hello, i m using PVPP for Fragaria RNA extraction, no need to be autoclaved. i m using in it at the first step of the Quiagen RNA extraction Kit ... Just add it in to your sample powder in the same time of extraction Buffer (with Beta mercapto)

Boustani is right, there is no need to clean up the PVPP as you just use it in the first step of sample clearance. Your tissue samples aren't RNase free anyway. This is why you add BME and RNase inhibitor to your extraction buffer (e.g. in the RNeasy kits from Qiagen).

In my case, I need to use it to remove humic acid substances from nucleic acid extracted from sediment samples. They are pretty dirty even following phenol-chlor steps. So in practice everything that comes into contact with the nucleic acids should be free of potential Rnase enzymes.

Melting point of PVPP is between 150 - 180 °C (glass temperature), and it's not soluble in water ... So i imagine that you can autoclave it.

I saw on some protocols: a purification of RNA samples on PVPP colons that you can prepare yourself using empty RNAse Free colons (Ependorf) ...it can be a good idea

PS: if you didn't put your hand on the PVPP bottle (I think it RNAse Free)

GOOD LUCK

I don't think you need to worry about it. People (myself included) often go overboard making sure everything is RNase free.

If you have a pure RNA sample, you can test for RNAse activity in anything doing something similar to this:

-remove an aliquot of RNA (may want to dilute it some in water or PBS)

-add the PVP to the aliquot of RNA and leave at RT or 37deg. for a couple of hours (or overnight). Include a control with no PVP added.

-run the treated sample vs your untreated sample on a Bioanalyzer (you may need to cleanup the treated sample before this)

-if no RNase is present, curves should be similar.

Some "RNase-free" materials and chemicals did not receive special treatment for the "RNase-free" label. They were simply tested for the presence of RNase activity and certified RNase-free.

Another option is to test for the presence of active RNase during sample prep or after sample prep.

During sample prep: during the PVP treatments, incubate a couple of samples at room temperature or 37deg. for 20 minutes, then proceed with the protocol. Check RNA integrity on a Bioanalyzer to observe any degradation in the samples (if they all look the same, you probably have no RNAse in your PVP).

If you are worried about RNase in the end product, remove an aliquot of the RNA and store in the dark at room temperature overnight. Store original sample at -80deg. The next day, use a Bioanalyzer to compare the aliquot stored at room temperature against the frozen sample. The curves should be close to identical.

No need of DEPC treating PVP, because it is in powder form itself, just add to your sample in the crushing step itself, it works.