Increased in back pressure during a run!

[koko]

The back pressure increased during a run up to 3000 psi then the system goes to 0 ml/min, when I restored the flow 1ml/min the back pressure is 2000 psi. What is causing this increased of back pressure.

What advice can give experts?

[TimB]

I'm not really an expert, but to me it sounds like something is clogging something. What happens when you change the column?

[skunked_once]

Koko,

You must provide much more information before we "experts" can make a wild guess. Please report your mobile phase(s), column packing and dimensions, etc. If this is a gradient run, provide the details. Why does the system go to 0 mL/min at 3,000 psi? Is it due to pressure shutdown? We eagerly await the details

[danko]

Hi Koko,

An expert without data is as useless as a non expert.
So, I think you’ll need to provide some data in exchange for hopefully plausible suggestions/advises.
F. ex.
1. What is the composition of the mobile phase?
2. What is the elution mode – gradient or isocratic?
3. Does the pressure rise upon sample injection, or would it rise if you just injected a mobile phase for instance?
4. What column are you using (i.e. diameter, length and particle size)?

Best Regards

[koko]

Sorry for omitting the data!

The method is isocratic, flow 1.0 ml/min, buffer pH 5.8(Sodium phosphate):methanol 70:30, the colum is C18 5um 100 x 4.6mm. and yes! the system goes to 0 ml/min due to pressure shutdown! The pressure increased only during the run.
I had no thought that could be the sample, because I the sample is filtered by membrane 0.45um.

[weeker2001]

maybe it is the reason of flow cell clogged .

[danko]

Hi Koko,

I’m inclined to believe that the sample is causing the trouble – even though you’re filtering the sample solution prior to injection. You see, many compounds are only soluble in certain solvents, at certain pH range etc. So, you can have a compound that is completely dissolved in your sample solution and yet precipitate upon contact with the mobile phase. And as you can figure out the expected outcome will be exactly what you’re experiencing in this case.
I have the following suggestion for you: Dissolve your sample in the mobile phase and observe the “solutionâ€

[sam.pedraglio]

koko, during your tests was the sample solved in the mobile fase?
If not and you pass danko's suggestion, try to solve your sample in the mobile phase and inject this.

[unmgvar]

what would be interesting to know is if the pressure increases during all the run or does it happen only at the beginning or only both?
chromatograms of pressures will be nice to have.
here are some common problems i have seen.

1. the mobile phase is bad. growing stuff in it simply clogg the column. change mobile phase.
2. sample does not solve in mobile phase and in large concentration actually "precipitate out" of solution. this means you have a very different solvent for the sample and mobile phase. dilute closer to mobile phase and if needed decrease concentration
3."stuff" from your sample eventhou you filter still goes through and like to agregate and it will always clogg capillary and columns over time, faster or slower depends on the "stuff". things that i have seen, proteins like collagen, gels like compounds from pills, micelle producing compounds.
4. your sample over time, especially if cooled and in high buffer concentration like to deposit at the bottom of the vial, and worst if in an insert and if your needle draws from close to the bottom of the vial or insert (especially) it will clogg. increase needle height.

you will probably also need to flush your system because most probably the capillaries and not only the column are clogging

[shahis77]

SAMPLE IS NOT CLEAR
MOBILE PHASE IS NOT CLEAR
SOMETHING GOT STUCK IN COLUMN OR FLOW CELL
SOMETHING IN NEEDLE

[koko]

Danko:

I´ll take your advice. No, I´m not working with proteins, I´m working in a dissolution test, I think that can be due to gelatine capsule.

I flush the system with water, without column and the pressure was 300 psi.

[LC_labrat]

What is the dissolution media? It could be the media precipitating out in the mobile phase.

[shahis77]

Gelatine cannot be a problem
are you filtering your samples before injecting them
.....your dissolution medium may also be the problem..

[koko]

I have seen the system, and without injection, the pressure of the system increased. The dissolution media that I am using is Gastric fluid (no enzymes), Intestinal Fluid(no enzymes), and acetate buffer pH 4.5, prepared like said the USP.

[shahis77]

check the instrument filters.....sonicate the filters in IPA