Electrospray ionisation

[hmparticle9]

In my Chemistry book, the following is said:

Electrospray ionisation - the sample is dissolved and pushed through a small nozzle at high pressure. A high voltage is applied to it, causing each particle to gain an $H^{+}$ ion. The sample is turned into a gas made up of positive ions.

I really would like a step by step explanation of the above. How does applying a voltage to the sample cause each particle to gain an $H^{+}$ ion?

 

[Borek]

In no way that's my area of expertise, but I don't think it is an accurate description.

Imagine a droplet leaving a nozzle - if the nozzle is at a high voltage, most droplets will be charged. That means they have an extra electron (or several), or they miss an electron (or several). These extra electrons (or non-electrons ;) ) have to be "stored" somewhere in the droplet. Unbalanced H⁺ are one way of the charged droplet to keep the charge (common one, no doubt about it), but definitely not the only one.

 

[hmparticle9]

Okay. I am basically a math guy that is trying to get into science.

If the nozzle is at a high voltage, the droplets will be charged. why?

I understand the extra/missing electrons when charged.

How does the $H^+$ "attach" itself to the sample?

Really explain your post like you are trying to explain it to a 5 year old. I am that level.

 

[Borek]

If the nozzle is at a high voltage, the droplets will be charged. why?

Physics 101 - basically high voltage always means charge separation (that's how you create a voltage - by moving charges apart, every joule of energy spent to move away a coulomb of charge produces 1 volt). If there is a voltage between two electrodes you can be sure both these electrodes have some extra charge on them. Identical charges repel, so charge carriers will happily jump on leaving droplets.

How does the $H^+$ "attach" itself to the sample?

More like it is somewhere "inside" of the sample.

Some molecules have groups with free electron pairs (water molecule for example, doesn't mean it is charged) which can reasonably easily accommodate a proton (which is what H⁺ actually is). These are places where an extra positive charge in the form of proton will most likely land. But in many cases these extra charges will disrupt something and will start some kind of decomposition of the molecule.