Chromatography Forum

Dear Members

What is the good and efficient way to clean the HPLC injection port contaminated due to higher concentration of analyte injection

Flush with something in which your analyte is highly soluble.

Well, sometimes the material appears to diffuse in between the rotor and stator, that could take a lot of injector actuations to get it out again (only disassembling and washing of the parts got rid of, if I remember correctly, cortisol). In earlier chains some people even suggested that rotor teflon dissolves some analytes. For stubborn carryover we use an in-line ~0.8 mm inner diameter capillary (filled during stopped flow...) instead of a commercial injection port.

Jitender,

If you are using an autosampler you may have to lift the sample-intake needle and physically rub some cleaning solvent on the metalic piece where the needle seats or introduces the sample. This may require some disasembling.

If on the other hand you are doing manual injections, then things can be simpler. In this case make sure you flush the channel between the valve inlet and the valve rotor. For this operation there are small plastic pieces specially designed to do that with a syringe. Otherwise if you just introduce a solvent with a needle inserted into the valve, then you are not cleaning the initial part of the chanel between the valve and the rotor.

As someone mentioned before, if the contamination is severe, the rotor may have to be replaced. Some compounds can be absorbed on rotors made of Vespel, those made of Tefzel seem to be more inert.

Good Luck,

josebenjamin

Is there any influence of difference strength between injection port flushing solvent and mobile phase to the precision of replicate injections?

Dear
U should use same solvent for flushing, which is in ur mobile phase to avoid the problem. And if u r using different solvent for sample preparation u should inject Blank (sample solvent) two three times after finishing the analysis.
Hope it may help U

Raj B