Characterization and use of a Raman liquid-core waveguide sensor using preconcentration principles.
A novel Raman sensor using a liquid-core optical waveguide is reported, implementing a Teflon-AF 2400 tube filled with water. An aqueous analyte mixture of benzene, toluene and p-xylene was introduced using a 1000 microl sample loop to the liquid-core waveguide (LCW) sensor and the analytes were preconcentrated on the inside surface of the waveguide tubing. The analytes were then eluted from the waveguide using an acetonitrile-water solvent mixture injected via a 30 microl eluting solvent loop. The preconcentration factor was experimentally determined to be 14-fold, in reasonable agreement with the theoretical preconcentration factor of 33 based upon the sample volume to elution volume ratio. Raman spectra of benzene, toluene and p-xylene were obtained during elution. It was found that analytically useful Raman signals for benzene, toluene and p-xylene were obtained at 992, 1004 and 1206 cm(-1), respectively. The relative standard deviation of the method was 3% for three replicate measurements. The limit of detection (LOD) was determined to be 730 ppb (parts per billion by volume) for benzene, exceptional for a system that does not resort to surface enhancement or resonance Raman approaches. The Raman spectra of these test analytes were evaluated for qualitative and quantitative analysis utility.
Tanikkul
Sumalee
S
Faculty of Science, Research and Development and Department of Chemistry, Institute of Science and Technology, Chiang Mai University, Chiang Mai, Thailand.
Jakmunee
Jaroon
J
Rayanakorn
Mongkon
M
Grudpan
Kate
K
Marquardt
Brian J
BJ
Gross
Gwen M
GM
Prazen
Bryan J
BJ
Burgess
Lloyd W
LW
Christian
Gary D
GD
Synovec
Robert E
RE