Problems Assaying Caffeine by USP

[Murph]

we are following the USP method for caffeine assay and get awful reproducibility. Not to mention always OOS (low). The mfg. says none of their other customers have this problem. Anyone else encounter issues? should be very straight forward.

[KM-USA]

An issue with a USP procedure?


How shocking!

I won't even ask if you're assaying coffee, tea, food, or pharmaceutical, your issues sound way more basic than that.

[tom jupille]

a *lot* more information is needed.
- instrument/column details?
- do other methods work OK on this system?
- matrix?

[Murph]

using a PE Series 200. no issues with other methods. We're following the USP method to the letter. I hate USP methods!

[Murph]

An issue with a USP procedure?


How shocking!

I won't even ask if you're assaying coffee, tea, food, or pharmaceutical, your issues sound way more basic than that.

We're assaying caffeine raw material.

[Blazer]

How low for OOS values? Wildly OOS or just barely? You also say awful reproducibility. What does this mean? Do you mean for your caffeine standards? Your intersample results?

I do see in the USP Monograph that there is a note for the standard and sample preparation to shake and sonicate, if necessary. Perhaps your low results are due to incompletely dissolved material?