Filtering finished oils

[readalot]

We need some consideration of human nature here.

If the larger needle isn't adding any additional perceived resistance vs no needle, because its diameter is larger than the outlet of the filter, I'm not going to push harder if that needle is 1mm, 2mm or 3mm wider in diameter than the outlet, yet the velocity will decrease as flow from the filter outlet tapers up into the larger space. Unlike the significant easing of effort going from 25g to 20g, emptying the syringe much faster, I can't feel a change in effort required or time any differences in emptying the syringe with or without the 16g needle attached to the filter.

It's the narrow throat on the filter outlet that's causing the resistance I feel, regulating how hard I push, not the wider diameter needle attached to it, so pressure applied will be constant.

Yes, in the case you give that is correct. In general, just like with doing injections, always better to go slow and minimize injection jet into tissues. Hence, if you are patient no real issue drawing and injecting with 29g needle vs 23 g needle. Your point about 16 g needle is great. If someone using a smaller diameter needle than 16 g, makes sense to take it slow during peptide filtration.

 

[readalot]

We need some consideration of human nature here.

so pressure applied will be constant.

Amen. So in short, try to push slower than last time, lol.

 

[LGOP528]

It's just a rearrangement of Hagen-Poseuille flow (fully developed, laminar flow, Newtonian viscosity, etc) pressure drop equation giving injection force.

https://www.sciencedirect.com/science/article/abs/pii/S0378517318308305

Nice paper.

I will read it, I have a few things I have to do so I will need a little time. It does look like the assumption of laminar flow was made.

 

[readalot]

Is it solely the contact with the metal that is the problem or other proteins? If it is solely the metal, I would think the boundary layer is the issue, if it is other proteins, I would think turbulence would be the main concern.

Yes great point. At some point just the diameter reduction will fundamentally change the flow regime. Hence in laminar flow maximum shear stress is at the wall. In turbulent flow, not so simple. We can speak of averages and using LES models, but in general better to keep flow laminar and minimize wall shear stress. And this of course doesn't bring into play as the interfacial effects (air/liquid interface), etc.

 

[readalot]

I will read it, I have a few things I have to do so I will need a little time. It does look like the assumption of laminar flow was made.

No rush Brother. Yes this is laminar flow treatment. Good constituitive model for stuff we inject. I'm not getting into turbulence models today haha.

 

[LGOP528]

So the equation you posted is the force needed for an injection. I wish these papers were made available to the public. We are missing a lot of information on that one. I did search for another paper that was referenced in your paper and this might be more complicated.

Injection forces of concentrated protein therapeutics are influenced by syringe properties (e.g., needle diameter) and injection speed, and are driven by solution properties such as rheology. In the present study, it is demonstrated that concentrated protein therapeutics may show significantly reduced injection forces because of shear-thinning (non-Newtonian) behavior.

https://www.sciencedirect.com/science/article/abs/pii/S0939641114000411

If this is a non-Newtonian fluid it makes this more complicated and not being able to read the whole paper makes it worse.

 

[readalot]

So the equation you posted is the force needed for an injection. I wish these papers were made available to the public. We are missing a lot of information on that one. I did search for another paper that was referenced in your paper and this might be more complicated.

Injection forces of concentrated protein therapeutics are influenced by syringe properties (e.g., needle diameter) and injection speed, and are driven by solution properties such as rheology. In the present study, it is demonstrated that concentrated protein therapeutics may show significantly reduced injection forces because of shear-thinning (non-Newtonian) behavior.

https://www.sciencedirect.com/science/article/abs/pii/S0939641114000411

If this is a non-Newtonian fluid it makes this more complicated and not being able to read the whole paper makes it worse.

There's no derivation in the paper. You can derive it from standard HP equation.

Hagen–Poiseuille equation - Wikipedia

en.m.wikipedia.org

Change delP to expulsion force by multiplying RHS of equation by cross sectional area of syringe. Then you get RHS in terms of syringe ID and needle ID.

Depending on your personal ethics and opinion of publisher paywalls there is Scihub.

 

[LGOP528]

There's no derivation in the paper. You can derive it from standard HP equation.

Hagen–Poiseuille equation - Wikipedia

en.m.wikipedia.org

Change delP to expulsion force by multiplying RHS of equation by cross sectional area of syringe. Then you get RHS in terms of syringe ID and needle ID.

Depending on your personal ethics and opinion of publisher paywalls there is Scihub.

It isn’t about the derivation. It isn’t calculating the shear stress. It is the force to push the plunger but even then the viscosity can change due to shear thinning. This is a non-Newtonian behavior. Everything we have talked about so far, has been under the assumption that we were dealing with a Newtonian fluid. Now the paper I posted said therapeutic proteins but seeing as how the difference between peptides and proteins is the length of the amino acid chains, I don’t think it is safe to make that assumption anymore.

To put it another way, if I was working on this problem for work, my next step would be to verify if that assumption is valid or not with the specific fluid I was dealing with.

 

[readalot]

It isn’t about the derivation. It isn’t calculating the shear stress. It is the force to push the plunger but even then the viscosity can change due to shear thinning. This is a non-Newtonian behavior. Everything we have talked about so far, has been under the assumption that we were dealing with a Newtonian fluid. Now the paper I posted said therapeutic proteins but seeing as how the difference between peptides and proteins is the length of the amino acid chains, I don’t think it is safe to make that assumption anymore.

To put it another way, if I was working on this problem for work, my next step would be to verify if that assumption is valid or not with the specific fluid I was dealing with.

Correct. Newtonian flow. Originally I posted this equation for oil injections and yes one needs to verify the fluid behavior they are working with.

For the peptide concentrations we are working with, next step would be to see if Newtonian fluid assumption holds for dilute concentrations. Don't have the plots in front of me but pretty sure that would be fine assumption for these dilute concentrations we are working with by reconstituting peptides.

 

[MissedArmDay66]

All this caulking gun talk makes me wonder if someone makes a small gun that is a reasonable size for holding a syringe or if you guys are just using a regular caulking gun lol

 

[Ateam2023]

All this caulking gun talk makes me wonder if someone makes a small gun that is a reasonable size for holding a syringe or if you guys are just using a regular caulking gun lol

this is my very cheap "very effective " caulking gun ,

 

[MissedArmDay66]

this is my very cheap "very effective " caulking gun ,

But it’s basically the same size you would use to apply rtv or regular caulking? - disregard, the picture just expanded to where i can see the syringe

 

[Sampei]

All this caulking gun talk makes me wonder if someone makes a small gun that is a reasonable size for holding a syringe or if you guys are just using a regular caulking gun lol

It's a real caulking gun buddy xD

 

[Photon]

I just went through a super long thread about multi dose vial adapters...and realized that all the good adapters are in EU and none in US.

It also seems like these filtered spikes don't seem to do well with high BB compounds? The blunt filtered needles are also 16/18G which will probably destroy my vials in no time..blunt needles are really bad for coring..

I've seen some anti-coring non-filtered 25g needles, is that preferred for drawing high BB stuff or is there something else recommended for US? I was hoping to use some 50ml vials but looks like the stopper wont last that long.

 

[Ghoul]

I just went through a super long thread about multi dose vial adapters...and realized that all the good adapters are in EU and none in US.

It also seems like these filtered spikes don't seem to do well with high BB compounds? The blunt filtered needles are also 16/18G which will probably destroy my vials in no time..blunt needles are really bad for coring..

I've seen some anti-coring non-filtered 25g needles, is that preferred for drawing high BB stuff or is there something else recommended for US? I was hoping to use some 50ml vials but looks like the stopper wont last that long.

For high BB compounds get spikes without filters. Attach spike and draw from "contaminated" vial into large syringe, insert spike into "Ultra spec" particle free vial, attach .22um 33mm PTFE syringe filter, inject into vial.

Then you've got filtered gear in a particle free sterile vial, and from then on can draw into the syringe without creating coring particles, and as a bonus, pull much faster than drawing via a needle.

 

[Photon]

For high BB compounds get spikes without filters. Attach spike and draw from "contaminated" vial into large syringe, insert spike into "Ultra spec" particle free vial, attach .22um 33mm PTFE syringe filter, inject into vial.

Then you've got filtered gear in a particle free sterile vial, and from then on can draw into the syringe without creating coring particles, and as a bonus, pull much faster than drawing via a needle.

And if the vial is already filtered?
Draw using unfiltered spikes?

I was planning to filter into a 50ml vial

 

[Ghoul]

And if the vial is already filtered?
Draw using unfiltered spikes?

I was planning to filter into a 50ml vial

Yep!

Unlike peptides, there's no major benefit of filtering oils at the last possible moment before use.

 

[Photon]

Yep!

Unlike peptides, there's no major benefit of filtering oils at the last possible moment before use.

How long can a spike be left on for?
I believe multi dose vials should be discarded after 28days (dont think anyone here does this)

Until the oil expires? A few years?

 

[Dunkirk]

For those that did filter oils, is it normal for the color to change?

Long story short, I had to transfer my oil to a new vial, figured why not filter it. The original vial had a yellowish (oily) color to it. After following it's much clearer now, with a very light yellow color. Is that normal?

 

[readalot]

For those that did filter oils, is it normal for the color to change?

Long story short, I had to transfer my oil to a new vial, figured why not filter it. The original vial had a yellowish (oily) color to it. After following it's much clearer now, with a very light yellow color. Is that normal?

Cool data point. If you filtered with 0.2 um it tells you there were color bodies >= 0.2 um that were imparting color to the original oil. Wild.