A microSI-LOV system (A), for automated monitoring of ammonia (3–1200 ppm), glycerol: (20–120 ppm), glucose (35–1000) ppm and free iron (80–400 ppm) with spectrophotometric detection, was programmed to carry out reaction rate stopped flow measurement.
Sample (S) reagent (R) and spacer (Sp) were stacked into the holding coil (B) and the reaction mixture was carried into the flow cell where the flow was stopped. The red bar on stop flow recording (C) indicates stop flow period.
The assay of glucose is a two-step enzymatic reaction, the final product of which is NADH, monitored at 340 nm. The assay of glycerol is a two-step enzymatic reaction, of which the final product, Quinoneimine dye, is detected at 540 nm. Ammonia was assayed by means of Berthelot’s method, a two-step reaction sequence, where in the first step ammonia reacts with hypochlorite to form monochloramine. Next monochloramine reacts with phenol forming Indophenol Blue measured at 705 nm.
Free iron (II) forms a colored complex with ferrozine which is monitored at 560nm. This reaction is so fast that it reaches equilibrium even before the reaction mixture reaches the flow cell. Therefore, it can be monitored while sample flows through the cell without stopping the flow.
Reaction Rate for Fermentation Monitoring
2.4.7.
