Field intercomparison of a novel optical sensor for formaldehyde quantification.
A one-week in situ intercomparison campaign was completed on the Rice University campus for measuring HCHO using three different techniques, including a novel optical sensor based on difference frequency generation (DFG) operating at room temperature. Two chemical derivatization methods, 2,4-dinitrophenylhydrazine (DNPH) and o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA), were deployed during the daylight hours for three- to four-hour time-integrated samples. A real-time optical sensor based on laser absorption spectroscopy was operated simultaneously, including nighttime hours. This tunable spectroscopic source based on difference frequency mixing of two fiber-amplified diode lasers in periodically poled LiNb03 (PPLN) was operated at 3.5315 micrometers (2831.64 cm 1) to access a strong HCHO ro-vibrational transition free of interferences from other species. The results showed a bias of -1.7 and -1.2 ppbv and a gross error of 2.6 and 1.5 ppbv for DNPH and PFBHA measurements, respectively, compared with DFG measurements. These results validate the DFG sensor for time-resolved measurements of HCHO in urban areas.
Friedfeld
S
S
Department of Environmental Science and Engineering, Rice University, Houston Texas, USA.
Fraser
M
M
Lancaster
D
D
Leleux
D
D
Rehle
D
D
Tittel
F
F
D001272:Atmosphere / Q000737:chemistry*; D003624:Darkness; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D005069:Evaluation Studies as Topic; D005557:Formaldehyde / Q000032:analysis*; D006898:Hydroxylamines; D007834:Lasers; D055095:Optics and Photonics; D010659:Phenylhydrazines; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*; D005466:Fluorocarbons
D005557:Formaldehyde; D006898:Hydroxylamines; D010659:Phenylhydrazines; C004787:2,4-dinitrophenylhydrazine; C010277:Florox Reagent; D005466:Fluorocarbons