Continuous Monitoring of Gaseous Formaldehyde Using an Improved Fluorescence Approach

Kelly, Thomas J.; Fortune, Christopher R.

doi:10.1080/03067319408034093

Cited by 70 publications

(53 citation statements)

References 20 publications

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“…A ThermoEnvironmental 42S chemiluminescent monitor was used to measure NO x and NO over a 200 ppb range. This monitor has a detection limit of 0.1 ppb and a response time of 10 s. HCHO was measured using a fluorescence monitor developed by Battelle (Kelly and Fortune, 1994;Pedditzi et al, 1999) that has a detection limit of 0.1 ppb and a response time of 90 s.…”

Section: Chemical Measurementsmentioning

confidence: 99%

A pilot study using scripted ventilation conditions to identify key factors affecting indoor pollutant concentration and air exchange rate in a residence

Johnson¹,

Myers

Kelly

et al. 2004

J Expo Sci Environ Epidemiol

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A pilot study was conducted using an occupied, single-family test house in Columbus, OH, to determine whether a script-based protocol could be used to obtain data useful in identifying the key factors affecting air-exchange rate (AER) and the relationship between indoor and outdoor concentrations of selected traffic-related air pollutants. The test script called for hourly changes to elements of the test house considered likely to influence air flow and AER, including the position (open or closed) of each window and door and the operation (on/off) of the furnace, air conditioner, and ceiling fans. The script was implemented over a 3-day period (January 30-February 1, 2002) during which technicians collected hourly-average data for AER, indoor, and outdoor air concentrations for six pollutants (benzene, formaldehyde (HCHO), polycyclic aromatic hydrocarbons (PAH), carbon monoxide (CO), nitric oxide (NO), and nitrogen oxides (NO x )), and selected meteorological variables. Consistent with expectations, AER tended to increase with the number of open exterior windows and doors. The 39 AER values measured during the study when all exterior doors and windows were closed varied from 0.36 to 2.29 h À1 with a geometric mean (GM) of 0.77 h À1 and a geometric standard deviation (GSD) of 1.435. The 27 AER values measured when at least one exterior door or window was opened varied from 0.50 to 15.8 h À1 with a GM of 1.98 h À1 and a GSD of 1.902. AER was also affected by temperature and wind speed, most noticeably when exterior windows and doors were closed. Results of a series of stepwise linear regression analyses suggest that (1) outdoor pollutant concentration and (2) indoor pollutant concentration during the preceding hour were the ''variables of choice'' for predicting indoor pollutant concentration in the test house under the conditions of this study. Depending on the pollutant and ventilation conditions, one or more of the following variables produced a small, but significant increase in the explained variance (R 2 -value) of the regression equations: AER, number and location of apertures, wind speed, air-conditioning operation, indoor temperature, outdoor temperature, and relative humidity. The indoor concentrations of CO, PAH, NO, and NO x were highly correlated with the corresponding outdoor concentrations. The indoor benzene concentrations showed only moderate correlation with outdoor benzene levels, possibly due to a weak indoor source. Indoor formaldehyde concentrations always exceeded outdoor levels, and the correlation between indoor and outdoor concentrations was not statistically significant, indicating the presence of a strong indoor source.

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Section: Chemical Measurementsmentioning

confidence: 99%

A pilot study using scripted ventilation conditions to identify key factors affecting indoor pollutant concentration and air exchange rate in a residence

Johnson¹,

Myers

Kelly

et al. 2004

J Expo Sci Environ Epidemiol

View full text Add to dashboard Cite

show abstract

“…These may be caused by species that are transferred into solution and in addition form photosensitive products that fluoresce in the same wavelength region as DDL. Cross sensitivity studies in the literature mainly deal with the role of higher aldehydes and ketones in forming alternative pyridines that could exhibit similar fluorescence spectra, or the influence of dissolved amines, competing with the formation of acetylacetoamine (Dong and Dasgupta, 1987;Dasgupta et al, 1988;Kelly and Fortune, 1994). In general, the interfering species have a lower solubility than HCHO and rather low concentrations in the background atmosphere, promoting an interference-free measurement of HCHO.…”

Section: Methodsmentioning

confidence: 99%

“…The instrument is based on the Hantzsch reagent method, initially used in a colorimetric technique by Nash (1953), following the design described in Kelly and Fortune (1994). In a first step, HCHO is stripped from a flow of 1 L/min (STP) of ambient air into 0.1 N H 2 SO 4 (0.45 ml min −1 ) in a stainless steel coil, temperature stabilized at 10 • C. The acidity of the stripping solution (pH ≈1) maximises the solubility of HCHO, and minimises the dissolution of ambient SO 2 , a potential interferent of the detection process.…”

Section: Methodsmentioning

confidence: 99%

Formaldehyde over the eastern Mediterranean during MINOS: Comparison of airborne in-situ measurements with 3D-model results

Kormann¹,

Fischer²,

Reus³

et al. 2003

Atmos. Chem. Phys.

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Abstract. Formaldehyde (HCHO) is an important intermediate product in the photochemical degradation of methane and non-methane volatile organic compounds. In August 2001, airborne formaldehyde measurements based on the Hantzsch reaction technique were performed during the Mediterranean INtensive Oxidant Study, MINOS. The detection limit of the instrument was 42 pptv (1σ ) at a time resolution of 180 s (10-90%). The overall uncertainty of the HCHO measurements was 30% at a mixing ratio of 300 pptv. In the marine boundary layer over the eastern Mediterranean Sea average HCHO concentrations were of the order of 1500 pptv, in reasonable agreement with results from a three-dimensional global chemical transport model of the lower atmosphere including non-methane volatile organic compound (NMVOC) chemistry. Above the boundary layer HCHO mixing ratios decreased with increasing altitude to a minimum level of 250 pptv at about 7 km. At higher altitudes (above 7 km) HCHO levels showed a strong dependency on the airmass origin. In airmasses from the North Atlantic/North American area HCHO levels were of the order of 300 pptv, a factor of 6 higher than values predicted by the model. Even higher HCHO levels, increasing to values of the order of 600 pptv at 11 km altitude, were observed in easterlies transporting air affected by the Indian monsoon outflow towards the Mediterranean basin. Only a small part (∼30 pptv) of the large discrepancy between the model results and the measurements of HCHO in the free troposphere could be explained by a strong underestimation of the upper tropospheric acetone concentration by up to a factor of ten by the 3D-model. Therefore, the measurement-model difference in the upper troposphere remains unresolved, while the observed dependency of HCHO on airmass origin might indicate that unknown, relatively long-lived NMVOCs -or their reaction intermediCorrespondence to: H. Fischer (hofi@mpch-mainz.mpg.de) ates -associated with biomass burning are at least partially responsible for the observed discrepancies.

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“…Formaldehyde was measured continuously using an instrument built in-house and based on the fluorescence technique described by Kelly and Fortune [1994]. HCHO The formaldehyde instrument was calibrated daily with liquid standards prepared from a serial dilution of a 0.3% stock formaldehyde solution.…”

Section: Methodsmentioning

confidence: 99%

Summertime formaldehyde at a high‐elevation site in Quebec

Macdonald¹,

Makar²,

Anlauf³

et al. 2001

J. Geophys. Res.

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Abstract. Measurements of formaldehyde were made during the summer of 1996 at a high-elevation site in Quebec as part of the North American Research Strategy on Tropospheric Ozone-Canada East (NARSTO-CE) measurement program. Gas phase mixing ratios were determined continuously by removing formaldehyde from the air in a glass coil scrubber, and producing a fluorescent dimer through the Hantzsch reaction. Average mixing ratios of formaldehyde were 1.3 and 0.8 ppbv for dry and wet periods, respectively. Highest values of HCHO were observed July 1-2 with a maximum mixing ratio of 4.6 ppbv. Fog water samples were also collected and analyzed for HCHO on five afternoon periods. Comparison of HCHO in the gas and aqueous phases shows reasonable agreement with Henry's law equilibrium. For dry periods July 1-12, relationships were examined between formaldehyde and other chemical species also measured at the site. Data were segregated based on the ratio of NOx to NOy and on the level of anthropogenic hydrocarbons present in the air mass. For the majority of the data, formaldehyde increased with both ozone and products of NOx oxidation (NOz) and was inversely related to the NOx/NOy ratio. During the high HCHO episode July 1-2, HCHO was correlated with neither ozone nor NOz illustrating the different chemistry at the site on these days. A chemical box model was used to examine sources of HCHO July 1-4. The model suggests that biogenic hydrocarbons contribute on average 53% of the locally produced formaldehyde, the remainder resulting from the oxidation of methane (19%), anthropogenic VOCs (16%), acetaldehyde (7%), and organic peroxides (3%). The model cannot account for the July 1-2 formaldehyde mixing ratios from the chemistry measured at the site. This implies that an additional HCHO source not included in the model was responsible for the high levels on those days. IntroductionFormaldehyde, the smallest and most plentiful atmospheric carbonyl compound, plays an important role in the oxidative balance of the atmosphere. Formaldehyde is the first stable product in the oxidation of methane, and in both the background troposphere and the marine atmosphere, methane is its dominant source. In the continental boundary layer, formaldehyde may also be produced via the oxidation of both anthropogenic and biogenic nonmethane hydrocarbons (also referred to as volatile organic compounds or VOCs). Primary sources of formaldehyde include direct emissions from combustion engines, manufacturing, or biomass burning [Warneck, 1988].The photolysis of formaldehyde (HCHO) or its reaction with OH is a source of the hydroperoxy radical in the atmosphere. At times, HCHO can be more important than ozone as a source of free radicals to the troposphere [Frost et al., 1998]. Since free radicals are the driving force in tropospheric chemistry, an understanding of formaldehyde sources and sinks is necessary in describing the chemistry of ozone and VOCs. Air This paper presents measurements of formaldehyde made at the Mt. Sutton site during the NARSTO-CE...

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Continuous Monitoring of Gaseous Formaldehyde Using an Improved Fluorescence Approach

Cited by 70 publications

References 20 publications

A pilot study using scripted ventilation conditions to identify key factors affecting indoor pollutant concentration and air exchange rate in a residence

A pilot study using scripted ventilation conditions to identify key factors affecting indoor pollutant concentration and air exchange rate in a residence

Formaldehyde over the eastern Mediterranean during MINOS: Comparison of airborne in-situ measurements with 3D-model results

Summertime formaldehyde at a high‐elevation site in Quebec

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