title: Mid-ultraviolet light-emitting diode detects dipicolinic acid.
abstract: Dipicolinic acid (DPA, 2,6-pyridinedicarboxylic acid) is a substance uniquely present in bacterial spores such as that from anthrax (B. anthracis). It is known that DPA can be detected by the long-lived fluorescence of its terbium chelate; the best limit of detection (LOD) reported thus far using a large benchtop gated fluorescence instrument using a pulsed Xe lamp is 2 nM. We use a novel AlGaN light-emitting diode (LED) fabricated on a sapphire substrate that has peak emission at 291 nm. Although the overlap of the emission band of this LED with the absorption band of Tb-DPA (lambda(max) doublet: 273, 279 nm) is not ideal, we demonstrate that a compact detector based on this LED and an off-the-shelf gated photodetection module can provide an LOD of 0.4 nM, thus providing a basis for convenient early warning detectors.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, 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
authors.forename: M H
authors.initials: MH
authors.lastname: Crawford
authors.forename: A J
authors.initials: AJ
authors.lastname: Fischer
authors.forename: A A
authors.initials: AA
authors.lastname: Allerman
authors.forename: K H A
authors.initials: KH
authors.lastname: Bogart
authors.forename: S R
authors.initials: SR
authors.lastname: Lee
mesh_terms: D000336:Aerosols / Q000737:chemistry; D001408:Bacillus anthracis / Q000737:chemistry / Q000302:isolation & purification*; D008163:Luminescent Measurements; D010848:Picolinic Acids / Q000032:analysis / Q000302:isolation & purification*; D013056:Spectrophotometry, Ultraviolet / Q000295:instrumentation / Q000379:methods*; D013171:Spores, Bacterial / Q000737:chemistry / Q000302:isolation & purification*; D013725:Terbium
chemical_list: D000336:Aerosols; D010848:Picolinic Acids; D013725:Terbium; C004860:dipicolinic acid