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Submitted to: Sensors and Actuators B: Chemical
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/23/2007 Publication Date: 12/1/2007 Citation: Chen, G. 2007. Portable tetracycline analyzer based on LED-excitation europium-sensitized luminescence. Sensors and Actuators B: Chemical. Available:http:www.sciencedirect//doi:10.1016/j.snb.2007.10.046 Interpretive Summary: Tetracycline (TC) is a significant antibiotic extensively used in human and veterinary medicine. For clinical, environmental and food analyses, it is highly desirable to perform field analyses to obtain immediate results rather than merely to collect the samples and transport them to the laboratories. Europium-sensitized luminescence (ESL) is a highly sensitive and selective analytical technique for TC analysis. However, portable ESL instruments are not commercially available. An ultraviolet light emitting diode (UVLED) was used in this laboratory to develop a portable TC analyzer based on ESL. The optical, hardware and software design of this analyzer is discussed in detail in this manuscript. The instrument operation and data processing are controlled by a lap-top computer running an able, user-friendly custom program. The performance of the instrument is demonstrated using oxytetracycline as a model analyte. This analyzer, at 15 pounds, outperforms commercial bench-top instrument in sensitivity and portability. It is highly useful for field workers to perform agricultural and environmental analyses. Technical Abstract: A portable specific tetracycline (TC) analyzer was developed based on europium-sensitized luminescence (ESL) to perform field analysis. A 385 nm UV light emitting diode (LED) operated in pulsed mode is used as excitation source. In comparison to a conventional xenon flashlamp, its monochromatic emission and cleaner post-pulse extinction lead to reduced background and improved sensitivity. The time-resolved luminescence (TRL) signal is detected by a photomultiplier tube (PMT) that is gated to minimize its response to the LED pulse. The energy of individual LED pulses is monitored by a photodiode (PD) for signal normalization. Both instrument operation and data processing are controlled by a laptop computer running a custom LabVIEW program. The PD and the PMT signals are acquired at 4-µs time resolution and 12-bit amplitude resolution. The instrument design is discussed and its performance is evaluated using oxytetracycline, a significant member of the TC antibiotics, as a target analyte. The analyzer achieves a 0-3 ppm linear dynamic range (r2 = 0.9988) and a 0.021-ppb limit of detection with a typical 5% relative standard deviation. |
