High sampling frequency, wide calibration range, and a high sensitivity, emphasized in this section are valuable features, yet, it is important to realize that there are several other important qualities of SI technique, which make it the first choice amongst all other flow based analytical techniques. These are:
Robustness and reliability. By reducing the number of mechanical components to single pump and single valve, the probability of a mechanical malfunction is minimized, servicing of the instrument is simplified, and the number of spare parts is limited.
Stability of flow, the Achilles Heel of peristaltic pumping, is no longer an issue, since syringe pumps generate precise, programmable flow rates over long periods of time and are capable of instant startup and shut down.
Low reagent consumption and waste generation. is inherent feature of SI methods, since reagents in microliter volumes are consumed only when the sample is being analyzed, and the carrier solution used is in almost all cases distilled water. The result is about ten times lower reagent consumption and waste generation. compared with all other flow based techniques,
Repeatibility and standardization of assays is achieved through combination of software controlled assay protocol, with a design of a well defined flow system, inherent in Lab-on-valve platform. In another words, all assays described in this section can be exactly reproduced, if carried out in the same apparatus, using the same software protocol and the same composition of reagents.
Readout–on–demand capability is the essential feature, necessary for monitoring of any system, within which a key chemical component undergoes a change. Thus if, e.g. a fermentation tank needs to be monitored for ammonia content in 15 minutes intervals over period of 24 hours, SI instrument can be programmed accordingly, to provide a readout each 15 minutes, while standing by idle when sample is not analyzed. The short response time (high sampling frequency), now available, allows immediate repetition of the assay should its result be in doubt.
SUMMARY
2.2.26.
