Quantitative measurement of OH radical using Faraday rotation spectroscopy at 2.8 µm

2020 ◽  
Author(s):  
Weixiong Zhao ◽  
Bo Fang ◽  
Nana Wei ◽  
Nana Yang ◽  
Weijun Zhang ◽  
...  
Keyword(s):  
Faraday Rotation ◽  
Atmospheric Chemistry ◽  
Quantitative Measurement ◽  
High Sensitivity ◽  
Vital Role ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
Paramagnetic Species ◽  
Oh Radicals ◽  
Chemistry Research

<p>Hydroxyl (OH) radicals play a vital role in the degradation of trace gases and pollutants in the troposphere and in controlling the atmospheric oxidation capacity. Due to its short lifetime and low concentration, interference-free high sensitivity in situ OH monitoring by laser spectroscopy represents a challenge. In this presentation, we will report the development of Faraday rotation spectroscopy (FRS) instruments operating at 2.8 µm for quantitative measurement of OH concentrations in an atmospheric simulation chamber and the total atmospheric OH reactivity (k’<sub>OH</sub>). The Q (1.5) double lines (<sup>2</sup>Π<sub>3/2</sub> (ν=1<-0)) at 3568 cm<sup>-1</sup> were selected for the detection. Different detection methods have been studied. The FRS technology relies on the particular magneto-optic effect observed for paramagnetic species (including most radicals and some compounds with unpaired electrons), which can significantly reduce excess laser noise and makes it capable of enhancing the detection sensitivity and mitigation of spectral interferences from diamagnetic species in the atmosphere. With the use of a multipass enhanced FRS, a detection limit of 3.2 × 10<sup>6</sup> OH/cm<sup>3</sup> (2σ, 4s) was achieved with an absorption path length of 108 m. We demonstrated that FRS method provides a unique method for atmospheric chemistry research.</p>

High-sensitivity measurement of OH radicals using multi-pass enhanced Faraday Rotation Spectroscopy

2020 ◽  
Author(s):  
Tong Nguyen Ba ◽  
Weixiong Zhao ◽  
Jiajin Chen ◽  
Kun Liu ◽  
Xiaoming Gao ◽  
...  
Keyword(s):  
Faraday Rotation ◽  
High Sensitivity ◽  
Chem Phys ◽  
High Reactivity ◽  
Detection Sensitivity ◽  
Paramagnetic Species ◽  
Oh Radicals ◽  
Atmospheric Concentration ◽  
Wide Range ◽  
Key Factor

<p>The hydroxyl radical (OH) is considered as a primary agent responsible to remove a majority of trace gas in the atmosphere [1]. It is also responsible to initiate the reactions leading to the formation of a wide range of secondary species such as ozone (O<sub>3</sub>) and secondary organic aerosols (SOAs) [2]. Reliable and real-time assessment of the OH radical concentration change and related chemical process in the atmosphere is a key factor to understand and determinate the oxidation capacity of the atmosphere. Because of its very high reactivity, very short lifetime (≤ 1 s) associated with very low atmospheric concentration (~10<sup>6</sup> OH/cm<sup>3</sup>), the development of optical instrument allowing accurate, interference-free and ultra-high sensitivity in-situ direct measurement of OH concentration presents a great challenge for atmospheric science and climate change research.We report in this paper our recent development of an OH sensor based on Faraday Rotation Spectroscopy (FRS) [3]. FRS exploits magnetic circular birefringence (MCB) observed in the vicinity of Zeeman split absorption line of paramagnetic species such as O<sub>2</sub>, NO, NO<sub>2</sub>, OH. The Q(1,5e) and Q(1,5f) double lines of OH at 3568,52 cm<sup>-1</sup> and 3568,41 cm<sup>-1</sup> were chosen for quantification of OH radicals [4,5]. In order to enhance the detection sensitivity, multi-pass absorption approach was coupled to FRS. A 1σ (SNR=1) detection limit of about 5×10<sup>7</sup> OH/cm<sup>3</sup> was achieved.</p><p>The experimental detail and the preliminary results will be presented and discussed. </p><p><strong>Acknowledgments</strong></p><p>The authors thank the financial supports from the CPER CLIMIBIO program and the Labex CaPPA project (ANR-10-LABX005).</p><p> <strong>References</strong></p><p>[1] D.E. Heard, M.J. Pilling, Chem. Rev. <strong>103</strong> (2003) 5163-5198.</p><p>[2] D. Stone, L.K. Whalley, and D.E. Heard, Chem. Soc. Rev. <strong>41</strong> (2012) 6348-6404.</p><p>[3] G. Litfin, C.R. Pollock, R.F. Curl, F.K. Tittel, J. Chem. Phys. <strong>72</strong> (1980) 6602-6605.</p><p>[4] W. Zhao, G. Wysocki, W. Chen, et al., Opt. Express <strong>19</strong>, (2011) 2493-2501.</p><p>[5] W. Zhao, G. Wysocki, W. Chen, W. Zhang, Appl. Phys. B <strong>109</strong> (2012) 511-519.</p>

Novel Detection of Norovirus and Double Clostridium difficile in a Closed Cartridge System

2020 ◽  
Vol 16 (6) ◽  
pp. 954-964
Author(s):  
Hui Chen ◽  
Ziqi Xiao ◽  
Zhou Chu ◽  
Lian Jin ◽  
Song Li ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Supervisory Control ◽  
Detection Efficiency ◽  
High Sensitivity ◽  
High Specificity ◽  
Automatic Testing ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
Testing System ◽  
Automatic Testing System

Clostridium difficile infection (CDI) has become the main cause of diarrhea-related diseases in domestic (China) inpatients. High-sensitivity and high-specificity detection methods for CDI must be applied clinically for CDI supervisory control. In this paper, we introduce a detection method for C. difficile and Norovirus based on real-time PCR. We developed and optimized a primer–probe for Norovirus targets tcdA and tcdB with remarkably increased detection sensitivity. We then used this method in an integrated cassette, and found increased detection efficiency for Norovirus standards in the cassette compared to C. difficile samples. These results provide a basis for further exploration of automatic testing system design.

Atmospheric Chemistry of CH3CH2OCH3: Kinetics and Mechanism of Reactions with Cl Atoms and OH Radicals

2016 ◽  
Vol 49 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Mads P. Sulbaek Andersen ◽  
Sissel Bjørn Svendsen ◽  
Freja From Østerstrøm ◽  
Ole John Nielsen
Keyword(s):  
Atmospheric Chemistry ◽  
Kinetics And Mechanism ◽  
Oh Radicals ◽  
Cl Atoms

scholarly journals High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

2021 ◽  
Vol 11 (15) ◽  
pp. 6992
Author(s):  
Tie Zhang ◽  
Yuxin Xing ◽  
Gaoxuan Wang ◽  
Sailing He
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Continuous Monitoring ◽  
Near Infrared ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Industrial Applications ◽  
Detection Sensitivity ◽  
Infrared Range ◽  
Wavelength Modulation ◽  
Linear Coefficient

An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

Atmospheric chemistry of trans-CF3CHCHCl: Kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3

2008 ◽  
Vol 199 (1) ◽  
pp. 92-97 ◽  
Author(s):  
M.P. Sulbaek Andersen ◽  
E.J.K. Nilsson ◽  
O.J. Nielsen ◽  
M.S. Johnson ◽  
M.D. Hurley ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Oh Radicals ◽  
Gas Phase Reactions ◽  
Kinetics Of ◽  
Cl Atoms

Gold Immunochromatography Assay - A Newly Rapid Detection Technique for Aquatic Products

2013 ◽  
Vol 690-693 ◽  
pp. 1449-1454
Author(s):  
Yuan Wang ◽  
Hui Juan Yu ◽  
Bei Lei Qian ◽  
You Qiong Cai ◽  
Dong Mei Huang ◽  
...  
Keyword(s):  
Rapid Detection ◽  
High Sensitivity ◽  
Detection Technique ◽  
Detection Methods ◽  
Future Perspectives ◽  
Auxiliary Equipment ◽  
Basic Principles ◽  
Aquatic Products ◽  
Immunological Detection

Gold immunochromatography assay (GICA) technique has the following characteristics: rapid and simple, high sensitivity, good specificity, no auxiliary equipment, ease of interpreting results, and satisfactory stability. The technique has become one of the most rapid and sensitive immunological detection methods, which is widely used in medical, biological and other fields. The article focuses on the basic principles and technical characteristics of GICA, and briefly describes the applications and future perspectives in the rapid detection of aquatic products.

A rapid and accurate method for screening T-2 toxin in food and feed using competitive AlphaLISA

2021 ◽  
Vol 368 (6) ◽  
Author(s):  
Liwen Zhang ◽  
Qingyu Lv ◽  
Yuling Zheng ◽  
Xuan Chen ◽  
Decong Kong ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Accurate Method ◽  
Detection Methods ◽  
Cereal Crops ◽  
Detection Range ◽  
Highly Sensitive ◽  
Food And Feed ◽  
Good Repeatability ◽  
Feed Samples ◽  
Better Than

ABSTRACT T-2 is a common mycotoxin contaminating cereal crops. Chronic consumption of food contaminated with T-2 toxin can lead to death, so simple and accurate detection methods in food and feed are necessary. In this paper, we establish a highly sensitive and accurate method for detecting T-2 toxin using AlphaLISA. The system consists of acceptor beads labeled with T-2-bovine serum albumin (BSA), streptavidin-labeled donor beads and biotinylated T-2 antibodies. T-2 in the sample matrix competes with T-2-BSA for antibodies. Adding biotinylated antibodies to the test well followed by T-2 and T-2-BSA acceptor beads yielded a detection range of 0.03–500 ng/mL. The half-maximal inhibitory concentration was 2.28 ng/mL and the coefficient of variation was <10%. In addition, this method had no cross-reaction with other related mycotoxins. This optimized method for extracting T-2 from food and feed samples achieved a recovery rate of approximately 90% in T-2 concentrations as low as 1 ng/mL, better than the performance of a commercial ELISA kit. This competitive AlphaLISA method offers high sensitivity, good specificity, good repeatability and simple operation for detecting T-2 toxin in food and feed.

Highly sensitive and rapid detection of citrus Huanglongbing pathogen (Candidatus Liberibacter asiaticus) using Cas12a-based methods

2021 ◽  
Author(s):  
Matthew Wheatley ◽  
Yong-Ping Duan ◽  
Yinong Yang
Keyword(s):  
Early Detection ◽  
Nucleic Acids ◽  
Detection Sensitivity ◽  
Sensitive Detection ◽  
Detection Methods ◽  
Candidatus Liberibacter Asiaticus ◽  
Fluorescent Reporter ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus

Citrus Huanglongbing (HLB) or greening is one of the most devastating diseases of citrus worldwide. Sensitive detection of its causal agent, Candidatus Liberibacter asiaticus (CLas), is critical for early diagnosis and successful management of HLB. However, current nucleic acid-based detection methods are often insufficient for the early detection of CLas from asymptomatic tissue, and unsuitable for high-throughput and field-deployable diagnosis of HLB. Here we report the development of the Cas12a-based DETECTR (DNA endonuclease-targeted CRISPR trans reporter) assay for highly specific and sensitive detection of CLas nucleic acids from infected samples. The DETECTR assay, which targets the five-copy nrdB gene specific to CLas, couples isothermal amplification with Cas12a trans-cleavage of fluorescent reporter oligos and enables detection of CLas nucleic acids at the attomolar level. The DETECTR assay was capable of specifically detecting the presence of CLas across different infected citrus, periwinkle and psyllid samples, and shown to be compatible with lateral flow assay technology for potential field-deployable diagnosis. The improvements in detection sensitivity and flexibility of the DETECTR technology position the assay as a potentially suitable tool for early detection of CLas in infected regions.

scholarly journals Measurements of hydroperoxy radicals (HO<sub>2</sub>) at atmospheric concentrations using bromide chemical ionisation mass spectrometry

2019 ◽  
Vol 12 (2) ◽  
pp. 891-902 ◽  
Author(s):  
Sascha R. Albrecht ◽  
Anna Novelli ◽  
Andreas Hofzumahaus ◽  
Sungah Kang ◽  
Yare Baker ◽  
...  
Keyword(s):  
Water Vapour ◽  
Mass Spectrometer ◽  
Ion Source ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
Integration Time ◽  
Key Species ◽  
Atmospheric Concentrations ◽  
Chemical Ionisation ◽  
Ionisation Mass

Abstract. Hydroxyl and hydroperoxy radicals are key species for the understanding of atmospheric oxidation processes. Their measurement is challenging due to their high reactivity; therefore, very sensitive detection methods are needed. Within this study, the measurement of hydroperoxy radicals (HO2) using chemical ionisation combined with a high-resolution time-of-flight mass spectrometer (Aerodyne Research Inc.) employing bromide as the primary ion is presented. The sensitivity reached is equal to 0.005×108 HO2 cm−3 for 106 cps of bromide and 60 s of integration time, which is below typical HO2 concentrations found in the atmosphere. The detection sensitivity of the instrument is affected by the presence of water vapour. Therefore, a water-vapour-dependent calibration factor that decreases approximately by a factor of 2 if the water vapour mixing ratio increases from 0.1 % to 1.0 % needs to be applied. An instrumental background, most likely generated by the ion source that is equivalent to a HO2 concentration of (1.5±0.2)×108 molecules cm−3, is subtracted to derive atmospheric HO2 concentrations. This background can be determined by overflowing the inlet with zero air. Several experiments were performed in the atmospheric simulation chamber SAPHIR at the Forschungszentrum Jülich to test the instrument performance in comparison to the well-established laser-induced fluorescence (LIF) technique for measurements of HO2. A highly linear correlation coefficient of R2=0.87 is achieved. The slope of the linear regression of 1.07 demonstrates the good absolute agreement of both measurements. Chemical conditions during experiments allowed for testing the instrument's behaviour in the presence of atmospheric concentrations of H2O, NOx, and O3. No significant interferences from these species were observed. All of these facts demonstrate a reliable measurement of HO2 by the chemical ionisation mass spectrometer presented.

Atmospheric Chemistry of 2,3-Pentanedione: Photolysis and Reaction with OH Radicals

2011 ◽  
Vol 115 (33) ◽  
pp. 9160-9168 ◽  
Author(s):  
Emese Szabó ◽  
Mokhtar Djehiche ◽  
Matthieu Riva ◽  
Christa Fittschen ◽  
Patrice Coddeville ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Oh Radicals
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