desinr-gal said:
Chili777 said:
desinr-gal said:
cookieguggleman said:
Ugh, could use some help—I'm reconstituting an ARA 290 vial and pushing it through a filter into a pen cartridge. I'm nearly finished, but when I try to get it through the filter into the cartridge, it WILL NOT BUDGE. Also gave a really low gauge luer needle a shot. Any ideas why this is happening or how to deal with it? Filtering it is something I'd REALLY like to do (I forgot to wipe the vial top with an alcohol wipe
)
Has this happened to anyone else? Could it be this particular peptide?
I run into this all the time using the Tisch 4mm filters. Swap in a fresh filter. . Certain ones just seem stubborn. I prime mine with bac water beforehand, and that tends to make it easier, though it doesn't work every time.
Which brands have worked best for you, and which ones are actually good quality? I've been considering giving them a try, but I came across reports that certain brands clog very often. Some reportedly clog as much as 25% of the time. I also checked out premium options, for example Fischer Scientific, and the price can reach $10 apiece.
The only ones I've bought are Tisch, since that's what the vendors I mainly order from carry. Amazon has some brands, but I've only come across 13mm and larger, and that size causes more pep loss than I'm comfortable with..
I stay away from Amazon since I share a Prime account with relatives and I'd rather not get into explaining my peptide supplies to them..lol
I'd really like to know more about which brands exist and how often they clog—could you share a link?
thanks.
I ran this by Gemini, and according to it, going with 4 mm is the right call for peptides:
Peptide Loss in Syringe Filters
For peptide work, both the membrane material and the filter's dimensions have a major influence on how much peptide is lost. With biological samples, polyethersulfone (PES) and polyvinylidene fluoride (PVDF) are the usual picks because they bind proteins weakly, which cuts down on peptide adsorption and loss during filtration. PES in particular is suggested for aqueous solutions and tends to preserve peptide integrity well.
Volumetric loss is tied directly to filter size. Per studies, a 4 mm syringe filter loses far less volume—roughly 5–7 units—whereas a 13 mm filter loses around 29 units when a reconstituted peptide solution is filtered. For volumes up to 4 mL, 4 mm is the best choice to keep loss low, while 13 mm suits larger volumes. Going bigger still (e.g., 25 mm and 33 mm) means even more peptide loss, since holdup volume grows.
As for peptide concentration, filtration barely changes it. Research shows post-filtration concentration shifts are too small to matter in practice, and occasionally concentration even rose slightly—likely because the filter holds back water while peptides pass through. The loss, then, is mostly volumetric rather than from peptide degradation or binding.
Brand and filter quality count too. Certain generic filters can have larger holdup volumes than trusted brands such as Tisch, which are recognized for consistent performance. For the best recovery, particularly in low-level peptide analysis, high-quality filters like Agilent Captiva Premium PES syringe filters have shown superior recovery rates (>97%) along with lower column backpressure.
Bottom line: to keep peptide loss down, choose a 4 mm PES syringe filter for volumes up to 4 mL, make sure it is sterile and low-protein binding, and stick with reputable brands to avoid holdup volume variability.
Edit: Grammer
