A flow-batch luminometer.

The traditional flow chemiluminescence (CL) systems typically use flow cells in spiral shape mounted in front of a photomultiplier tube (PMT). The sample is transported by using carrier fluids, undergoes dispersion, and mixes with reagents and CL reaction occurs before reaching the flow cell. As a consequence, the maximum of the chemiluminescence intensity is not exploited and the sensitivity is significantly diminished. In this work, these drawbacks were overcome by using a flow-batch approach and a large area silicon photodiode instead of PMT in order to build a simple and automatic luminometer for CL measurements. The feasibility of the proposed flow-batch luminometer was demonstrated in the determination of vitamin B12 in injection ampoules, yielding limits of detection and quantification (0.11 and 0.36 µg L–1, respectively), recovery rates (between 97.8 and 102.1%), relative standard deviations (RSD < 2.2%, n = 3) and sample throughput (about 72 h–1). Thus, it was possible to both project and build a simple, flexible, versatile and automatic luminometer, while keeping the excellent characteristics of the previous flow-batch analyzer such as: low reagent and sample consumption and minimal waste generation.