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Field intercomparison of a novel optical sensor for formaldehyde quantification.

Geophysical research letters (2002-01-05)
S Friedfeld, M Fraser, D Lancaster, D Leleux, D Rehle, F Tittel
ABSTRACT

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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine hydrochloride, ≥98%
Supelco
O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine hydrochloride, for GC derivatization, LiChropur, ≥99.0% (AT)