A Bubble-gating Flow Cell for Continuous-flow Analysis

Abstract

Abstract A system is described which permits measurements, such as photometry, to be made on air-segmented streams, as in continuous-flow analysis. Elimination of the "debubbler" step before measurement provides two basic assets: (1) more rapid attainment of steady-state conditions (lower interaction between samples), and (2) maintenance of the integrity of the bubbled analysis stream, permitting subsequent handling and remeasurement. A device has been developed for detecting air bubbles. When placed across the light path of a photometer flow cell it inactivates the readout system when bubbles pass by. The resulting system measures the transmittance of each individual liquid segment of the analysis stream, while maintaining the integrity of the stream. Two examples of possible applications of this system are described. One is a simple total-protein determination with biuret, at three times the conventional sampling rate. The other is a continuous-flow, two-point, reaction-rate method for assay of alkaline phosphatase activity.