scholarly journals Evidence and quantitation of aromatic organosulfates in ambient aerosols in Lahore, Pakistan

2012 ◽  
Vol 12 (12) ◽  
pp. 32795-32823 ◽  
Author(s):  
S. Kundu ◽  
T. A. Quraishi ◽  
G. Yu ◽  
C. Suarez ◽  
F. N. Keutsch ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Matrix Effects ◽  
Fine Particulate Matter ◽  
Standard Addition ◽  
Ultra Performance Liquid Chromatography ◽  
Mass Measurements ◽  
Ambient Aerosols ◽  
Volatile Organic ◽  
Secondary Reactions ◽  
Negative Electrospray Ionization

Abstract. Organosulfates are important components of atmospheric organic aerosols, yet their structures, abundances, sources and formation processes are not adequately understood. This study presents the identification and quantitation of benzyl sulfate in atmospheric aerosols, which is the first reported atmospheric organosulfate with aromatic carbon backbone. Benzyl sulfate was identified and quantified in fine particulate matter (PM2.5) collected in Lahore, Pakistan during 2007–2008. An authentic standard of benzyl sulfate was synthesized, standardized, and identified in atmospheric aerosols using ultra-performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight (Q-ToF) mass spectrometry (MS). Benzyl sulfate was quantified in aerosol samples using UPLC coupled to negative electrospray ionization triple quadrupole (TQ) MS. The highest benzyl sulfate concentrations were recorded in November and January 2007 (0.50 ± 0.11 ng m−3) whereas the lowest concentration was observed in July (0.05 ± 0.02 ng m−3). To evaluate matrix effects, benzyl sulfate concentrations were determined using external calibration and the method of standard addition; comparable concentrations were detected by the two methods, which ruled out significant matrix effects in benzyl sulfate quantitation. Three additional organosulfates with m/z 187, 201 and 215 were qualitatively identified as aromatic organosulfates with additional methyl substituents by high-resolution mass measurements and tandem MS. The observed aromatic organosulfates form a homologous series analogous to toluene, xylene, and trimethylbenzene, which are abundant anthropogenic volatile organic compounds (VOC), suggesting that aromatic organosulfates may be formed by secondary reactions. Further studies are needed to elucidate the sources and formation pathways of aromatic organosulfates in the atmosphere.

scholarly journals Evidence and quantitation of aromatic organosulfates in ambient aerosols in Lahore, Pakistan

2013 ◽  
Vol 13 (9) ◽  
pp. 4865-4875 ◽  
Author(s):  
S. Kundu ◽  
T. A. Quraishi ◽  
G. Yu ◽  
C. Suarez ◽  
F. N. Keutsch ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Matrix Effects ◽  
Fine Particulate Matter ◽  
Standard Addition ◽  
Ultra Performance Liquid Chromatography ◽  
Ambient Aerosols ◽  
Statistical Correlations ◽  
Atmospheric Processing ◽  
Secondary Reactions ◽  
Negative Electrospray Ionization

Abstract. Organosulfates are important components of atmospheric organic aerosols, yet their structures, abundances, sources and formation processes are not adequately understood. This study presents the identification and quantitation of benzyl sulfate in atmospheric aerosols, which is the first confirmed atmospheric organosulfate with aromatic carbon backbone. Benzyl sulfate was identified and quantified in fine particulate matter (PM2.5) collected in Lahore, Pakistan, during 2007–2008. An authentic standard of benzyl sulfate was synthesized, standardized, and identified in atmospheric aerosols with quadrupole time-of-flight (Q-ToF) mass spectrometry (MS). Benzyl sulfate was quantified in aerosol samples using ultra performance liquid chromatography (UPLC) coupled to negative electrospray ionization triple quadrupole (TQ) MS. The highest benzyl sulfate concentrations were recorded in November and January 2007 (0.50 ± 0.11 ng m−3) whereas the lowest concentration was observed in July (0.05 ± 0.02 ng m−3). To evaluate matrix effects, benzyl sulfate concentrations were determined using external calibration and the method of standard addition; comparable concentrations were detected by the two methods, which ruled out significant matrix effects in benzyl sulfate quantitation. Three additional organosulfates with m/z 187, 201 and 215 were qualitatively identified as aromatic organosulfates with additional methyl substituents by high-resolution mass measurements and tandem MS. The observed aromatic organosulfates form a homologous series analogous to toluene, xylene, and trimethylbenzene, which are abundant anthropogenic volatile organic compounds (VOC), suggesting that aromatic organosulfates may be formed by secondary reactions. However, stronger statistical correlations of benzyl sulfate with combustion tracers (EC and levoglucosan) than with secondary tracers (SO42− and α-pinene-derived nitrooxy organosulfates) suggest that aromatic organosulfates may be emitted from the combustion sources or their subsequent atmospheric processing. Further studies are needed to elucidate the sources and formation pathways of aromatic organosulfates in the atmosphere.

scholarly journals Simultaneous quantification method for 5-FU, uracil, and tegafur using UPLC-MS/MS and clinical application in monitoring UFT/LV combination therapy after hepatectomy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ken Shiraiwa ◽  
Yosuke Suzuki ◽  
Hiroki Uchida ◽  
Yukio Iwashita ◽  
Ryota Tanaka ◽  
...  
Keyword(s):  
Adverse Effects ◽  
Combination Therapy ◽  
Human Plasma ◽  
Matrix Effects ◽  
Ultra Performance Liquid Chromatography ◽  
Therapeutic Drug ◽  
Simultaneous Quantification ◽  
Ionization Mode ◽  
Time Courses ◽  
Negative Electrospray Ionization

AbstractCombination therapy of tegafur/uracil (UFT) and leucovorin (LV) is widely used to treat colorectal cancers. Although this therapy has a significant therapeutic effect, severe adverse effects occur frequently. Therapeutic drug monitoring (TDM) may help to prevent adverse effects. A useful assay that can quantitate plasma levels of 5-FU, uracil, and tegafur simultaneously for TDM has been desired, but such a method is not currently available. In this study, we aimed to develop a sensitive method for simultaneous quantification of 5-FU, uracil, and tegafur in human plasma using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). After preparing plasma samples by protein precipitation and liquid extraction, 5-FU, uracil, and tegafur were analyzed by UPLC-MS/MS in negative electrospray ionization mode. Validation was performed according to US Food and Drugs Administration guidance. The calibration curves were linear over concentration ranges of 2–500 ng/mL for 5-FU, 20–5000 ng/mL for uracil, and 200–50,000 ng/mL for tegafur. The corresponding average recovery rates were 79.9, 80.9, and 87.8%. The method provides accuracy within 11.6% and precision below 13.3% for all three analytes. Matrix effects of 5-FU, uracil, and tegafur were higher than 43.5, 84.9, and 100.2%, respectively. This assay was successfully applied to assess the time courses of plasma 5-FU, uracil, and tegafur concentrations in two patients with colorectal liver metastasis who received UFT/LV therapy after hepatectomy. In conclusion, we succeeded to develop a sensitive and robust UPLC-MS/MS method for simultaneous quantification of 5-FU, uracil, and tegafur in human plasma. This method is potentially useful for TDM in patients receiving UFT/LV combination therapy.

scholarly journals Development, characterization and first deployment of an improved online reactive oxygen species analyzer

2017 ◽  
Author(s):  
Jun Zhou ◽  
Emily A. Bruns ◽  
Peter Zotter ◽  
Giulia Stefenelli ◽  
André S. H. Prévôt ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Detection Limit ◽  
Atmospheric Aerosols ◽  
Matrix Effects ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Wood Combustion ◽  
Ambient Aerosols ◽  
Storage Duration ◽  
High Concentrations

Abstract. Inhalation of atmospheric particles is linked to human diseases. Reactive oxygen species (ROS) present in these atmospheric aerosols may play an important role. However, the ROS content in aerosols and their formation pathways are still largely unknown. Here, we have developed an online and offline ROS analyzer using a 2’,7’-dichlorofluorescin (DCFH) based assay. The sensitivity of the ROS analyzer was characterized using a suite of model organic compounds. The instrument detection limit determined as three times the noise is 1.3 nmol L−1 for offline analysis and 2 nmol m−3 of sampled air when the instrument is operated online at a fluorescence response time of approximately 8 min, while the offline method detection limit is 9 nmol L−1 to 13 nmol L−1. Potential interferences from gas phase O3 and NOx, matrix effects of particulate SO42− and NO3− were tested, but not observed. Fe3+ had no influence on the ROS signal while soluble Fe2+ reduced it if present at high concentrations in the extracts. Both online and offline methods were applied to identify the ROS content of different aerosol types, i.e., ambient aerosols as well as fresh and aged aerosols from wood combustion emissions. The stability of the ROS was assessed by comparing the ROS concentration measured by the same instrumentation online in-situ with offline measurements. We also analyzed the evolution of ROS in specific samples by conducting the analysis after storage times of up to four months. The ROS were observed to decay with increasing storage duration. From their decay behavior, ROS in secondary organic aerosol (SOA) can be separated into short- and long-lived fractions, with an average half-life of ~ 1.7 h and ~ 432 d, respectively. All these measurements showed consistently that, on average 60 ± 20 % of the ROS were very reactive and disappeared during the filter storage time. This demonstrates the importance of a fast online measurement of ROS.

scholarly journals Organosulfates in atmospheric aerosols in Shanghai, China: seasonal and interannual variability, origin, and formation mechanisms

2020 ◽  
Author(s):  
Yao Wang ◽  
Yue Zhao ◽  
Yuchen Wang ◽  
Jian-Zhen Yu ◽  
Jingyuan Shao ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Atmospheric Aerosols ◽  
Dominant Role ◽  
Fine Particulate Matter ◽  
Eastern China ◽  
Anthropogenic Pollution ◽  
Liquid Water Content ◽  
Urban Site ◽  
Formation Mechanisms ◽  
Ambient Aerosols

Abstract. Organosulfates (OS) are ubiquitous in the atmosphere and serve as important tracers for secondary organic aerosols (SOA). Despite intense research over years, the abundance, origin, and formation mechanisms of OS in ambient aerosols, in particular in regions with severe anthropogenic pollution, are still not well understood. In this study, we collected filter samples of ambient fine particulate matter (PM2.5) over four seasons in both 2015/2016 and 2018/2019 at an urban site in Shanghai, China, and comprehensively characterized the OS species in these PM2.5 samples using a liquid chromatography coupled to a high resolution mass spectrometer (UPLC-ESI-QToF-MS). We find that while the concentration of organic aerosol (OA) decreased by 29 % in 2018/2019, compared to that in 2015/2016, the annually averaged concentrations of 35 quantified OS were similar in two years (65.5 ± 77.5 ng m−3 in 2015/2016 versus 59.4 ± 79.7 ng m−3 in 2018/2019), suggesting an increased contribution of SOA to OA in 2018/2019 than in 2015/2016. Isoprene- and monoterpene-derived OS are the two most abundant OS families, on average accounting for 36.3 % and 31.0 % of the quantified OS concentrations, respectively, suggesting an important contribution of biogenic emissions to the production of OS and SOA in Shanghai. The abundance of biogenic OS, particularly those arising from isoprene, exhibited strong seasonality (peaked in summer) but no significant interannual variability. In contrast, anthropogenic OS such as diesel-derived ones had little seasonal variability and declined obviously in 2018/2019 compared with that in 2015/2016. This reflects a significant change in precursor emissions in eastern China in recent years. The C2/C3 OS species that have both biogenic and anthropogenic origins averagely contributed to 19.0 % of the quantified OS, with C2H3O6S−, C3H5O5S−, and C3H5O6S− being the most abundant ones, together accounting for 76 % of C2/C3 OS concentrations. 2-Methyltetrol sulfate (2-MT-OS, C5H11O7S−) and monoterpene-derived C10H16NO7S− were the most abundant OS and nitrooxy-OS in summer, contributing to 31 % and 5 % of the quantified OS, respectively. The substantially larger concentration ratio of 2-MT-OS to 2-methylglyceric acid sulfate (2-MA-OS, C4H7O7S−) in summer (6.8–7.8) than in other seasons (0.31–0.78) implies that low-NOx oxidation pathways played a dominant role in isoprene-derived SOA formation in summer, while high-NOx reaction pathways were more important in other seasons. We further find that the production of OS was largely controlled by the level of Ox (Ox = O3 + NO2), namely, the photochemistry of OS precursors, in particular in summer, though sulfate concentration, aerosol acidity, as well as aerosol liquid water content (ALWC) that could affect the heterogeneous chemistry of reactive intermediates leading to OS formation also played a role. Our study provides valuable insights into the characteristics and mechanisms of OS formation in a typical Chinese megacity and implies that mitigation of Ox pollution can effectively reduce the production of OS and SOA in eastern China.

scholarly journals Aging of atmospheric aerosols and the role of iron in catalyzing brown carbon formation

2021 ◽  
Author(s):  
Hind A. A. Al-Abadleh
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Atmospheric Aerosols ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Atmospheric Oxidation ◽  
Carbon Formation ◽  
Brown Carbon ◽  
Volatile Organic

Extensive research has been done on the processes that lead to the formation of secondary organic aerosol (SOA) including atmospheric oxidation of volatile organic compounds (VOCs) from biogenic and anthropogenic...

scholarly journals Trends in PM2.5 Concentration in Nagoya, Japan, from 2003 to 2018 and Impacts of PM2.5 Countermeasures

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 590
Author(s):  
Makiko Yamagami ◽  
Fumikazu Ikemori ◽  
Hironori Nakashima ◽  
Kunihiro Hisatsune ◽  
Kayo Ueda ◽  
...  
Keyword(s):  
Fine Particulate Matter ◽  
Control Measures ◽  
Source Control ◽  
Atmospheric Concentration ◽  
Construction Machinery ◽  
Emission Regulations ◽  
Volatile Organic ◽  
Stationary Sources ◽  
Pm2.5 Concentration

In Japan, various countermeasures have been undertaken to reduce the atmospheric concentration of fine particulate matter (PM2.5). We evaluated the extent to which these countermeasures were effective in reducing PM2.5 concentrations by analyzing the long-term concentration trends of the major components of PM2.5 and their emissions in Nagoya City. PM2.5 concentrations decreased by 53% over the 16-year period from fiscal years 2003 to 2018 in Nagoya City. Elemental carbon (EC) was the component of PM2.5 with the greatest decrease in concentration over the 16 years, decreasing by 4.3 μg/m3, followed by SO42− (3.0 μg/m3), organic carbon (OC) (2.0 μg/m3), NH4+ (1.6 μg/m3), and NO3− (1.3 μg/m3). The decrease in EC concentration was found to be caused largely by the effect of diesel emission control. OC concentrations decreased because of the effects of volatile organic compound (VOC) emission regulations for stationary sources and reductions in VOCs emitted by vehicles and construction machinery. NO3− concentrations decreased alongside decreased contributions from vehicles, construction machinery, and stationary sources, in descending order of the magnitude of decrease. Although these findings identify some source control measures that have been effective in reducing PM2.5, they also reveal the ineffectiveness of some recent countermeasures for various components, such as those targeting OC concentrations.

scholarly journals Anthropogenic enhancements to production of highly oxygenated molecules from autoxidation

2019 ◽  
Vol 116 (14) ◽  
pp. 6641-6646 ◽  
Author(s):  
Havala O. T. Pye ◽  
Emma L. D’Ambro ◽  
Ben H. Lee ◽  
Siegfried Schobesberger ◽  
Masayuki Takeuchi ◽  
...  
Keyword(s):  
Fine Particulate Matter ◽  
Peroxy Radicals ◽  
Dominant Component ◽  
Fine Particulate ◽  
Biogenic Voc ◽  
Aircraft Observations ◽  
Volatile Organic ◽  
Climate Interactions ◽  
Urban Plume

Atmospheric oxidation of natural and anthropogenic volatile organic compounds (VOCs) leads to secondary organic aerosol (SOA), which constitutes a major and often dominant component of atmospheric fine particulate matter (PM2.5). Recent work demonstrates that rapid autoxidation of organic peroxy radicals (RO2) formed during VOC oxidation results in highly oxygenated organic molecules (HOM) that efficiently form SOA. As NOxemissions decrease, the chemical regime of the atmosphere changes to one in which RO2autoxidation becomes increasingly important, potentially increasing PM2.5, while oxidant availability driving RO2formation rates simultaneously declines, possibly slowing regional PM2.5formation. Using a suite of in situ aircraft observations and laboratory studies of HOM, together with a detailed molecular mechanism, we show that although autoxidation in an archetypal biogenic VOC system becomes more competitive as NOxdecreases, absolute HOM production rates decrease due to oxidant reductions, leading to an overall positive coupling between anthropogenic NOxand localized biogenic SOA from autoxidation. This effect is observed in the Atlanta, Georgia, urban plume where HOM is enhanced in the presence of elevated NO, and predictions for Guangzhou, China, where increasing HOM-RO2production coincides with increases in NO from 1990 to 2010. These results suggest added benefits to PM2.5abatement strategies come with NOxemission reductions and have implications for aerosol–climate interactions due to changes in global SOA resulting from NOxinteractions since the preindustrial era.

Development of Certified Reference Materials for Diarrhetic Shellfish Poisoning Toxins, Part 2: Shellfish Matrix Materials

2016 ◽  
Vol 99 (5) ◽  
pp. 1163-1172 ◽  
Author(s):  
Pearse McCarron ◽  
Kelley L Reeves ◽  
Sabrina D Giddings ◽  
Daniel G Beach ◽  
Michael A Quilliam
Keyword(s):  
Reference Materials ◽  
Matrix Effects ◽  
Certified Reference Materials ◽  
Standard Addition ◽  
Tissue Homogenate ◽  
Shellfish Poisoning ◽  
Diarrhetic Shellfish Poisoning ◽  
Preliminary Work ◽  
Seafood Industry ◽  
Human Illness

Abstract Okadaic acid (OA) and its analogs, dinophysistoxins-1 (DTX1) and -2 (DTX2) are lipophilic biotoxins produced by marine algae that can accumulate in shellfish and cause the human illness known as diarrhetic shellfish poisoning (DSP). Regulatory testing of shellfish is required to protect consumers and the seafood industry. Certified reference materials (CRMs) are essential for the development, validation, and quality control of analytical methods, and thus play an important role in toxin monitoring. This paper summarizes work on research and development of shellfish tissue reference materials for OA and DTXs. Preliminary work established the appropriate conditions for production of shellfish tissue CRMs for OA and DTXs. Source materials, including naturally incurred shellfish tissue and cultured algae, were screened for their DSP toxins. This preliminary work informed planning and production of a wet mussel (Mytilus edulis) tissue homogenate matrix CRM. The homogeneity and stability of the CRM were evaluated and found to be fit-for-purpose. Extraction and LC-tandem MS methods were developed to accurately certify the concentrations of OA, DTX1, and DTX2 using a combination of standard addition and matrix-matched calibration to compensate for matrix effects in electrospray ionization. The concentration of domoic acid was also certified. Uncertainties were assigned following standards and guidelines from the International Organization for Standardization. The presence of other toxins in the CRM was also assessed and information values are reported for OA and DTX acyl esters.

A New Application of Continuous Wavelet Transform to Overlapping Chromatograms for the Quantitative Analysis of Amiloride Hydrochloride and Hydrochlorothiazide in Tablets by Ultra-Performance Liquid Chromatography

2012 ◽  
Vol 95 (3) ◽  
pp. 751-756 ◽  
Author(s):  
Erdal Dinç ◽  
Eda Büker
Keyword(s):  
Signal Processing ◽  
Wavelet Transform ◽  
Quantitative Analysis ◽  
Continuous Wavelet Transform ◽  
Standard Addition ◽  
Ultra Performance Liquid Chromatography ◽  
Continuous Wavelet ◽  
Constant Flow Rate ◽  
Acquity Uplc ◽  
Amiloride Hydrochloride

Abstract A new application of continuous wavelet transform (CWT) to overlapping peaks in a chromatogram was developed for the quantitative analysis of amiloride hydrochloride (AML) and hydrochlorothiazide (HCT) in tablets. Chromatographic analysis was done by using an ACQUITY ultra-performance LC (UPLC) BEH C18 column (50 × 2.1 mm id, 1.7 μm particle size) and a mobile phase consisting of methanol–0.1 M acetic acid (21 + 79, v/v) at a constant flow rate of 0.3 mL/min with diode array detection at 274 nm. The overlapping chromatographic peaks of the calibration set consisting of AML and HCT mixtures were recorded rapidly by using an ACQUITY UPLC H-Class system. The overlapping UPLC data vectors of AML and HCT drugs and their samples were processed by CWT signal processing methods. The calibration graphs for AML and HCT were computed from the relationship between concentration and areas of chromatographic CWT peaks. The applicability and validity of the improved UPLC-CWT approaches were confirmed by recovery studies and the standard addition technique. The proposed UPLC-CWT methods were applied to the determination of AML and HCT in tablets. The experimental results indicated that the suggested UPLC-CWT signal processing provides accurate and precise results for industrial QC and quantitative evaluation of AML-HCT tablets.

scholarly journals Development, characterization and first deployment of an improved online reactive oxygen species analyzer

2018 ◽  
Vol 11 (1) ◽  
pp. 65-80 ◽  
Author(s):  
Jun Zhou ◽  
Emily A. Bruns ◽  
Peter Zotter ◽  
Giulia Stefenelli ◽  
André S. H. Prévôt ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Detection Limit ◽  
Atmospheric Aerosols ◽  
Half Life ◽  
Matrix Effects ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Wood Combustion ◽  
Storage Duration ◽  
High Concentrations

Abstract. Inhalation of atmospheric particles is linked to human diseases. Reactive oxygen species (ROS) present in these atmospheric aerosols may play an important role. However, the ROS content in aerosols and their formation pathways are still largely unknown. Here, we have developed an online and offline ROS analyzer using a 2′,7′-dichlorofluorescin (DCFH) based assay. The ROS analyzer was calibrated with H2O2 and its sensitivity was characterized using a suite of model organic compounds. The instrument detection limit determined as 3 times the noise is 1.3 nmol L−1 for offline analysis and 2 nmol m−3 of sampled air when the instrument is operated online at a fluorescence response time of approximately 8 min, while the offline method detection limit is 18 nmol L−1. Potential interferences from gas-phase O3 and NO2 as well as matrix effects of particulate SO42− and NO3− were tested, but not observed. Fe3+ had no influence on the ROS signal, while soluble Fe2+ reduced it if present at high concentrations in the extracts. Both online and offline methods were applied to identify the ROS content of different aerosol types, i.e., ambient aerosols as well as fresh and aged aerosols from wood combustion emissions. The stability of the ROS was assessed by comparing the ROS concentration measured by the same instrumentation online in situ with offline measurements. We also analyzed the evolution of ROS in specific samples by conducting the analysis after storage times of up to 4 months. The ROS were observed to decay with increasing storage duration. From their decay behavior, ROS in secondary organic aerosol (SOA) can be separated into short- and long-lived fractions. The half-life of the short-lived fraction was 1.7 ± 0.4 h, while the half-life of the long-lived fraction could not be determined with our uncertainties. All these measurements showed consistently that on average 60 ± 20 % of the ROS were very reactive and disappeared during the filter storage time. This demonstrates the importance of a fast online measurement of ROS.

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