A simple, effective mixing chamber used in conjunction with a syringe pump for flow analysis

A simple, effective mixing chamber used in conjunction with a syringe pump for flow analysis is described and evaluated. A mixing chamber was constructed using a conventional 5 mL pipette tip and its performance compared with a widely used mixing coil. The results demonstrate that the mixing coil does not rapidly and completely mix solutions. Utilizing a configuration that reversed solution positions in the chamber with each mixing cycle, the proposed mixing chamber achieved complete mixing in a significantly shorter time than the mixing coil. The influence of injected sample volume on absorbance signals was evaluated by calculating an S_1/2 value for the system. As tested with a minimal rinse, the system has no discernable carryover. Testing this new approach in our previously described silicate measurement system resulted in a more than twofold improvement in sensitivity.