The video says to connect a luer needle to the output of the filter. But the filter doesn't have a threaded interface. The needle does have a threaded interface.
Thats what I do. The ID of the needle is tapered and matched the taper on the output of the filter, so it slips on and friction fits.
This. Called Luer slip.
And other random particulates. Most everything except the endotoxins. Those buggers are too small.
The gray market raw powder cannot be assumed to be sterile. Actually, even the stuff produced in pharma grade factories isn't either.
So, this final purge to get the holdback in the filter - how many of you practice it? From what I read, the holdback in a Biologix 13mm 0.22μm filter is about 15-25 μ liters (2-3 units). Is that enough to worry about? Or maybe its easy enough?
That hold back is after purging. No practice is necessary. Watch a video on it once or twice.
I disconnect filter, draw air into syringe, reconnect filter, and push some air in to purge and recover most of the hold up volume. HOWEVER, when you feel resistance, ie, the plunger feels “springy” and pushes back, STOP. If you push hard enough, you’ll overcome the filter’s “bubble point”, and some foam will come out. Peptides are most often damaged at the air/water interface, and foam, made up of millions of tiny bubbles, is essentially the most air/water interface area that can possibly be created, so you don’t want that in your vial. It’s only a tiny amount of loss anyway, so don’t worry about.
hmmm - the source I got that from says it's before the purge. Maybe it's not right. I can look more.
My personal experience is that the holdback in a 13 mm filter before air purging is significantly more than 2 to 3 units. I suppose we needed to specify filter size.
I stated "Biologix 13mm 0.22μm filter". I'll look around a bit more. In any case, I guess purging seems to be easy enough. No point in leaving behind anything that can be recovered with an easy purge.
I guess it varies a lot between brands.
I verified that you are, in fact, correct. That holdback is post-purge. Pre-purge it can be 250-300 μL (25-30 units). Glad I asked.
It’s a good question and something I thought was necessary, but no. That just increases dilution of your peptide. No prewetting.
Well, you can always compensate by adding less bac later. But I'd rather avoid it if it's not useful.
Pall themselves rates hold back as <3 units AFTER air purging, assuming we are talking about the acrodisc line or similar.
The primary purpose of pre wetting when it’s done in labs, from what I understand, is to ensure you flush contaminants from the filter. However, when using modern, quality PES filters, which is part of the standard process of preparing samples for chromatographic analysis, these days any filter that would impart particulates would be considered unacceptable. “Non-shedding” is the industry standard for sterile PES filters. These are also used by compounding pharmacies to sterilize medications, so you could see hour introducing contaminants would be a problem there too.
and to your point. Reputable GB's are great as part of many of the buys are the tests u mentioned. I always feel more confident w GB product vs vendor XYZ in China.
Don’t waste your money. Just buy filters, syringes and cheap needles from Amazon. You don’t need to inject yourself with them. Get Biologix filters though. $50 for 100 direct from Biologix. Free shipping.
