When conceived a quarter century ago, Sequential Injection was the first flow based analytical technique, based on flow programming (Ruzicka and Marshall 1990). Introducing such novel concept presented several difficulties, since there was neither software nor hardware suitable for this purpose.
While syringe pumps were available at that time, none of existing models could aspirate small discrete volumes at controlled and reversible flow rate. We had to design and fabricate our device, by using a peristaltic pump drive. It was a cam driven syringe pump that generated a sinusoidal flow rate (A).
Few years later, availability of Cavro pumps (B) made SI practical, ultimately leading to development of micro SI-LOV technique, which is now widely accepted as a platform for Sequential Injection and Bead Injection.
As the years passed, the miliGAT pump, invented by Duane Wolcott at Global FIA, became perfected (C). Its ingenious design allows synchronous refilling and provides a wide range of of flow rates. Its reliability is the result of meticulous engineering and of robust design. The combination of miliGAT pump with lab-on-valve in miniSIA-1 and miniSIA-2 instruments is a platform for automation of a variety of assays, as documented in this Chapter.
Yet, even the best, presently available pumps do have some shortcomings. Traditional syringe pumps (e.g. Cavro) have to be periodically refilled and their flow rate range is limited by the volume of the syringe. Miligat life is shortened if the pump is used to handle strong acids or bases.
Hopefully, all possibilities for pump design are not yet exhausted, and there will be found, one day, a simple solution how to construct an “ideal” drive for flow based assays.
J. Ruzicka & G.D. Marshall, Anal. Chim. Acta, 237, 329, (1990).
Is there an Ideal Pump?
2.2.40.
Once you have exhausted all possibilities and
failed, there will be one solution, simple and
obvious, highly visible to everyone else.
SNAFU
