Time since last drink is positively associated with heart rate variability in outpatients with alcohol use disorder: Further evidence of psychophysiological recovery in early alcohol use disorder recovery.

Heart rate variability (HRV) is a biomarker of psychological and physiological health with greater variability reflecting greater psychophysiological regulatory capacity. The damaging effects of chronic, heavy alcohol use on HRV have been well explored, with greater alcohol use associated with lower resting HRV. In this study we sought to replicate and extend our previous finding that HRV improves as individuals with alcohol use disorder (AUD) reduce or stop drinking and engage in treatment. With a sample of treatment engaged adults in the first year of a current AUD recovery attempt ( N = 42), we used general linear models were used to explore associations between indices of HRV (dependent variables) and time since last alcoholic drink at study baseline assessed using timeline follow-back (independent variable), with checks for effects of age, medication, and baseline AUD severity. As predicted, HRV increased as a function of time since last drink, however, contrary to hypotheses, HR did not decrease. Effect sizes were largest for HRV indices fully under parasympathetic control, and these significant associations remained after controlling for age, medications, and AUD severity. Because HRV is an indicant of psychophysiological health, as well as self-regulatory capacity that may portend subsequent relapse risk, assessing HRV in individuals entering AUD treatment could provide important information about patient risk. At-risk patients may do well with additional support and may especially benefit from interventions like Heart Rate Variability Biofeedback that exercise the psychophysiological systems regulating brain/cardiovascular communication.

Time Since Last Drink is Positively Associated with Heart Rate Variability in Outpatients with Alcohol Use Disorder: Further Evidence of Psychophysiological Recovery in Early Alcohol Use Disorder Recovery.

Heart rate variability (HRV) is a biomarker of psychological and physiological health with greater variability reflecting greater psychophysiological regulatory capacity. The damaging effects of chronic, heavy alcohol use on HRV have been well explored, with greater alcohol use associated with lower resting HRV. In this study we sought to replicate and extend our previous finding that HRV improves as individuals with alcohol use disorder (AUD) reduce or stop drinking and engage in treatment. With a sample of treatment engaged adults in the first year of a current AUD recovery attempt (N = 42), we used general linear models to explore associations between indices of HRV (dependent variables) and time since last alcoholic drink at study baseline assessed using timeline follow-back (independent variable), with checks for effects of age, medication, and baseline AUD severity. As predicted, HRV increased as a function of time since last drink, however, contrary to hypotheses, HR did not decrease. Effect sizes were largest for HRV indices fully under parasympathetic control, and these significant associations remained after controlling for age, medications, and AUD severity. Because HRV is an indicant of psychophysiological health, as well as self-regulatory capacity that may portend subsequent relapse risk, assessing HRV in individuals entering AUD treatment could provide important information about patient risk. At-risk patients may do well with additional support and may especially benefit from interventions like Heart Rate Variability Biofeedback that exercise the psychophysiological systems regulating brain/cardiovascular communication.

Feasibility of a Selective Epoxidation Technique for Use in Quantification of Peracetic Acid in Air Samples Collected on Sorbent Tubes.

Peracetic acid is a disinfection agent used in medical and food processing facilities, and occupational exposures have been documented. To facilitate characterization of daily occupational exposures, the current work describes the development of a personal sampling technique to quantify the peracetic acid concentration in air samples. Peracetic acid atmospheres were generated in 100 L Teflon chambers, and samples were collected on 350 mg XAD-7 solid sorbent tubes for 4 h at a flow rate of 250 mL/min using a personal sampling pump. Indirect measurement of peracetic acid was achieved by desorption from the sorbent and subsequent treatment with cyclohexene to initiate an epoxidation reaction, formally known as the Prilezhaev reaction. The epoxidation product, cyclohexene oxide, was quantified by gas chromatography-mass spectrometry. The reaction enabled quantification of peracetic acid with high specificity over the common co-contaminants hydrogen peroxide and acetic acid, which were introduced in 10-fold and 100-fold excess to challenge the reaction. The technique also demonstrated an overall estimate of bias and precision of 11 and 8%, respectively, and a limit of detection of 60 ppbv was estimated. Preliminary storage experiments indicate that unreacted peracetic acid is stable on the sorbent tubes for 72 h when stored at -20 °C following collection. Overall, the specificity of the reaction and capability to sample for longer time periods than current methods, in addition to the use of safer personal sampling materials, demonstrate the utility of this technique for peracetic acid measurement in air.

Mass SARS-CoV-2 Testing in a Dormitory-Style Correctional Facility in Arkansas.

Objectives. To assess SARS-CoV-2 transmission within a correctional facility and recommend mitigation strategies.Methods. From April 29 to May 15, 2020, we established the point prevalence of COVID-19 among incarcerated persons and staff within a correctional facility in Arkansas. Participants provided respiratory specimens for SARS-CoV-2 testing and completed questionnaires on symptoms and factors associated with transmission.Results. Of 1647 incarcerated persons and 128 staff tested, 30.5% of incarcerated persons (range by housing unit = 0.0%-58.2%) and 2.3% of staff tested positive for SARS-CoV-2. Among those who tested positive and responded to symptom questions (431 incarcerated persons, 3 staff), 81.2% and 33.3% were asymptomatic, respectively. Most incarcerated persons (58.0%) reported wearing cloth face coverings 8 hours or less per day, and 63.3% reported close contact with someone other than their bunkmate.Conclusions. If testing remained limited to symptomatic individuals, fewer cases would have been detected or detection would have been delayed, allowing transmission to continue. Rapid implementation of mass testing and strict enforcement of infection prevention and control measures may be needed to mitigate spread of SARS-CoV-2 in this setting.

Large-Format Additive Manufacturing and Machining Using High-Melt-Temperature Polymers. Part I: Real-Time Particulate and Gas-Phase Emissions.

The literature on emissions during material extrusion additive manufacturing with 3-D printers is expanding; however, there is a paucity of data for large-format additive manufacturing (LFAM) machines that can extrude high-melt-temperature polymers. Emissions from two LFAM machines were monitored during extrusion of six polymers: acrylonitrile butadiene styrene (ABS), polycarbonate (PC), high-melt-temperature polysulfone (PSU), poly(ether sulfone) (PESU), polyphenylene sulfide (PPS), and Ultem (poly(ether imide)). Particle number, total volatile organic compound (TVOC), carbon monoxide (CO), and carbon dioxide (CO2) concentrations were monitored in real-time. Particle emission rate values (no./min) were as follows: ABS (1.7 × 1011 to 7.7 × 1013), PC (5.2 × 1011 to 3.6 × 1013), Ultem (5.7 × 1012 to 3.1 × 1013), PPS (4.6 × 1011 to 6.2 × 1012), PSU (1.5 × 1012 to 3.4 × 1013), and PESU (2.0 to 5.0 × 1013). For print jobs where the mass of extruded polymer was known, particle yield values (g-1 extruded) were as follows: ABS (4.5 × 108 to 2.9 × 1011), PC (1.0 × 109 to 1.7 × 1011), PSU (5.1 × 109 to 1.2 × 1011), and PESU (0.8 × 1011 to 1.7 × 1011). TVOC emission yields ranged from 0.005 mg/g extruded (PESU) to 0.7 mg/g extruded (ABS). The use of wall-mounted exhaust ventilation fans was insufficient to completely remove airborne particulate and TVOC from the print room. Real-time CO monitoring was not a useful marker of particulate and TVOC emission profiles for Ultem, PPS, or PSU. Average CO2 and particle concentrations were moderately correlated (r s = 0.76) for PC polymer. Extrusion of ABS, PC, and four high-melt-temperature polymers by LFAM machines released particulate and TVOC at levels that could warrant consideration of engineering controls. LFAM particle emission yields for some polymers were similar to those of common desktop-scale 3-D printers.

Large-Format Additive Manufacturing and Machining Using High-Melt-Temperature Polymers. Part II: Characterization of Particles and Gases.

Extrusion of high-melt-temperature polymers on large-format additive manufacturing (LFAM) machines releases particles and gases, though there is no data describing their physical and chemical characteristics. Emissions from two LFAM machines were monitored during extrusion of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) polymers as well as high-melt-temperature Ultem (poly(ether imide)), polysulfone (PSU), poly(ether sulfone) (PESU), and polyphenylene sulfide (PPS) polymers. Filter samples of particles were collected for quantification of elements and bisphenol A and S (BPA, BPS) and visualization of morphology. Individual gases were quantified on substance-specific media. Aerosol sampling demonstrated that concentrations of elements were generally low for all polymers, with a maximum of 1.6 mg/m3 for iron during extrusion of Ultem. BPA, an endocrine disruptor, was released into air during extrusion of PC (range: 0.4 ± 0.1 to 21.3 ± 5.3 µg/m3). BPA and BPS (also an endocrine disruptor) were released into air during extrusion of PESU (BPA, 2.0-8.7 µg/m3; BPS, 0.03-0.07 µg/m3). Work surfaces and printed parts were contaminated with BPA (<8-587 ng/100 cm2) and BPS (<0.22-2.5 ng/100 cm2). Gas-phase sampling quantified low levels of respiratory irritants (phenol, SO2, toluene, xylenes), possible or known asthmagens (caprolactam, methyl methacrylate, 4-oxopentanal, styrene), and possible occupational carcinogens (benzene, formaldehyde, acetaldehyde) in air. Characteristics of particles and gases released by high-melt-temperature polymers during LFAM varied, which indicated the need for polymer-specific exposure and risk assessments. The presence of BPA and BPS on surfaces revealed a previously unrecognized source of dermal exposure for additive manufacturing workers using PC and PESU polymers.

Chemical Emissions From Heated Vitamin E Acetate-Insights to Respiratory Risks From Electronic Cigarette Liquid Oil Diluents Used in the Aerosolization of Δ9-THC-Containing Products.

As of February 18, 2020, the e-cigarette, or vaping, product use associated lung injury (EVALI) outbreak caused the hospitalization of a total of 2,807 patients and claimed 68 lives in the United States. Though investigations have reported a strong association with vitamin E acetate (VEA), evidence from reported EVALI cases is not sufficient to rule out the contribution of other chemicals of concern, including chemicals in either THC or non-THC products. This study characterized chemicals evolved when diluent oils were heated to temperatures that mimic e-cigarette, or vaping, products (EVPs) to investigate production of potentially toxic chemicals that might have caused lung injury. VEA, vitamin E, coconut, and medium chain triglyceride (MCT) oil were each diluted with ethanol and then tested for constituents and impurities using a gas chromatograph mass spectrometer (GC/MS). Undiluted oils were heated at 25°C (control), 150°C, and 250°C in an inert chamber to mimic a range of temperatures indicative of aerosolization from EVPs. Volatilized chemicals were collected using thermal desorption tubes, analyzed using a GC/MS, and identified. Presence of identified chemicals was confirmed using retention time and ion spectra matching with analytic standards. Direct analysis of oils, as received, revealed that VEA and vitamin E were the main constituents of their oils, and coconut and MCT oils were nearly identical having two main constituents: glycerol tricaprylate and 2-(decanoyloxy) propane-1,3-diyl dioctanoate. More chemicals were measured and with greater intensities when diluent oils were heated at 250°C compared to 150°C and 25°C. Vitamin E and coconut/MCT oils produced different chemical emissions. The presence of some identified chemicals is of potential health consequence because many are known respiratory irritants and acute respiratory toxins. Exposure to a mixture of hazardous chemicals may be relevant to the development or exacerbation of EVALI, especially when in concert with physical damage caused by lung deposition of aerosols produced by aerosolizing diluent oils.

Baseline Performance of Real-World Clinical Practice Within a Statewide Emergency Medicine Quality Network: The Michigan Emergency Department Improvement Collaborative (MEDIC).

STUDY OBJECTIVE: Large-scale quality and performance measurement across unaffiliated hospitals is an important strategy to drive practice change. The Michigan Emergency Department Improvement Collaborative (MEDIC), established in 2015, has baseline performance data to identify practice variation across 15 diverse emergency departments (EDs) on key emergency care quality indicators. METHODS: MEDIC is a unique physician-led partnership supported by a major third-party payer. Member sites contribute electronic health record data and trained abstractors add supplementary data for eligible cases. Quality measures include computed tomography (CT) appropriateness for minor head injury, using the Canadian CT Head Rule for adults and Pediatric Emergency Care Applied Network rules for children; chest radiograph use for children with asthma, bronchiolitis, and croup; and diagnostic yield of CTs for suspected pulmonary embolism. Baseline performance was established with statistical process control charts. RESULTS: From June 1, 2016, to October 31, 2017, the MEDIC registry contained 1,124,227 ED visits, 23.2% for children (<18 years). Overall baseline performance included the following: 40.9% of adult patients with minor head injury (N=11,857) had appropriate CTs (site range 24.3% to 58.6%), 10.3% of pediatric minor head injury cases (N=11,183) exhibited CT overuse (range 5.8% to 16.8%), 38.1% of pediatric patients with a respiratory condition (N=18,190) received a chest radiograph (range 9.0% to 62.1%), and 8.7% of pulmonary embolism CT results (N=16,205) were positive (range 7.5% to 14.3%). CONCLUSION: Performance varied greatly, with demonstrated opportunity for improvement. MEDIC provides a robust platform for emergency physician engagement across ED practice settings to improve care and is a model for other states.

Are Rural and Urban Emergency Departments Equally Prepared to Reduce Avoidable Hospitalizations?

INTRODUCTION: Attempts to reduce low-value hospital care often focus on emergency department (ED) hospitalizations. We compared rural and urban EDs in Michigan on resources designed to reduce avoidable admissions. METHODS: A cross-sectional, web-based survey was emailed to medical directors and/or nurse managers of the 135 hospital-based EDs in Michigan. Questions included presence of clinical pathways, services to reduce admissions, and barriers to connecting patients to outpatient services. We performed chi-squared comparisons, regression modeling, and predictive margins. RESULTS: Of 135 EDs, 64 (47%) responded with 33 in urban and 31 in rural counties. Clinical pathways were equally present in urban and rural EDs (67% vs 74%, p=0.5). Compared with urban EDs, rural EDs reported greater access to extended care facilities (21% vs 52%, p=0.02) but less access to observation units (52% vs 35%, p=0.04). Common barriers to connecting ED patients to outpatient services exist in both settings, including lack of social support (88% and 76%, p=0.20), and patient/family preference (68% and 68%, p=1.0). However, rural EDs were more likely to report time required for care coordination (88% vs 66%, p=0.05) and less likely to report limitations to home care (21% vs 48%, p=0.05) as barriers. In regression modeling, ED volume was predictive of the presence of clinical pathways rather than rurality. CONCLUSION: While rural-urban differences in resources and barriers exist, ED size rather than rurality may be a more important indicator of ability to reduce avoidable hospitalizations.

Undeclared formaldehyde levels in patient consumer products: formaldehyde test kit utility.

PURPOSE: Formaldehyde allergic contact dermatitis (ACD) may be due to products with free formaldehyde or formaldehyde-releasing agents; however, assessment of formaldehyde levels in such products is infrequently conducted. The present study quantifies total releasable formaldehyde from "in-use" products associated with formaldehyde ACD and tests the utility of commercially available formaldehyde spot test kits. MATERIALS AND METHODS: Personal care products from 2 patients with ACD to formaldehyde were initially screened at the clinic for formaldehyde using a formaldehyde spot test kit. Formaldehyde positive products were sent to the laboratory for confirmation by gas chromatography-mass spectrometry. In addition, 4 formaldehyde spot test kits were evaluated for potential utility in a clinical setting. RESULTS: Nine of the 10 formaldehyde spot test kit positive products obtained from formaldehyde allergic patients had formaldehyde with total releasable formaldehyde levels ranging from 5.4 to 269.4 µg/g. Of these, only two shampoos tested listed a formaldehyde-releasing agent in the ingredients or product literature. Subsequently, commercially available formaldehyde spot test kits were evaluated in the laboratory for ability to identify formaldehyde in personal care products. CONCLUSIONS: Chemical based formaldehyde spot test were more reliable than the enzymatic based test in identifying product releasable formaldehyde content. It is concluded that product labeled ingredient lists and available information are often inadequate to confirm the potential for formaldehyde exposure and chemical based spot test kits may have utility for identification of potential formaldehyde exposure from personal care products.

Michigan Emergency Department Leader Attitudes Toward and Experiences With Clinical Pathways to Guide Admission Decisions: A Mixed-methods Study.

OBJECTIVES: The objective was to characterize emergency department (ED) leader's attitudes toward potentially avoidable admissions and experiences with the use of clinical pathways to guide admission decisions, including the challenges and successes with implementation of these pathways. METHODS: A mixed-methods study of Michigan ED leaders was conducted. First, a cross-sectional Web-based survey was distributed via e-mail to all 135 hospital-based EDs in the state. Descriptive statistics were calculated. Survey participants who provided contact information were considered eligible for follow-up. Semistructured interviews were conducted by telephone until thematic saturation was reached. Interviews were recorded, transcribed verbatim, reviewed for accuracy, and thematically coded. Representative quotes were extracted for reporting. RESULTS: Survey responses were received from 64 ED leaders (48% eligible response rate). Semistructured interviews were conducted with a purposeful sample of 11 of the 29 representatives willing to be contacted. Eight sites implemented clinical care pathways as a strategy to reduce avoidable admissions. Pathways were developed for high-frequency conditions. Many pathways were multidisciplinary, incorporating case managers and outpatient care providers, which was thought to improve acceptability. Five models of care emerged 1) standardized care, 2) observation medicine, 3) enhanced follow-up, 4) care coordination, and 5) comprehensive programs. We identified barriers to and facilitators of discharging a patient from the ED when an admission otherwise could be avoided. Barriers included limited access to follow-up, lack of care coordination, and lack of trust in patient's ability to provide self-care or navigate the system. Facilitators included strong relationships with outpatient providers, care coordination, and shared decision making. CONCLUSIONS: Potential solutions to help avoid hospitalization from the ED include multidisciplinary clinical care pathways. Successful pathways emerged from bringing stakeholders from the ED, hospital, and health care community together. Additionally, emergency providers need systems and supports in place to help their patients navigate follow-up care in a timely fashion.

Three-dimensional printing with nano-enabled filaments releases polymer particles containing carbon nanotubes into air.

Fused deposition modeling (FDM™) 3-dimensional printing uses polymer filament to build objects. Some polymer filaments are formulated with additives, though it is unknown if they are released during printing. Three commercially available filaments that contained carbon nanotubes (CNTs) were printed with a desktop FDM™ 3-D printer in a chamber while monitoring total particle number concentration and size distribution. Airborne particles were collected on filters and analyzed using electron microscopy. Carbonyl compounds were identified by mass spectrometry. The elemental carbon content of the bulk CNT-containing filaments was 1.5 to 5.2 wt%. CNT-containing filaments released up to 1010 ultrafine (d < 100 nm) particles/g printed and 106 to 108 respirable (d ~0.5 to 2 µm) particles/g printed. From microscopy, 1% of the emitted respirable polymer particles contained visible CNTs. Carbonyl emissions were observed above the limit of detection (LOD) but were below the limit of quantitation (LOQ). Modeling indicated that, for all filaments, the average proportional lung deposition of CNT-containing polymer particles was 6.5%, 5.7%, and 7.2% for the head airways, tracheobronchiolar, and pulmonary regions, respectively. If CNT-containing polymer particles are hazardous, it would be prudent to control emissions during use of these filaments.

Identification and quantification of carbonyl-containing α-pinene ozonolysis products using O-tert-butylhydroxylamine hydrochloride.

The yields of carbonyl-containing reaction products from the ozonolysis of α-pinene have been investigated using concentrations of ozone found in the indoor environment ([O3] ≤ 100 ppb). An impinger was used to collect gas-phase oxidation products in water, where the derivatization agent O-tert-butylhydroxylamine hydrochloride (TBOX) and gas chromatography-mass spectrometry were used to identify carbonyl-containing species. Seven carbonyl-containing products were observed. The yield of the primary product, pinonaldehyde was measured to be 76 %. Using cyclohexane as a hydroxyl radical (OH) scavenger, the yield of pinonaldehyde decreased to 46 %, indicating the influence secondary OH radicals have on α-pinene ozonolysis products. Furthermore, the use of TBOX, a small molecular weight derivatization agent, allowed for the acquisition of the first mass spectral data of oxopinonaldehyde, a tricarbonyl reaction product of α-pinene ozonolysis. The techniques described herein allow for an effective method for the collection and identification of terpene oxidation products in the indoor environment.

Care of Acute Gastrointestinal Conditions in the Observation Unit.

The Emergency Department Observation Unit (EDOU) provides a viable alternative to inpatient admission for the management of many acute gastrointestinal conditions with additional opportunities of reducing resource utilization and reducing radiation exposure. Using available evidence-based criteria to determine appropriate patient selection, evaluation, and treatment provides higher-quality medical care and improved patient satisfaction. Discussions of factors involved in creating an EDOU capable of caring for acute gastrointestinal conditions and clinical protocol examples of acute appendicitis, gastrointestinal hemorrhage, and acute pancreatitis provide a framework from which a successful EDOU can be built.

Characterization of chemical contaminants generated by a desktop fused deposition modeling 3-dimensional Printer.

Printing devices are known to emit chemicals into the indoor atmosphere. Understanding factors that influence release of chemical contaminants from printers is necessary to develop effective exposure assessment and control strategies. In this study, a desktop fused deposition modeling (FDM) 3-dimensional (3-D) printer using acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) filaments and two monochrome laser printers were evaluated in a 0.5 m3 chamber. During printing, chamber air was monitored for vapors using a real-time photoionization detector (results expressed as isobutylene equivalents) to measure total volatile organic compound (TVOC) concentrations, evacuated canisters to identify specific VOCs by off-line gas chromatography-mass spectrometry (GC-MS) analysis, and liquid bubblers to identify carbonyl compounds by GC-MS. Airborne particles were collected on filters for off-line analysis using scanning electron microscopy with an energy dispersive x-ray detector to identify elemental constituents. For 3-D printing, TVOC emission rates were influenced by a printer malfunction, filament type, and to a lesser extent, by filament color; however, rates were not influenced by the number of printer nozzles used or the manufacturer's provided cover. TVOC emission rates were significantly lower for the 3-D printer (49-3552 µg h-1) compared to the laser printers (5782-7735 µg h-1). A total of 14 VOCs were identified during 3-D printing that were not present during laser printing. 3-D printed objects continued to off-gas styrene, indicating potential for continued exposure after the print job is completed. Carbonyl reaction products were likely formed from emissions of the 3-D printer, including 4-oxopentanal. Ultrafine particles generated by the 3-D printer using ABS and a laser printer contained chromium. Consideration of the factors that influenced the release of chemical contaminants (including known and suspected asthmagens such as styrene and 4-oxopentanal) from a FDM 3-D printer should be made when designing exposure assessment and control strategies.

A chamber study of alkyl nitrate production formed by terpene ozonolysis in the presence of NO and alkanes.

Organic nitrates are relatively long-lived species and have been shown to have a potential impact on atmospheric chemistry on local, regional, and even global scales. However, the significance of these compounds in the indoor environment remains to be seen. This work describes an impinger-based sampling and analysis technique for organic nitrate species, focusing on formation via terpene ozonolysis in the presence of nitric oxide (NO). Experiments were conducted in a Teflon film environmental chamber to measure the formation of alkyl nitrates produced from α-pinene ozonolysis in the presence of NO and alkanes using gas chromatography with an electron capture detector. For the different concentrations of NO and O3 analyzed, the concentration ratio of [O3]/[NO] around 1 was found to produce the highest organic nitrate concentration, with [O3] = 100 ppb & [NO] = 105 ppb resulting in the most organic nitrate formation, roughly 5 ppb. The experiments on α-pinene ozonolysis in the presence of NO suggest that organic nitrates have the potential to form in indoor air between infiltrated ozone/NO and terpenes from household and consumer products.

Limonene ozonolysis in the presence of nitric oxide: Gas-phase reaction products and yields.

The reaction products from limonene ozonolysis were investigated using the new carbonyl derivatization agent, O-tert-butylhydroxylamine hydrochloride (TBOX). With ozone (O3) as the limiting reagent, five carbonyl compounds were detected. The yields of the carbonyl compounds are discussed with and without the presence of a hydroxyl radical (OH•) scavenger, giving insight into the influence secondary OH radicals have on limonene ozonolysis products. The observed reaction product yields for limonaketone (LimaKet), 7-hydroxyl-6-oxo-3-(prop-1-en-2-yl)heptanal (7H6O), and 2-acetyl-5-oxohexanal (2A5O) were unchanged suggesting OH• generated by the limonene + O3 reaction does not contribute to their formation. The molar yields of 3-isopropenyl-6-oxo-heptanal (IPOH) and 3-acetyl-6-oxoheptanal (3A6O) decreased by 68% and >95%; respectively, when OH• was removed. This suggests that OH• radicals significantly impact the formation of these products. Nitric oxide (NO) did not significantly affect the molar yields of limonaketone or IPOH. However, NO (20 ppb) considerably decreased the molar reaction product yields of 7H6O (62%), 2A5O (63%), and 3A6O (47%), suggesting NO reacted with peroxyl intermediates, generated during limonene ozonolysis, to form other carbonyls (not detected) or organic nitrates. These studies give insight into the transformation of limonene and its reaction products that can lead to indoor exposures.

Gas-phase reaction products and yields of terpinolene with ozone and nitric oxide using a new derivatization agent.

The new derivatization agent, O-tert-butylhydroxylamine hydrochloride (TBOX) was used to investigate the carbonyl reaction products from terpinolene ozonolysis. With ozone (O3) as the limiting reagent, four carbonyl compounds were detected: methylglyoxal (MG), 4-methylcyclohex-3-en-1-one, (4MCH), 6-oxo-3-(propan-2-ylidene) heptanal (6OPH), and 3,6-dioxoheptanal (36DOH). The tricarbonyl 36DOH has not been previously observed. Using cyclohexane as a hydroxyl radical (OH•) scavenger, the yields of 6OPH and 36DOH were reduced indicating the influence secondary OH• radicals have on terpinolene ozonolysis products. However, the MG yield increased and the 4MCH yield was unchanged when OH•radicals were scavenged suggesting they are only made by the terpinolene + O3 reaction. The detection of 36DOH using TBOX highlights the advantages of a smaller molecular weight derivatization agent for the detection of multi-carbonyl compounds. The product yields from terpinolene ozonolysis experiments conducted in the presence of 20 ppb nitric oxide (NO) remained unchanged except for MG which decreased. However, in experiments where O3 was kept constant at 50 ppb and NO was varied (20, 50, 100 ppb) MG, 6OPH, 36DOH decreased with increasing NO while 4MCH increased with increasing NO. The use of TBOX derivatization if combined with other derivatization agents may address a recurring need to simply and accurately detect multi-functional oxygenated species in air.

A new agent for derivatizing carbonyl species used to investigate limonene ozonolysis.

A new method for derivatizing carbonyl compounds is presented. The conversion of a series of dicarbonyls to oximes in aqueous solution and from gas-phase sampling was achieved using O-tert-butyl-hydroxylamine hydrochloride (TBOX). Some advantages of using this derivatization agent include: aqueous reactions, lower molecular weight oximes, and shortened oxime-formation reaction time. Additionally, the TBOX derivatization technique was used to investigate the carbonyl reaction products from limonene ozonolysis. With ozone (O3) as the limiting reagent, four carbonyl compounds were detected: 7-hydroxy-6-oxo-3-(prop-1-en-2-yl)heptanal; 3-Isopropenyl-6-oxoheptanal (IPOH), 3-acetyl-6-oxoheptanal (3A6O) and one carbonyl of unknown structure. Using cyclohexane as a hydroxyl (OH•) radical scavenger, the relative yields (peak area) of the unknown carbonyl, IPOH, and 3A6O were reduced indicating the influence secondary OH radicals have on limonene ozonolysis products. The relative yield of the hydroxy-dicarbonyl based on the chromatogram was unchanged suggesting it is only made by the limonene + O3 reaction. The detection of 3A6O using TBOX highlights the advantages of a smaller molecular weight derivatization agent for the detection of multi-carbonyl compounds. The use of TBOX derivatization if combined with other derivatization agents may address a recurring need to simply and accurately detect multi-functional oxygenated species in air.

Cavity ring-down spectroscopy with an automated control feedback system for investigating nitrate radical surface chemistry reactions.

Nitrate radical (NO(3)(●)) surface chemistry of indoor environments has not been well studied due to the difficulty in generating and maintaining NO(3)(●) at low concentrations for long term exposures. This article presents the Surface Chemistry Reactant Air Delivery and Experiment System (SCRADES), a novel feedback controlled system developed to deliver nitrate radicals at specified concentrations (50-500 ppt, ±30 ppt) and flow rates (500-2000 ml min(-1)) to a variety of indoor surfaces to initiate reaction chemistry for periods of up to 72 h. The system uses a cavity ring-down spectrometer (CRDS), with a detection limit of 1.7 ppt, to measure the concentration of NO(3)(●) supplied to a 24 l experiment chamber. Nitrate radicals are introduced via thermal decomposition of N(2)O(5) and diluted with clean dry air until the desired concentration is achieved. Additionally, this article addresses details concerning NO(3)(●) loss through the system, consistency of the NO(3)(●) concentration delivered, and stability of the CRDS cavity over long exposure durations (72 h).