HPLC Static Mixers

[pdillon88]

Do many people change out their static mixers in order to get better signal to noise ratios?

[dap]

Afaik our team (20 HPLC Agilent 1200-1260) has never done it.

[Jake]

Yes. We gave up on the standard Shimadzu static mixers on our Shimadzu UHPLC due to too many problems, including bad 'pulsing' at very low-level detection by DAD. We struggled with this for awhile. Replaced them with a third party mixture and haven't had a problem since.

[tkubowicz]

Hello

You need to find good compromise. For example mixer can improve S/N when you use TFA in mobile phase but additional volume can affect fast gradient (method runtime).
For example: I've got gradient method with runtime 2 min (8 peaks) and baseline is quite noisy. However it is not affecting my results (separation/peak shape). Mixer improves baseline but I couldn't optimize method to be 2 min in total.

Agilent has triple JetWeaver to improve baseline (check it on website).

Regards

Tomasz Kubowicz

[DR]

I think Thermo-Fisher also sells "rifled" tubing pieces that do a fair job - or at least better than the bead stuffed column shells Agilent used to use.

[lmh]

Jake, can I ask what mixers you chose for the job? I have the same issue with a Shimadzu system, and spend a lot of time using reference wavelengths to try to get round the pulsing, but it's not ideal.

[janoshik]

Jake, can I ask what mixers you chose for the job? I have the same issue with a Shimadzu system, and spend a lot of time using reference wavelengths to try to get round the pulsing, but it's not ideal.

I am interested in this as well.

Shimadzu mixers are... Non-optimal, to mildly put it.

[Jake]

We tried all the various Shimadzu static mixers. They all performed poorly: very clear pulsing at low levels with DAD. We switched to Analytical Scientific Instruments static mixers and the issue went away. It was definitely the mixer, since when we re-installed the Shimadzu mixers, the problem returned. Currently we're using the ASI 350 uL HP. It has worked great for our application. They sell many types and have a pretty good guide for selecting the one best for your application. Choose carefully.

For what it's worth, we do NARP with RID with an Agilent 1100 quad pump. Even after bypassing the mixer, we were still having pulsing problems. We installed an ASI static mixer as a pulse dampener, and that has worked great.

Good luck.

[lmh]

Thanks for this! I appreciate the help.

[janoshik]

Thanks!

[Multidimensional]

Yes, the HPLC mixer should be optimized to the pump, flow rate, column type and application for best results. The manufacturer simply provides you with a "compromise" for general use. Please refer to this article for more info; "Appropriate Mixer Volume for HPLC and UHPLC Applications "; https://hplctips.blogspot.com/2014/10/a ... c-and.html