Table 2.
Comparison of the main advantages and disadvantages of different flow formats for use in enzyme kinetics studies.
| Flow formats | Advantages | Disadvantages |
|---|---|---|
| Continuous flow | (i) The most simple system because of no requirement of extra part or flow manipulation | (i) Potential for low accuracy due to dispersion, dilution, and laminar flow effect (though, reports showed there are no significant problems) |
| (ii) High sample throughput with the least time consumption on flow operation | (ii) May be lower in sensitivity than other formats, if not enough reaction time due to high flow rate | |
|
| ||
| Stopped flow | (i) Improved sensitivity by increasing reaction time before detection | (i) Excessive stopped time may cause more dilution/dispersion of the reaction zone which will affect accuracy of the measurement |
| (ii) Possible to follow the reaction at various increments of stopped time which may give more information about the reaction | (ii) Lower sample throughput because of longer analysis time due to the stopped time prior to detection | |
|
| ||
| Quench flow | Same as stopped flow format | (i) Extra time consumption in collecting aliquots of quenched solutions for further analysis |
| (ii) The least automatic due to separated detection step | ||
| (iii) Requires quench solution to stop chemical reaction | ||
|
| ||
| Zone merging/bypass flow | (i) Possible to calculate for accurate concentration of the detected product because only the part of the mixing zone that is not effected by dispersion/dilution is detected | (i) Requires higher injected volume to gain adequate size of the product zone |
| (ii) More complicated arrangement, requires extra switching valve to change flow direction of the beginning and the end parts of the mixing zone, and needs precise time controlled operation | ||
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| ||
| Air segmented flow | (i) Accurate concentration because there is no dispersion, dilution, and or laminar flow effect on concentration measurement | (i) Requires SIA system to precisely control small volume air segment which may not be possible if use FIA system |
| (ii) Ensures measurement of initial rate | ||