does the high pH of milli Q water will affect my ligation? - (Jun/07/2007 )

Hi all, In our lab our milli Q water showing a pH of 7.9 and we informed the technician. But problem is it will take some time to settle and I cant wait with my cloning. So please tell me this high pH will affect my ligation? if so can I adjust the pH and use the water??????

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I think your ligation buffer contains some buffering agents (e.g. Tris pH7,4). I think that the buffering effect of e.g. Tris is stronger than that of your water. But isn´t it possible to try it out?
Do you kow the ingredients of your ligation buffer?

P.S.: Some kits (PCR...) contain H2O aliqouts, you could also use this!? Because you don´t need much.

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Very useful suggestion, thank you

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Your measurement of milliQ water pH is probably wrong. it is extremely difficult to measure, since very very small amounts of almost any contaminant shifts it by large amounts. The buffer in the ligation buffer will certainly shift the pH to where it should be (which is probably not that far from 7.9 anyway).

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Having milliQ exposed to air will cause CO2 to "dissolve" in it in the form of carbonate ions, causing the pH to shift (as there are hardly any other ions in the water to buffer them). As the amount of carbonate is extremely small, any buffer in your ligation reaction will easily buffer that amount of carbonate ions.

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Yes you are right. I collected this information later on...thank you

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Thank you vairus......

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If anything, the pH of MilliQ should be slightly acidic, because of the carbonate ions. However, that is purely academic because the buffer you use will mop up any free H+ ions.

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I heat my in the microwave breifly, CO2 is not souble in warm water.

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