Hi members of Science,

I am a grad student at the university of Nebraska-Lincoln, USA. Our lab focuses more on native mass spec and top down proteomics. I am currently embedded in an ongoing project with ribosomal protein characterization.

I use micropipette type needles pulled at house by using a Sutter instruments, P97 tip puller for my nESI native work. The tips are 1 mm OD and 0.78 mm ID, borosilicate. I tried all the possible tip programs in the instrument to get a suitable tip size.

I have been trying to spray ribosomes under native conditions, now for months and unable to attain a stable spray which persists for few minutes. I am using 100 mM ammonium acetate with 0.5 mM mg.acetate as the buffer to suspend the native ribosomes. I used different additives like DMSO, TEAA for charge reduction, thinking that it will simplify the spectra and stabilize the spray, only to get discouraged at the end. What can I do to get a stable spray ?

Any ideas, suggestions or thoughts are appreciated !