title: LUMOS--A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range.
abstract: Most commercially available optical oxygen sensors target the measuring range of 300 to 2 μmol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized "sensing chemistry" that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a KSV of 6.25 x 10-3 ppmv-1. The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 μM down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented.
authors.affiliation: Institute Of Analytical Chemistry And Food Chemistry, Graz University Of Technology, NAWI Graz, Stremayrgasse 9, 8010 Graz, Austria.
authors.forename: Philipp
authors.initials: P
authors.lastname: Lehner
authors.affiliation: Institute Of Analytical Chemistry And Food Chemistry, Graz University Of Technology, NAWI Graz, Stremayrgasse 9, 8010 Graz, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Larndorfer
authors.affiliation: Department Of Biosciences, Aarhus University, 8000 Aarhus, Denmark.
authors.forename: Emilio
authors.initials: E
authors.lastname: Garcia-Robledo
authors.affiliation: Nordic Center For Earth Evolution, University Of Southern Denmark, 5230 Odense M, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Larsen
authors.affiliation: Institute Of Analytical Chemistry And Food Chemistry, Graz University Of Technology, NAWI Graz, Stremayrgasse 9, 8010 Graz, Austria.
authors.forename: Sergey M
authors.initials: SM
authors.lastname: Borisov
authors.affiliation: Department Of Biosciences, Aarhus University, 8000 Aarhus, Denmark.
authors.forename: Niels-Peter
authors.initials: NP
authors.lastname: Revsbech
authors.affiliation: Nordic Center For Earth Evolution, University Of Southern Denmark, 5230 Odense M, Denmark.
authors.forename: Ronnie N
authors.initials: RN
authors.lastname: Glud
authors.affiliation: Nordic Center For Earth Evolution, University Of Southern Denmark, 5230 Odense M, Denmark.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Canfield
authors.affiliation: Institute Of Analytical Chemistry And Food Chemistry, Graz University Of Technology, NAWI Graz, Stremayrgasse 9, 8010 Graz, Austria.
authors.forename: Ingo
authors.initials: I
authors.lastname: Klimant
mesh_terms: D005470:Fluorometry / Q000295:instrumentation*; D057230:Limit of Detection; D055096:Optical Devices; D009942:Organometallic Compounds / Q000737:chemistry; D010100:Oxygen / Q000032:analysis* / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D010165:Palladium; D010100:Oxygen