Flow splitting system

General Considerations. Some other important considerations that should be made when designing a flow splitting system are listed below. 

Specify feed nozzles choose pump and flow splitting system... 

Figure 4.52 Observed flow splitting performance for a 1000 pm X 100 pm micro channel system [31].

Many commercial split flow capillary LC systems incorporate a nano flow sensor mounted online to the capillary channel. The split flow system can be easily modified from a conventional system and performs satisfactorily for capillary LC applications. However, the split flow system may require thermal control and the LC solvent requires continuous degassing. In addition, the system may not work reliably at a high flow split ratios and at pressures above 6000 psi due to technical limitations of the fused silica thermal conductivity flow sensor. The split flow system based on conventional check valve design may not be compatible with splitless nano LC applications. The conventional ball-and-seat check valve is not capable of delivering nano flow rates and is not reliable for 7/24 operation at low flow. 

Three principal variations in the process design of DAF systems are full-flow, split-flow, and recycle operation (Fig. 14). Full-flow operation consists of pressurizing the entire waste... 

Once suitable ionization conditions have been established, LC separation can be optimized. As with any LC system, attention needs to be paid to column choice, correct tubing diameters, zero dead volume connections, use of guard columns, and mobile phase filtration and de-gassing. Modem LC pumps can deliver reliable gradients at low flow rates but for capillary LC, precolumn flow splitting or specialized pumps may be necessary. Mobile phase composition and pH should be chosen to... 

Yao et al. reported a flow injection analytical system for the simultaneous determination of acetylcholine and choline that made use of immobilized enzyme reactors and enzyme electrodes [25]. Acetylcholineesterase-choline oxidase and choline oxidase were separately immobilized by reaction with glutaraldehyde onto alkylamino-bonded silica, and incorporated in parallel as the enzyme reactors in a flow injection system. The sample containing acetylcholine and choline in 0.1 M phosphate buffer (pH 8.3) carrier solution was injected into the system. The flow was split to pass through the two reactors, recombined, and mixed with 0.3 mM K4Fe(CN)6 reagent solution before reaching a peroxidase immobilized electrode. Because each channel had a different residence time, two peaks were obtained for choline and total acetylcholine and choline. Response was linear for 5 pM-0.5 mM choline, and for 5 pM 1 mM acetylcholine plus choline. The detection limits were 0.4 pM for choline and 2 pM for acetylcholine. 

In our filtration system, the gas flow splits-up proportionally to the combined resistance encountered across the two possible pathways. 

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