title: Real-time, ultralow concentration detection of analytes in solution by infrared intracavity laser absorption.
abstract: Two intracavity laser absorption techniques for ultralow concentration detection of chemicals in solution are compared. The first consists of a laser diode in a grating extended cavity, which produces a linear calibration curve for parts in 10(9) (ppb) concentrations corresponding to 17 nM. By replacing the grating with a highly reflective mirror, parts in 10(12) (ppt) concentration detection is achieved, which corresponds to 340 pM. We report, to our knowledge for the first time, ppt detection of analyte concentration in liquid solution demonstrating good agreement between theory and experiment.
authors.affiliation: Institute of Photonics, University of Strathclyde, SUPA, Wolfson Centre, Glasgow, UK. untzizu.elejalde@strath.ac.uk
authors.forename: Untzizu
authors.initials: U
authors.lastname: Elejalde
authors.forename: John M
authors.initials: JM
authors.lastname: Girkin
mesh_terms: D000042:Absorption; D002138:Calibration; D004305:Dose-Response Relationship, Drug; D004867:Equipment Design; D000431:Ethanol / Q000737:chemistry; D005583:Fourier Analysis; D007834:Lasers; D012680:Sensitivity and Specificity; D012984:Software; D012996:Solutions; D013053:Spectrophotometry / Q000379:methods*; D013816:Thermodynamics
chemical_list: D012996:Solutions; D000431:Ethanol