# Reference Mix for 6545 QToF

Hi, I have just noticed that the reference mix states that it should be kept at room temperature, but we keep it in the refrigerator. (All the components, and the mix when made)

Will this cause any precipitation or stability issues?

I haven't really noticed anything that I can tie to that, but I have been having some issues with the baseline so I am curious.

Thanks for any help.

Parents
• Ok, we found the number G1969-85001 ( API-TOF Reference Mass Solution Kit).

This mix contains 2.5 mM Hexakis(1H, 1H, 3H-tetrafluoropropoxy)phosphazine, 5.0 mM Purine and 100.0 mM Ammonium Trifluoroacetate. The first two are in ACN/water 90:10, the last in 100% ACN. That means your mix (or two of the single standards) contains some percentages of water, dissolved in acetonitrile.

Depending on the temperature of your freezer, it is possible that water crystallizes out of that mix and with it some components. If you warm it up to ambient and shake it before use, there is no problem with getting smaller signals.

Norbert

• Ok, we found the number G1969-85001 ( API-TOF Reference Mass Solution Kit).

This mix contains 2.5 mM Hexakis(1H, 1H, 3H-tetrafluoropropoxy)phosphazine, 5.0 mM Purine and 100.0 mM Ammonium Trifluoroacetate. The first two are in ACN/water 90:10, the last in 100% ACN. That means your mix (or two of the single standards) contains some percentages of water, dissolved in acetonitrile.

Depending on the temperature of your freezer, it is possible that water crystallizes out of that mix and with it some components. If you warm it up to ambient and shake it before use, there is no problem with getting smaller signals.

Norbert

Children