[Patrick F.H. Lai]

Dear Kit-free Jim,

I have to say that I have similar experience with the QIAEX II kit.
My solutions include: (1) share the kit with neighbouring lab groups 
(2) work harder (3) do bigger experiments....
to consume the kit quicker.

Solution (2) sucks.


Pat.Lai


---- Begin Original Message ----
Hello again,

Back in the days when DNA binding spin columns and "glassmilk" were
first gaining popularity, I had the distinct and clear experience of th=
e
loss of DNA binding activity of the proprietary resin of the Bio 101
"GeneClean" kit after about a year in the refrigerator.

Now come 1998, and letting down my guard, I began to heavily rely on th=
e
Quiagen Quiaquick column to remove primers following PCR. This worked
flawlessly for about 8 months, when suddenly I begin to experience
random sample loss or greatly (0.1X) reduced recovery in about half of
cases.
(If I had used my columns at a greater rate, as one might in a larger
lab, I would not be aware of the potential problem.)

A guy across the hall had recently related to me that his Quiaquick Gel=

Extraction had "gone off" after a similar interval after purchasing two=

large boxes of columns. Quaigen apparently would not relate any
knowledge of the phenomenon. He then returned to the non-proprietary
Qian and Wilkinson (91) direct freeze-elution which has been working
well for me since the demise of "glassmilk".

It seems I need to relearn the concept of the variability of
glass-binding DNA purification techniques every few years. I believe th=
e
basis of DNA interaction with glass in the presence of chaotropic agent=
s
is still undescribed (please correct me here). Any insight into the
manufacture or treatment necessary would be helpful.

Anyone else find that their propreitary DNA binding matrix has lost
activity in a subset of cases after about 8 months? Please E-mail me
copies of any replies (drop the _no spammmmm of course).

(By the way, proteinase K, phenol, and ammonium-acetate/ethanol ppct. i=
n
combination with Quiaquick may greatly improve ligability of PCR
generated material as recently demonstrated in Biotechniques 24:
578-580.)

Thanks very much,

Jim (kit-free again) Graham PhD
Biology Department


---- End Original Message ----



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