Ambient formaldehyde detection with a laser spectrometer based on difference-frequency generation in PPLN

Rehle, D.; Leleux, D.; Erdélyi, Miklós; Tittel, Frank K.; Fraser, Matthew P.; Friedfeld, Stephen

doi:10.1007/s003400100549

Cited by 57 publications

(22 citation statements)

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“…This model has been designed by Weinstein and colleagues (13) that determines the changes in drug users' possible high risk behaviors and shows the probability of transmitting infection. The input data used in the model were collected by self-reported method from 259 IDUs in seven governmental MMT centers in Shiraz, south of Iran (Table 1).…”

Section: Methodsmentioning

confidence: 99%

Effectiveness of Methadone Maintenance Treatment in Prevention of Hepatitis C Virus Transmission among Injecting Drug Users

et al. 2013

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BackgroundInjecting drug users (IDUs) are a major and most important risk factor for rising hepatitis C virus (HCV) prevalence in Iran.ObjectivesThe objective of this study was to determine the effectiveness of methadone maintenance treatment (MMT) in prevention of HCV infection transmission among IDUs.Patients and MethodsA mathematical modeling has been used to estimate number of HCV infections averted. The input parameters used in the model were collected by self-reported method from 259 IDUs before registering and one year after MMT. Nonparametric statistical tests have been used to compare risky injecting and sexual behaviors among IDUs before and after participating in MMT program. Deterministic sensitivity analyses were done to show the effects of parameters’ uncertainty on outcome.ResultsOf the 259 participants, 98.4% (255) were men, the mean age ± SD was 33.1 ± 7.58 years and HCV prevalence was 50%. The studied IDUs reported lower rate of risky injecting and sexual behavior after participation in MMT program. The cumulative incidence of HCV per 100 IDUs due to sharing injection and unsafe sexual contact with MMT program were 13.84 (95% CI: 6.17 -21.51), 0.0003 (0.0001 - 0.0005) and without it 36.48 (25.84 - 47.11) and 0.0004 (0.0002-0.0006) respectively.ConclusionsThe MMT program is an effective intervention to prevent HCV infection transmission, although it is essential to compare its effectiveness with other interventions before implementing it in nationwide.

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Section: Methodsmentioning

confidence: 99%

Effectiveness of Methadone Maintenance Treatment in Prevention of Hepatitis C Virus Transmission among Injecting Drug Users

et al. 2013

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“…In order to determine the integrated absorbance A I (the area under the absorption line profile), absorption spectra were fitted to Voigt [32] and Galatry [33] profiles, using a Levenberg-Marquardt multi-line fitting algorithm. In the fit procedure, the baseline approximated with a 4th-order polynomial was experimentally found to well represent laser power ramp, allowing good removal of the variation of laser power in the fitted residual.…”

Section: Data Processing and Retrievalsmentioning

confidence: 99%

Measurement of the D/H, 18O/16O, and 17O/16O Isotope Ratios in Water by Laser Absorption Spectroscopy at 2.73 μm

Chen

Fertein

et al. 2014

Sensors

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A compact isotope ratio laser spectrometry (IRLS) instrument was developed for simultaneous measurements of the D/H, 18O/16O and 17O/16O isotope ratios in water by laser absorption spectroscopy at 2.73 μm. Special attention is paid to the spectral data processing and implementation of a Kalman adaptive filtering to improve the measurement precision. Reduction of up to 3-fold in standard deviation in isotope ratio determination was obtained by the use of a Fourier filtering to remove undulation structure from spectrum baseline. Application of Kalman filtering enables isotope ratio measurement at 1 s time intervals with a precision (<1‰) better than that obtained by conventional 30 s averaging, while maintaining a fast system response. The implementation of the filter is described in detail and its effects on the accuracy and the precision of the isotope ratio measurements are investigated.

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“…For example, Rehle et al [7] reported formaldehyde detection at 0.32 ppb using a 353 nm laser, and Richter et al [8] achieved a limit of detection of 74 ppt at 3.5 µm, but with a longer response time (1 minute rather than a few seconds). TDLS systems demonstrate good gas selectivity and signal-to-noise ratios, but are relatively expensive and complex to manufacture.…”

Section: Introductionmentioning

confidence: 97%

Formaldehyde sensor using non-dispersive UV spectroscopy at 340nm

Davenport

Hodgkinson

Saffell³

et al. 2014

SPIE Proceedings

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Formaldehyde is a volatile organic compound that exists as a gas at room temperature. It is hazardous to human health causing irritation of the eyes, nose and throat, headaches, limited pulmonary function and is a potential human carcinogen. Sources include incomplete combustion, numerous modern building materials and vehicle fumes. Here we describe a simple method for detecting formaldehyde using low resolution non-dispersive UV absorption spectroscopy for the first time. A two channel system has been developed, making use of a strong absorption peak at 339nm and a neighbouring region of negligible absorption at 336nm as a reference. Using a modulated UV LED as a light source and narrowband filters to select the desired spectral bands, a simple detection system was constructed that was specifically targeted at formaldehyde. A minimum detectable absorbance of 4.5 × 10 -5 AU was estimated (as ∆I/I 0 ), corresponding to a limit of detection of approximately 6.6 ppm for a 195mm gas cell, with a response time of 20s. However, thermallyinduced drift in the LED spectral output caused this to deteriorate over longer time periods to around 30 ppm or 2 × 10 -4 AU.

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Ambient formaldehyde detection with a laser spectrometer based on difference-frequency generation in PPLN

Cited by 57 publications

References 0 publications

Effectiveness of Methadone Maintenance Treatment in Prevention of Hepatitis C Virus Transmission among Injecting Drug Users

Effectiveness of Methadone Maintenance Treatment in Prevention of Hepatitis C Virus Transmission among Injecting Drug Users

Measurement of the D/H, 18O/16O, and 17O/16O Isotope Ratios in Water by Laser Absorption Spectroscopy at 2.73 μm

Formaldehyde sensor using non-dispersive UV spectroscopy at 340nm

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