Design of a portable fluorometer capable of time-resolved luminescence measurements

摘要

A rugged, filter-based fluorometer capable of time-resolved luminescence (TRL) measurements was designed, prototyped and tested for field applications. The instrument operation and data processing were controlled by a laptop computer running a custom Lab VIEW program. A xenon flashlamp was used as the light source and a photomultiplier tube (PMT) as the photodetector. A gating technique was implemented to effectively overcome PMT saturation by intense xenon lamp flash so signal integrity was maintained even at very high gains, leading to improved sensitivity and reproducibility. The instrument was tested by TRL using tetracycline as a model analyte; and the signal was digitized at a 2-μs time resolution and a 12-bit amplitude resolution. Its performance was similar to or slightly better than that of a commercial fluorescence spectrophotometer. A 0-300 ppb linear dynamic range (r~2 = 0.9996) and a 0.025-ppb limit of detection (LOD) were achieved with a ≤ 5% relative standard deviation.