Flow Injection Tutorial

The instrument (A) miniSIA-2 (Global FIA, WA, USA), comprises the following components:

Two miliGAT pumps, connected via two thermostated reaction coils to lab-on-valve module
Lab-on-valve module equipped with confluence point on central port
External flow cells for spectrophotometry, fluorescence or chemiluminescence ( shown here is cell for spectrophotometry)
Tungsten and LED (white) light sources
UV-VIS spectrophotometer (Ocean Optics)
Associated electronics, including coil heater control
All functions, data collection and evaluation are controlled and processed by customized software (FLOpro).

The two principal components of the instrument are the lab-on-valve module (B) and the miliGAT pump (C). This multipurpose instrument will function either in pFI or miniSI mode without need for physical reconfiguration.

The lab-on-valve, now widely used for miniSI applications, is modified for pFI applications by introducing a confluence point at the central port. Its critical function, mixing of sample with reagent is visualized (B) in three steps:

1) aspiration of sample (blue dye) into HC1,

2) transfer of sample from HC1 to HC2 while reagent (colorless acid) is being added at confluence point

3) transfer of reaction product (yellow) from HC2 into and trough the flow cell. This function is analogous to performance of confluence point in cF applications (1.2.15.)

The miliGAT pump (C) is built around four micro pistons riding on a sloped carousel. The flowrate is controlled by carousel rate of rotation and the delivered volume by number of rotations. The volume delivered per revolution , 630 microliters can be resolved into 504.811 steps. This results in unprecedented flowrate range of 40 nanoliters to 500 microliter/second, in either forward or reversed flow direction. Unlike all other syringe pumps, miliGAT does not require separate fill up period, because the rotating pistons aspirate fluids at the same rate as it is being delivered.