Questions about the choice of the syringe filter

[vanadium]

Hi, I sometime prepare steroid solution (10 ml vials) but I have a problem concerning the syringe filter.

I presently use whatman .45 um (diameter 25 mm) PVDF syringe filter but there are too slow in my opinion and PVDF membrane are know to not be really fast.

I would like to use .22 um to have a sterile filtrate, so because of the slow PVDF filters I tried the Nylon and PES. I read on a forum that Nylon are perfect for steroid solution and much faster than PVDF but Nylon is an Hydrophobic membrane and I don't understand why they use Nylon for non-polar liquid. So I bought .22 um 25mm diameter Nylon filter (from ebay, not whatman) and tested it... Results : impossible to filter ! 10x slower than .45 PVDF filter.

As I've also bought PES filter from the same seller I could filter a sample with this one. Results : a little better than nylon but still very sloooow

My questions are :

1) Is it necessairy to have a .22 um to have a sterile solution or the .45 gives acceptable results concerning the dangers of bacteria ? I would point out that I heat the solution at 100°C before for most type of steroid.

2) Which membrane are the best for a steroid based solution ? PVDF, Nylon, PES? Whant about PTFE and other membranes such as glass fiber ?

3) Why my filtration is soooo slow ? Because of the .22 um instead of .45 um ? or the use of other type of membrane ? or the non-whatman filter are poor quality ?

4) Did you experience many differences between whatman filter and other cheaper filters ?

5) what is the quickest membrane ?

6) What about the quality of filtration of the vacuum filtration all in one unity. I used PES membrane. At first it was good, but I let it overnight with vacuum and the next day I could see some part of the membrane has been dissolved in the solution . I threw all the product. Poor quality. Maybe you know better membrane for sterile unity because it needs less work.

Thanks in advance for your answers,

Have a nice day

Vanadium

 

[Buttman3]

Hi, I sometime prepare steroid solution (10 ml vials) but I have a problem concerning the syringe filter.

I presently use whatman .45 um (diameter 25 mm) PVDF syringe filter but there are too slow in my opinion and PVDF membrane are know to not be really fast.

I would like to use .22 um to have a sterile filtrate, so because of the slow PVDF filters I tried the Nylon and PES. I read on a forum that Nylon are perfect for steroid solution and much faster than PVDF but Nylon is an Hydrophobic membrane and I don't understand why they use Nylon for non-polar liquid. So I bought .22 um 25mm diameter Nylon filter (from ebay, not whatman) and tested it... Results : impossible to filter ! 10x slower than .45 PVDF filter.

As I've also bought PES filter from the same seller I could filter a sample with this one. Results : a little better than nylon but still very sloooow

My questions are :

1) Is it necessairy to have a .22 um to have a sterile solution or the .45 gives acceptable results concerning the dangers of bacteria ? I would point out that I heat the solution at 100°C before for most type of steroid.

2) Which membrane are the best for a steroid based solution ? PVDF, Nylon, PES? Whant about PTFE and other membranes such as glass fiber ?

3) Why my filtration is soooo slow ? Because of the .22 um instead of .45 um ? or the use of other type of membrane ? or the non-whatman filter are poor quality ?

4) Did you experience many differences between whatman filter and other cheaper filters ?

5) what is the quickest membrane ?

6) What about the quality of filtration of the vacuum filtration all in one unity. I used PES membrane. At first it was good, but I let it overnight with vacuum and the next day I could see some part of the membrane has been dissolved in the solution . I threw all the product. Poor quality. Maybe you know better membrane for sterile unity because it needs less work.

Thanks in advance for your answers,

Have a nice day

Vanadium

I don't know the answers to all of your question, but what I can say is that you can make it easier to filter using a 0.2 filter by doing the following:

* warm your oil before filtering. It will go through the filter quicker.
* get a large syringe (20ml or bigger), so it doesn't hurt your thumbs when you use it
* get a caulking gun and set up your unit to look something like this

Good luck, cheers.

 

[JeffA]

Is that the 47mm filter holder? Planning on making the move from the syringe filters to a membrane one like that. Like the idea of buying 100 membranes for $30 instead of $4 for a syringe filter.

 

[BEASTZ6]

I use a Whatman .20 syringe filter - PVDF. Nylon is ok too. Heat the oil, but not too hot to melt the filter. I find that it is much easier to use a 3 ml syringe than a 10 ml syringe. Less strain on your thumbs.