is there any inforamtion from FDA or USP mentioned a carryover reporting threshold?

Thanks.

[flora0975]

Yes, I did try different needle wash. The carry-over still can be observed.

Do you have a "needle wash " installed ?
Tony Vella
http://www.hplcworks.net

I am runing a method development, the carryover can not be removed. The linearity, accuracy and precision are pass the specifications. How do I need to address the carryover in the method validation?

Is there any inforamtion from FDA or USP mentioned a carryover reporting threshold?

Thanks.

[Juan2011]

I did experienced this problem when I was trying to assay two drugs simultanously. The sample cocentration was 1000ppm and 700ppm repectively. I had problems specially for the compound with 1000ppm. I finally dilute the sample and insert one blank in between(not prefered but no option). It did help that time. That might be due to overloading. Try it , hope it help.

[remesquaddie]

Is the " needle wash " solvent composition such that it will dissolve the sample OFF the needle?

Do you have a "needle wash " installed ?
Tony Vella
http://www.hplcworks.net

I am runing a method development, the carryover can not be removed. The linearity, accuracy and precision are pass the specifications. How do I need to address the carryover in the method validation?

Is there any inforamtion from FDA or USP mentioned a carryover reporting threshold?

Thanks.

[flora0975]

I am using sample diluent (same to sample prep) as needle wash, it helps but still can not totally remove the carry-over.

Is the " needle wash " solvent composition such that it will dissolve the sample OFF the needle?

Do you have a "needle wash " installed ?
Tony Vella
http://www.hplcworks.net

I am runing a method development, the carryover can not be removed. The linearity, accuracy and precision are pass the specifications. How do I need to address the carryover in the method validation?

Is there any inforamtion from FDA or USP mentioned a carryover reporting threshold?

Thanks.

[tom jupille]

How much carryover are you actually seeing?

[Rob Burgess]

It might help if you let us know what HPLC system you are using - they do not always deliver they "same" performance of carryover. For instance I have had issues with needle seat and rotor seal contamination and know amount of "needle" wash would solve this issue.

Also you have to question what vendors actually do on IQ/PQ - they tend to choose something polar (like caffeine) that they know will wash off. On intstall it might make more sense to choose your most problematic compound as a measure of "fit for purpose" qualification!

[remesquaddie]

How about doing something new?
Assign a vial with the needle wash solvent in it, then have the autosampler pick up a small amount from that with a short [1min] run time, then to the real sample and run that?
Do that every time before making a real sample injection.
This is rather old stuff but might work for you.
Good luck

I am runing a method development, the carryover can not be removed. The linearity, accuracy and precision are pass the specifications. How do I need to address the carryover in the method validation?

Is there any inforamtion from FDA or USP mentioned a carryover reporting threshold?

Thanks.

[sepscientologist]

And what is the analyte? If it is pretty hydrophobic then going to a pure acetonitrile wash will probably eliminate your carryover.

[tom jupille]

We are sort of drifting off the original question. So long as the carryover is sufficiently small to not significantly affect the quantitation, we can ignore it.

Also, we have to remember that there are two types of carryover:
- physical (residual sample trapped in unswept parts of the system)
- chemical (sample components adsorbed on some surface in the system)

*All* systems have *some* physical carryover. So long as it is down around the 0.01 - 0.05% level, we can usually live with it by arranging things so that our high-level standards or samples are run at the end of the sequence. In a worst-case scenario, running a "dummy" blank between injections should eliminate the problem because the response on successive blanks is that of exponential decay (assuming 1% carryover, the first blank would have 1%, the second blank would have 0.01%, the third would have 0.0001%, and so on). This type of carryover is approximately unaffected by the chemistry of the needle rinse solution (so long as the analytes are soluble in it!)

Chemical carryover is much less common. In general, if you run a high-level standard and then a series of blanks, the decay will be much slower than exponential, and different compounds will decay differently. If that's the pattern that flora0975 is seeing, then yes, the needle rinse is a strong suspect, but adsorption inside the system must be considered as well.