tip a linear relationship between the amount of sprayed analyte with the pulse width can be assumed the linear dynamic range with respect to absolute amount for bradykinin is tested from 29 attomole to 2900 attomole fig1 a 10 us to 1 ms pulse five mass spectra were recorded for each data point in fig1 a and the integrate peak area for the doubly protonated bradykinin molecule is calculated a relatively good linearity range of about 2 orders of magnitude is achieved with a 0 98512 r 2 value and standard deviation varies from 5 9 12 2 as the pulse width decrease from 10 us to 1 us the linearity of the signal intensity versus pulse width changes as shown in the inset of fig1 a and the signal intensity decrease much faster if we assume the nano esi tip has the same spray speed pl us in this time range 1 to 10 us as in the 10 us to 1 ms time range about 0 29 pl of the solution will be sprayed out of the tip for a 1 us pulse fig1 b shows the mass spectrum obtained for 2 9 attomole 1 us pulse bradykinin without any data processing such as averaging smoothing or filtering for bradykinin doubly protonated molecule m 2h 2 m z 531 shows the dominant peak in the mass spectrum singly charged molecule m h 1 m z 1060 can also be observed.