spray problem

What kind of instrument/ion source? Also what kind/size of tips are you using? Do the drops tend to occur only at high organic? In my experience the culprit is usually one of the following: i) bad batch of tips (solution: try tips from new box), ii) air in LC stream (solution: purge and flush at high organic for a while), or iii) poorly cut fused-silica at junction close to the ion source (solution:break union, re-sleeve fused-silica tubing and make clean cut as last thing you do before putting the union back together. Be sure not to put a sleeve over the fused-silica after making cut). Thanks to Doug Simmons for providing this response.

Thank you for your reply Sir.we are using nano Lc (dionex) coupled with (bruker daltonik) mass spectrometer.The size of the needle is 10um which is recommented by bruker. The company we are using for needle is Picotip emitter .we are using nano online source.i check all things that you told.when we changed the new needle spray is good.Spray is good only 5 or 6 samples.After that i becomes drops..

From my experience, usually either the sample or the solvents have particulates which will clog the tip. Check to make sure, your solvents are filtered and there is no floaters in them. [i]Thanks to Kutralanathan Renganathan for this response to LabWrench[/i]

Thank you for your reply.I will check it and tell you.

Hi, Do you use any organic solvent in channel A? A few percentage of acetonitril can drastically improve the spray stability. Another point of consideration is desalting of the samples. Is this done on-line or off-line?

No Sir. we use only HPLC water and 0.005% Fa in channel A. we are using nano On-Line sources. samples are well filtered.

Hello Sir.Good morning. i had an problem in LC (ie high back pressure in micro pump).how it can be reduced. i had done two method to reduce the pressure in micro pump.but still pressure is high. cleaning the column with acetonitrile with 90% overnight waste cleaning the check valve and rotor