Chromatography Forum

Dear all,
I work in GMP Quality Control lab. I use Milli-Q water for HPLC an other kind of analysis.
Can you suggest me the best way to managment this water (storage for few days, use only fresh water...???) to obtain the best results, both for regulatory and analytical point of view.
Thanks

In the GMP labs were I have worked, the storage period for water of the type like you use has been stated in an SOP. Depending on the SOP and/or the company, this period was either 1 day or 2 days.

A rule of thumb in GMP labs is that the solution or solvent can be used for 1 day unless there is an SOP that provides another storage time.

So, if you don't have an SOP that gives a stated storage time for your water, then I would go with 1 day storage for analytical use.

Regards,
Dan

For HPLC water from the laboratory purification system - freshly prepared water in suitable vessels (the vessel type should be defined and described in the SOP) - should be used at the same day, i.e. at the end of the day to waste the residual amounts.

HPLC water from commercial supplier - Not more than 24 hours from the opening.

Unless fresh HPLC water is technically necessary for your assay (in other words, you've demonstrated that using "older" water delivers equivalent, acceptable results), I can't see why "fresh" water would be necessary. Trying to figure out how many hours and minutes water is around before being used seems like too picky even to FDA. If I assay 30 samples overnight, my water for the later assays is "older" than for the first. Do you add acetonitrile from one bottle into a half-full reservoir containing "old" acetonitrile, etc.?

Dear all,
thank you very much for all your reply.
dear Consumer Product G. I agree with your observation but water is a quite different from acetonitrile; one problem is bacterial contamination. If I use water with a high bacterials counts (> 1000 cfu/ml for example) can I have some problems with DAD at low wavelenght (near 220 nm) ?

bye

GT

Not only with the detector, but with the filters, frits,lines etc.

Again, one should ask oneself: Should the analytical be work done to satisfy regulations or to get as close to a true answer as humanly possible?
I test (UV, and/or fluorescence as needed) any new run, sometimes every bottle, of MilliQ water used for HPLC in this lab. This has been mentioned before. If your bottles are clean, etc., microbes do not have a chance. I have had bottles for at least one year in the cold room which tested pefectly OK. Water at room temperature for several months, with several portions removed (quickly, to reduce catching dust...), has been better (UV) than freshly opened commercial HPLC water. Though it is not easy to test liquids for HPLC worthiness, I don´t like to work "blind", and especially don´t want to relegate responsibility to regulators.
(I use an emptied prep. column with a needle valve attached to one outlet, ~100mL vol., fill it with the testing liquid, evakuate 10+ min. then pressure it with N2, run it through the detectors. Incidentally, as mentioned earlier, you will be surprised how much real "dirt" can be "coverd" by gases, even He, if you don´t degas carefully).