title: A time-gated fluorescence detector using a tuning fork chopper.
abstract: We describe an affordable gated fluorescence detection system to measure fluorescent compounds with long-lifetimes that uses a tuning fork chopper to block the intense excitation pulse from a flash lamp or short-lived fluorescence. A conventional non-gated inexpensive photosensor module is used to collect the luminescence signal. Using the long-lived luminescence from the terbium(III)-dipicolinic acid (DPA) chelate, we demonstrate a limit of detection (LOD) of 120pM for DPA. This system is not only an order of magnitude less expensive than an electronically gateable phototomultiplier tube (GPMT), it exhibits no evidence of gradual loss of sensitivity, due likely to photocathode fatigue and deterioration, observed with a GPMT.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, 700 Planetarium Place, Lubbock, TX 79409-1061, USA.
authors.forename: Qingyang
authors.initials: Q
authors.lastname: Li
authors.forename: Purnendu K
authors.initials: PK
authors.lastname: Dasgupta
authors.forename: Henryk
authors.initials: H
authors.lastname: Temkin
mesh_terms: D005453:Fluorescence; D005456:Fluorescent Dyes / Q000032:analysis*; D010848:Picolinic Acids / Q000032:analysis*; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods*; D013314:Stress, Mechanical; D013725:Terbium / Q000737:chemistry; D013997:Time Factors; D014159:Transducers; D014732:Vibration
chemical_list: D005456:Fluorescent Dyes; D010848:Picolinic Acids; D013725:Terbium; C004860:dipicolinic acid