LC vials

[bdhedhy19]

Just a simple question?
what would you recommend or prefer?!!!

LC vials with non slit septa or LC vials with slit septa?
I heard that LC vials with non slit septa gives OOS results, if the vials are filled to the neck, it creates vaccum or back pressure.

Thanks:)

[daniel_aut]

If your HPLC is reasonably clean, in a validated state and passes the daily performance verification, definitely use non slit vials.I don't know a situation where you could do otherwise(pharma and food industry are pretty clear on this topic).Every day maintenance is also very, very important

Now, if you are in a university lab or doing chromatography as a hobby, do the oposite.

[HPLCaddict]

Daniel, could you elaborate a bit on "pharma and food industry are pretty clear on this topic"? I'm not aware of any guideline stating that non-slit septa are a must in an regulated environment. And I don't know why the state of the HPLC is important for using non-slit septa.
Basically, I would first check the recommendations of the HPLC manufacturer. There are autosamplers with more or less "round" needles out there, which cannot really pierce non-slit septa very well. With those, it's a must to use slit septa.

[Peter Apps]

Just a simple question?
what would you recommend or prefer?!!!

LC vials with non slit septa or LC vials with slit septa?
I heard that LC vials with non slit septa gives OOS results, if the vials are filled to the neck, it creates vaccum or back pressure.

Thanks:)

The issue is not with the septa but with overfilling the vial. Slit septa leak around the needle while the sample is being withdrawn, so the headspace stays at atmospheric pressure. With a half-filled vial and a standard septum the pressure change is irrelevant anyway.

Peter

[lmh]

minor point: if you're using a system whose needle smashes through the septum like a knitting-needle, and you think there's any chance you might want to do a second injection from the same vial (later in the sequence, or the next day if the instrument has got stuck in the night), you might consider slit septa, which will survive the experience and re-seal a bit better. Otherwise non-slit septa are cheaper and work fine.

[bdhedhy19]

Thanks for your time:)

[Alfred88]

Dear daniel_aut:
I want to ask you more info on your "daily performance verification." What tests do you perform for what modules?
I am asking you because I know what must be done, and the time needed for the "performance verification." We need 2-3 days to complete all tests for our "performance verification." Our frequency is six months. Are you in USA? We have been audited year after year!

The title of the post is about LC vials. But then the actual question is about the septa/septum of the vial caps.
I have written about the risk of using the vial caps with non-cut septa on this forum a few times. I called it the "first injection penetration problem."
Perhaps daniel_aut is a newbie? Just start to learn the rope?

From my experience, you shall avoid the caps with non-cut septa. We have done that ~ 10 years ago.
I have seen needles of autosamplers (Shimadzu, Perkin-Elmer, etc) could not penetrate the septa, and the needles pushed the septa down into the vials.
I was in a supervisory position when I had to write two OOS investigations (~10 years ago) related to the vial caps.
The first OOS occurred when a chemist used the caps with non-cut septa on the Shimadzu HPLC. All vials had the first injections with significantly lower areas than the following injections. Prior to this OOS, we allocated the caps with non-cut septa for the Dionex HPLC, and the caps with pre-cut septa for the Shimadzu HPLC. As a CAPA from this OOS, we discard all caps without pre-cut septa, changed our SOPs, re-trained chemists.
The second OOS occurred because the vial caps without pre-cut septa were used. We ordered the right caps; however, the vendor made mistake and shipped some caps without pre-cut septa. Our CAPA was to inspect each shipment of vial caps, and remove/reject the wrong caps.

Thanks for reading. Today is Veteran Day in the USA. Thanks to those who served!

Alfred

[sisay]

Hi all

Another point of view for HPLC vial: how tightly should the cap be screwed? We have one method in which methanol is used as diluent and analyte is a volatile solvent. The result is OOS and the root cause may be that the analyte was evaporated from HPLC vial. Our chemist was taught to screw the cap very gently until it cannot be screwed further. In this case, it may not create vacuum pressure in the HPLC vial. However, it produces a leak for volatile solvent. After this investigation, chemist was taught to screw more tightly to avoid the evaporation.

So I am thinking that if we don’t even cap the vial for those non-volatile samples, will the results be the same or it depends on the mechanism of autosampler?

Thanks

[Blazer]

Regarding the screw cap vials, I never liked using them. I preferred the snap-cap style. I never had to worry about over-tightening them.

I've heard many people love the pre-slit septa. I seldom used them when I was in the lab, but can certainly see the benefit. Perhaps I've just been lucky in my career, but I've had no issues with the non-slit septa.

[Alfred88]

Dear sisay.
You asked about the "style" of the caps. There are three styles: snap on, screw on, and crimp.
The last style probably will work best for your case, but do not banish the screw caps. One more thing: verify for compatibility with your brand of autosampler, and verify there is no leechable from the septa.
Good luck.
Alfred

[sisay]

Dear sisay.
You asked about the "style" of the caps. There are three styles: snap on, screw on, and crimp.
The last style probably will work best for your case, but do not banish the screw caps. One more thing: verify for compatibility with your brand of autosampler, and verify there is no leechable from the septa.
Good luck.
Alfred

Hi Alfred88,

Thank you for the information, it is a useful reference for us to improve our analytical procedure in the future.