Hi Emanuele, Our column and pre-column(trap) equilibration goes up to 500 nl/min with 800 ba max pressure cap, and we run this for 5-10 min, we also do purge solvents and flush air to start with, while you are running it at 500 nl/min, isocratic at 50:50 A:B, disconnect the column out to union wait for flow for half min, connect it again, then disconnect the trap from the union and wait for flow to flush the union and then connect again, then connect the trap to T connection, disconnect waste line and column from T, let the let it flow for half min-min, then connect the column or emitter and let it flow for half min then connect the waste line, you can sonicate the T union in methanol or isopropanol for 5 min too, rinse it with HPLC grade water then and connect again, make sure there is no air before connecting the column or emitter, our droplet issue usually resolves by disconnecting waste line to T while on isocratic flow and then connect it again, make sure you are tightening it well but not too much. If this does not resolve the issue ,sonicate the tip, if you are running ug amount of samples on nano columns you will need to sonicate the tip every 10 days to avoid blocking it fast, we have a thermo tool which we use to hold the emitter/column tip on top of the beaker to sonicate the tip as I recommended in my 1st email, The next step would be adjusting the voltage and distance, if all of this does not help, check your source, it might be the spray source resistor has gone bad and need to be replaced and it's not applying right voltage in the tune setting to your column/source. That has happened to us one, and your service engineer should be able to fix the source, if the resistor is ok, check it on a new column /emitter then maybe your column tip or voltage connection is gone bad and you need to replace the column/emitter, all of this can be done in less than hour procedure. Please feel free to call me if you have any other questions, Good Luck, Khatereh Motamedchaboki, PhD. Director, Proteomics Facility Sanford Burnham Prebys Medical Discovery Institute 10901 North Torrey Pines Road La Jolla, CA 92037 Tel: (858) 646 3100 Ext: 3710 Fax: (858) 795 5221 http://www.sbpdiscovery.org/technology/sr/Pages/LaJolla_Proteomics.aspx -----Original Message----- From: ABRF Discussion Forum <email obscured>] On Behalf Of e.scollo Sent: Tuesday, February 09, 2016 11:39 AM To: <email obscured> Subject: Re: [ABRF Discussion Forum] Bubble forming at the tip of SS emitter for nano ESI Hi Kathered Thanks for your reply. I noticed that when I get the emitter very close to the source then the droplet disappear but then it forms again. Obviously I cannot have the emitter too close to the source otherwise the spray is not going to be stable, however I am not sure I understood well how you use the pump script to get rid of air. The flow on the nano pump is 300 nl/min so do you mean increasing the flow to remove air? Also how do I understand whether the issue is the emitter or not? Thanks Emanuele ―― View topic http://list.abrf.org/r/topic/3XBCw8m8h6lU3hWtMdQ5SU Leave group <email obscured>?Subject=Unsubscribe