Jumping in here,
I have used low flow pumps in the past from this company.
http://www.hnp-mikrosysteme.de
A very good company to deal with also and offer excellent support.
I used this model
http://www.hnp-mikrosysteme.de/hnp-e...ure_series.htm to deliver a flow rate of about 30-80ul/min.
The pump is smaller than a white board marker. I don't know if your application may require the high pressure series of pumps of not.
Programmable controllers are available with the pump and according to data sheets will operate on 12v.
I used this model but it was running on a 24v supply being controlled by a PID loop,
http://www.hnp-mikrosysteme.de/pdf/p..._info_S-HD.pdf
Feed back was coming from a liquid flow meter.
If these pumps are looked after well they will preform excellently, if the additive you are pumping will adhere to the surfaces of the gears you will need to clean them after by running a solvent through the pumps, for the series i used 30mins at maximum speed suffices.
Best of luck.
D_G