Ammonia Assay by SFC
2.2.36.
Arresting reacting sample within a flow cell yields reaction rate curves, that can be used to quantify the content of target analyte. For the ammonia assay the sensitivity of the assay is adjusted by selecting length of the stop flow period and the temperature of flow cell. For this purpose the thermostated 13cm long Garth cell (A) was mounted on miniSIA-1 (B) system, supplied with salicylate and hypochlorite reagents (C), while DI water was used as a carrier.
The sandwich sequencing of sample with reagents is detailed in the assay protocol (D).
In order to optimize response to target analyte, the incubation period and temperature of the flow cell, temperature was varied while investigating the difference between responses of sample (100ppB N –panel E) and blank (panel F). The comparison of the thus obtained series of reaction rate curve indicates that for samples within the medium range (up to 800 ppM N) stop period of 45 seconds and temperature 40 C is suitable, while for high sensitivity assay, both stop flow period and temperature should be increased (see the next page.)
