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1.
Am J Perinatol ; 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38889888

RESUMO

OBJECTIVE: The transition from the neonatal intensive care unit (NICU) to the home is complex and multifaceted for families and infants, particularly those with ongoing medical needs. Our hospital utilizes a remote monitoring program called Growing @ Home (G@H) to support discharge from the NICU with continued nasogastric tube (NGT) feeds. We aim to describe the experience of the transition from NICU to home for families enrolled in G@H. STUDY DESIGN: Using a semistructured interviewing technique, parents of infants discharged on G@H were interviewed at NICU discharge, at 1 month, and at 6 months after NICU discharge. Interviews were recorded and transcribed into data analysis software. Conventional content analysis was used to analyze qualitative data. Codes were assigned to describe key elements of the interviews and used to identify major themes. RESULTS: Parents (n = 17) identified three major themes when discussing the effect of G@H on the transition to home. The program provided a means of escape from the NICU, allowing families to stop living split lives between their homes and the NICU. It acted as a middle ground between the restrictive yet supportive NICU environment, and the normal yet isolated home environment. G@H served as a safety net for families, providing a continued connection to the NICU for their still-fragile infants. CONCLUSION: G@H utilizes telehealth to positively support the complex transition from NICU to home for families and infants discharged with NGT feeds. KEY POINTS: · G@H program supported parents in their transition from NICU to home.. · G@H program provided a means of escape from the NICU.. · G@H program was a middle ground between the NICU and home.. · G@H program created a safety net after discharge.. · Follow-up with a consistent provider was essential to a positive parent experience..

2.
JAMA Netw Open ; 7(5): e2411140, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38758557

RESUMO

Importance: Providing assisted ventilation during delayed umbilical cord clamping may improve outcomes for extremely preterm infants. Objective: To determine whether assisted ventilation in extremely preterm infants (23 0/7 to 28 6/7 weeks' gestational age [GA]) followed by cord clamping reduces intraventricular hemorrhage (IVH) or early death. Design, Setting, and Participants: This phase 3, 1:1, parallel-stratified randomized clinical trial conducted at 12 perinatal centers across the US and Canada from September 2, 2016, through February 21, 2023, assessed IVH and early death outcomes of extremely preterm infants randomized to receive 120 seconds of assisted ventilation followed by cord clamping vs delayed cord clamping for 30 to 60 seconds with ventilatory assistance afterward. Two analysis cohorts, not breathing well and breathing well, were specified a priori based on assessment of breathing 30 seconds after birth. Intervention: After birth, all infants received stimulation and suctioning if needed. From 30 to 120 seconds, infants randomized to the intervention received continuous positive airway pressure if breathing well or positive-pressure ventilation if not, with cord clamping at 120 seconds. Control infants received 30 to 60 seconds of delayed cord clamping followed by standard resuscitation. Main Outcomes and Measures: The primary outcome was any grade IVH on head ultrasonography or death before day 7. Interpretation by site radiologists was confirmed by independent radiologists, all masked to study group. To estimate the association between study group and outcome, data were analyzed using the stratified Cochran-Mantel-Haenszel test for relative risk (RR), with associations summarized by point estimates and 95% CIs. Results: Of 1110 women who consented to participate, 548 were randomized and delivered infants at GA less than 29 weeks. A total of 570 eligible infants were enrolled (median [IQR] GA, 26.6 [24.9-27.7] weeks; 297 male [52.1%]). Intraventricular hemorrhage or death occurred in 34.9% (97 of 278) of infants in the intervention group and 32.5% (95 of 292) in the control group (adjusted RR, 1.02; 95% CI, 0.81-1.27). In the prespecified not-breathing-well cohort (47.5% [271 of 570]; median [IQR] GA, 26.0 [24.7-27.4] weeks; 152 male [56.1%]), IVH or death occurred in 38.7% (58 of 150) of infants in the intervention group and 43.0% (52 of 121) in the control group (RR, 0.91; 95% CI, 0.68-1.21). There was no evidence of differences in death, severe brain injury, or major morbidities between the intervention and control groups in either breathing cohort. Conclusions and Relevance: This study did not show that providing assisted ventilation before cord clamping in extremely preterm infants reduces IVH or early death. Additional study around the feasibility, safety, and efficacy of assisted ventilation before cord clamping may provide additional insight. Trial Registration: ClinicalTrials.gov Identifier: NCT02742454.


Assuntos
Lactente Extremamente Prematuro , Clampeamento do Cordão Umbilical , Humanos , Recém-Nascido , Feminino , Masculino , Clampeamento do Cordão Umbilical/métodos , Canadá , Respiração Artificial/métodos , Hemorragia Cerebral Intraventricular/prevenção & controle , Cordão Umbilical , Pressão Positiva Contínua nas Vias Aéreas/métodos , Idade Gestacional , Fatores de Tempo , Estados Unidos
3.
J Insect Sci ; 24(2)2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38554055

RESUMO

Winter climate change constitutes not only a shift in chronic conditions (i.e., shorter length and warmer average temperatures) but will also influence the dynamics of extreme warming events. The latter may be particularly important for the performance and survival of insects, given their susceptibility to temperature variation. However, metabolic sensitivity changes over the course of winter diapause, and thus, insect responses to warming may vary depending on when the event occurs. To determine the influence of warm-up timing, we exposed the spruce budworm, Choristoneura fumiferana ((Clem.), Lepidoptera: Tortricidae), to acute warming events in early-, mid-, and late-dormancy and measured impacts on survival, performance, and biochemistry. While we did not observe any impacts of warm-up timing on performance, survival to the adult stage was significantly reduced in response to earlier warming. Additionally, glycogen concentration was significantly higher in response to early and late warming exposure. Collectively, these results suggest that the timing of extreme winter warming events matters, with consequences for both lethal and sublethal responses.


Assuntos
Diapausa , Mariposas , Picea , Animais , Estações do Ano , Temperatura
5.
J Perinatol ; 43(9): 1125-1130, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37468613

RESUMO

OBJECTIVE: Our neonatal intensive care unit utilizes remote patient monitoring to facilitate hospital discharge with nasogastric tube (NGT) feeds. Program implementation, patient characteristics, and initial outcomes are described. STUDY DESIGN: Data was collected prospectively in this implementation study. Descriptive statistics define weight gain, number of NGT feed days, number of days on monitoring, and physician time spent. Patient characteristics, readmissions, and implementation details are described. RESULTS: One-hundred and four babies consented to and completed data collection. Average weight gain on monitoring was 31.4 g/day (SD 10.2). Eighty-nine babies (85.6%) achieved full oral feeds while on the program, requiring a median 5 NGT feed days (IQR 2-13) and a median 15 days on monitoring (IQR 11-27). Average physician time spent was 9.1 min per day (SD 3.7). Six babies (5.8%) had unscheduled readmissions while on the program. CONCLUSION: Remote monitoring programs can facilitate discharge for babies with continued NGT needs.


Assuntos
Nutrição Enteral , Intubação Gastrointestinal , Recém-Nascido , Humanos , Tempo de Internação , Aumento de Peso , Alta do Paciente
6.
Am J Perinatol ; 2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35617960

RESUMO

OBJECTIVE: Obtaining informed consent for clinical trials is challenging in acute clinical settings. For the VentFirst randomized clinical trial (assisting ventilation during delayed cord clamping for infants <29 weeks' gestation), we created an informational video that sites could choose to use to supplement the standard in-person verbal and written consent. Using a postconsent survey, we sought to describe the impact of the video on patient recruitment, satisfaction with the consent process, and knowledge about the study. STUDY DESIGN: This is a descriptive survey-based substudy. RESULTS: Of the sites participating in the VentFirst trial that obtained institutional review board (IRB) approval to allow use of the video to supplement the standard informed consent process, three elected to participate in the survey substudy. From February 2018 to January 2021, 82 women at these three sites were offered the video and completed the postconsent survey. Overall, 73 of these 82 women (89%) consented to participate in the primary study, 78 (95%) indicated the study was explained to them very well or extremely well, and the range of correct answers on five knowledge questions about the study was 63 to 98%. Forty-six (56%) of the 82 women offered the video chose to watch it. There were no major differences in study participation, satisfaction with the consent process, or knowledge about the study between the women who chose to watch or not watch the video. CONCLUSION: Watching an optional video to supplement the standard informed consent process did not have a major impact on outcomes in this small substudy. The ways in which audiovisual tools might modify the traditional informed consent process deserve further study. KEY POINTS: · Informed consent in acute clinical contexts is difficult.. · Videos offer an alternative communication tool.. · Continued research is necessary to optimize the consent process..

7.
Acad Med ; 97(4): 536-543, 2022 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-34261864

RESUMO

PURPOSE: In 2014, the Association of American Medical Colleges defined 13 Core Entrustable Professional Activities (EPAs) that all graduating students should be ready to do with indirect supervision upon entering residency and commissioned a 10-school, 5-year pilot to test implementing the Core EPAs framework. In 2019, pilot schools convened trained entrustment groups (TEGs) to review assessment data and render theoretical summative entrustment decisions for class of 2019 graduates. Results were examined to determine the extent to which entrustment decisions could be made and the nature of these decisions. METHOD: For each EPA considered (4-13 per student), TEGs recorded an entrustment determination (ready, progressing but not yet ready, evidence against student progressing, could not make a decision); confidence in that determination (none, low, moderate, high); and the number of workplace-based assessments (WBAs) considered (0->15) per determination. These individual student-level data were de-identified and merged into a multischool database; chi-square analysis tested the significance of associations between variables. RESULTS: The 2,415 EPA-specific determinations (for 349 students by 4 participating schools) resulted in a decision of ready (n = 997/2,415; 41.3%), progressing but not yet ready (n = 558/2,415; 23.1%), or evidence against student progression (n = 175/2,415; 7.2%). No decision could be made for the remaining 28.4% (685/2,415), generally for lack of data. Entrustment determinations' distribution varied across EPAs (chi-square P < .001) and, for 10/13 EPAs, WBA availability was associated with making (vs not making) entrustment decisions (each chi-square P < .05). CONCLUSIONS: TEGs were able to make many decisions about readiness for indirect supervision; yet less than half of determinations resulted in a decision of readiness to perform this EPA with indirect supervision. More work is needed at the 10 schools to enable authentic summative entrustment in the Core EPAs framework.


Assuntos
Educação de Graduação em Medicina , Internato e Residência , Competência Clínica , Educação Baseada em Competências , Tomada de Decisões , Humanos
8.
J Diabetes Sci Technol ; 15(2): 242-250, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33588608

RESUMO

BACKGROUND: Glucommander™ (GM), an electronic glycemic management system, was implemented across a multi-hospital health system as the standard of care for glycemic control. GM provides insulin dosing recommendations based on patient-specific blood glucose (BG) trends after providers select either a custom dose or weight-based multiplier as the initial dosing strategy for the first 24 hours. This study evaluated the impact of initial subcutaneous (SC) GM insulin dosing strategies on glycemic management. METHODS: Non-intensive care unit patients treated with SC GM using either initial custom (based on provider discretion) or weight-based multiplier settings (0.3, 0.5, or 0.7 units/kg/day) were evaluated in this retrospective chart review. The primary endpoint was time to target BG range defined as time to first two consecutive in range point of care BG. Secondary endpoints included percentage of BG values in target range, percentage of orders following institutional recommendations, length of stay (LOS), average BG, and incidence of hypoglycemia and hyperglycemia. RESULTS: A review of 348 patients showed time to target BG was not significantly different between custom and multiplier groups (55 vs 64 hours, P = .07). Target BG was achieved in less than half of patients in both groups (47% vs 44%, respectively). There were no differences in hospital LOS, proportion of BG in target range, rates of hypo/hyperglycemia, and average BG. CONCLUSIONS: Custom initial SC GM insulin dosing settings showed a nonsignificant decrease in time to target BG range compared to pre-defined multiplier settings. Future studies evaluating the impact of compliance with institutional recommendations on BG control are warranted.


Assuntos
Glicemia , Hipoglicemiantes , Algoritmos , Humanos , Insulina , Estudos Retrospectivos
9.
Glob Chang Biol ; 27(2): 435-453, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33112459

RESUMO

Plant litter chemistry is altered during decomposition but it remains unknown if these alterations, and thus the composition of residual litter, will change in response to climate. Selective microbial mineralization of litter components and the accumulation of microbial necromass can drive litter compositional change, but the extent to which these mechanisms respond to climate remains poorly understood. We addressed this knowledge gap by studying needle litter decomposition along a boreal forest climate transect. Specifically, we investigated how the composition and/or metabolism of the decomposer community varies with climate, and if that variation is associated with distinct modifications of litter chemistry during decomposition. We analyzed the composition of microbial phospholipid fatty acids (PLFAs) in the litter layer and measured natural abundance δ13 CPLFA values as an integrated measure of microbial metabolisms. Changes in litter chemistry and δ13 C values were measured in litterbag experiments conducted at each transect site. A warmer climate was associated with higher litter nitrogen concentrations as well as altered microbial community structure (lower fungi:bacteria ratios) and microbial metabolism (higher δ13 CPLFA ). Litter in warmer transect regions accumulated less aliphatic-C (lipids, waxes) and retained more O-alkyl-C (carbohydrates), consistent with enhanced 13 C-enrichment in residual litter, than in colder regions. These results suggest that chemical changes during litter decomposition will change with climate, driven primarily by indirect climate effects (e.g., greater nitrogen availability and decreased fungi:bacteria ratios) rather than direct temperature effects. A positive correlation between microbial biomass δ13 C values and 13 C-enrichment during decomposition suggests that change in litter chemistry is driven more by distinct microbial necromass inputs than differences in the selective removal of litter components. Our study highlights the role that microbial inputs during early litter decomposition can play in shaping surface litter contribution to soil organic matter as it responds to climate warming effects such as greater nitrogen availability.


Assuntos
Folhas de Planta , Solo , Fungos , Microbiologia do Solo , Taiga
10.
Med Sci Educ ; 30(1): 395-401, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34457683

RESUMO

One of the main goals of the CoreEPA pilot has been to determine the feasibility of developing a process to make summative entrustment decisions regarding entrustable professional activities (EPAs). Five years into the pilot, we report results of a research study we conducted to explore approaches to the entrustment process undertaken by our ten participating schools. We sought to identify the choices that participating schools made regarding the entrustment process and why these decisions were made. We are sharing these results, highlighting ongoing challenges that were identified with the intent of helping other medical schools that are moving toward EPA-based assessment. We conducted semi-structured interviews with representatives of all 10 medical schools in the CoreEPA pilot to understand their choices in designing the entrustment process. Additional information was obtained through follow-up communication to ensure completeness and accuracy of the findings. Several common themes are described. Our results indicate that, while approaches to the entrustment process vary considerably, all schools demonstrated consistent adherence to the guiding principles of the pilot. Several common barriers to the entrustment process emerged, and there was a consensus that more experience is needed with the process before consequential entrustment decisions can be made. The CoreEPA pilot schools continue to address challenges identified in implementing entrustment processes and making entrustment decisions for our students graduating in the Class of 2020.

11.
BMC Res Notes ; 12(1): 550, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31470895

RESUMO

OBJECTIVE: The purpose of this study was to develop and validate a specific and sensitive liquid chromatography tandem mass-spectrometry method for quantification of usnic acid concentration in the lichen, Cladonia uncialis, suitable for detection of relatively small fluctuations of usnic acid concentration in response to environmental changes. RESULTS: The resulting method was fully validated according to international guidelines and demonstrated good selectivity and sensitivity with minor levels of a matrix effect and high accuracy.


Assuntos
Benzofuranos/análise , Cromatografia Líquida/métodos , Líquens/química , Espectrometria de Massas em Tandem/métodos , Bioensaio , Padrões de Referência
13.
Glob Chang Biol ; 24(2): e458-e473, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28871609

RESUMO

Warmer climates have been associated with reduced bioreactivity of soil organic matter (SOM) typically attributed to increased diagenesis; the combined biological and physiochemical transformation of SOM. In addition, cross-site studies have indicated that ecosystem regime shifts, associated with long-term climate warming, can affect SOM properties through changes in vegetation and plant litter production thereby altering the composition of soil inputs. The relative importance of these two controls, diagenesis and inputs, on SOM properties as ecosystems experience climate warming, however, remains poorly understood. To address this issue we characterized the elemental, chemical (nuclear magnetic resonance spectroscopy and total hydrolysable amino acids analysis), and isotopic composition of plant litter and SOM across a well-constrained mesic boreal forest latitudinal transect in Atlantic Canada. Results across forest sites within each of three climate regions indicated that (1) climate history and diagenesis affect distinct parameters of SOM chemistry, (2) increases in SOM bioreactivity with latitude were associated with elevated proportions of carbohydrates relative to plant waxes and lignin, and (3) despite the common forest type across regions, differences in SOM chemistry by climate region were associated with chemically distinct litter inputs and not different degrees of diagenesis. The observed climate effects on vascular plant litter chemistry, however, explained only part of the regional differences in SOM chemistry, most notably the higher protein content of SOM from warmer regions. Greater proportions of lignin and aliphatic compounds and smaller proportions of carbohydrates in warmer sites' soils were explained by the higher proportion of vascular plant relative to moss litter in the warmer relative to cooler forests. These results indicate that climate change induced decreases in the proportion of moss inputs not only impacts SOM chemistry but also increases the resistance of SOM to decomposition, thus significantly altering SOM cycling in these boreal forest soils.


Assuntos
Florestas , Solo/química , Taiga , Canadá , Mudança Climática
15.
Acad Med ; 92(6): 774-779, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28557941

RESUMO

PROBLEM: To better prepare graduating medical students to transition to the professional responsibilities of residency, 10 medical schools are participating in an Association of American Medical Colleges pilot to evaluate the feasibility of explicitly teaching and assessing 13 Core Entrustable Professional Activities for Entering Residency. The authors focused on operationalizing the concept of entrustment as part of this process. APPROACH: Starting in 2014, the Entrustment Concept Group, with representatives from each of the pilot schools, guided the development of the structures and processes necessary for formal entrustment decisions associated with students' increased responsibilities at the start of residency. OUTCOMES: Guiding principles developed by the group recommend that formal, summative entrustment decisions in undergraduate medical education be made by a trained group, be based on longitudinal performance assessments from multiple assessors, and incorporate day-to-day entrustment judgments by workplace supervisors. Key to entrustment decisions is evidence that students know their limits (discernment), can be relied on to follow through (conscientiousness), and are forthcoming despite potential personal costs (truthfulness), in addition to having the requisite knowledge and skills. The group constructed a developmental framework for discernment, conscientiousness, and truthfulness to pilot a model for transparent entrustment decision making. NEXT STEPS: The pilot schools are studying a number of questions regarding the pathways to and decisions about entrustment. This work seeks to inform meaningful culture change in undergraduate medical education through a shared understanding of the assessment of trust and a shared trust in that assessment.


Assuntos
Competência Clínica/normas , Educação de Graduação em Medicina/organização & administração , Avaliação Educacional/normas , Internato e Residência/organização & administração , Competência Profissional/normas , Sociedades Médicas/normas , Adulto , Feminino , Humanos , Masculino , Projetos Piloto , Avaliação de Programas e Projetos de Saúde , Estados Unidos , Adulto Jovem
17.
J Perinat Neonatal Nurs ; 30(3): 237-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27465457

RESUMO

Since the Institute of Medicine published Crossing the Quality Chasm in 2001, healthcare systems have become more focused on improving the quality of healthcare delivery. At Oregon Health & Science University and Doernbecher Children's Hospital, we recognize the need to take an interprofessional, team-based approach to improving the care we provide to our current and future patients. We describe here an ongoing quality improvement project in the Doernbecher Neonatal Intensive Care Unit (NICU), with specific attention to the factors we believe have contributed to the implementation and early success of the project. These factors include the history of quality improvement work in our NICU and in the field of neonatology, the "dyad leadership" structure under which we operate in our NICU, and our developing understanding of the concept of "team intelligence." These elements have led to the formation of a team that can practice shared decision making and work as one to realize a shared goal.


Assuntos
Tomada de Decisões , Atenção à Saúde , Terapia Intensiva Neonatal , Equipe de Assistência ao Paciente , Atenção à Saúde/métodos , Atenção à Saúde/normas , Inteligência Emocional , Humanos , Unidades de Terapia Intensiva Neonatal/normas , Terapia Intensiva Neonatal/métodos , Terapia Intensiva Neonatal/psicologia , Terapia Intensiva Neonatal/normas , Oregon , Inovação Organizacional , Objetivos Organizacionais , Equipe de Assistência ao Paciente/organização & administração , Equipe de Assistência ao Paciente/normas , Melhoria de Qualidade
18.
Pediatrics ; 132(1): e128-34, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23733796

RESUMO

BACKGROUND AND OBJECTIVES: Hypothermia contributes to neonatal mortality and morbidity, especially in preterm and low birth weight infants in developing countries. Plastic bags covering the trunk and extremities of very low birth weight infants reduces hypothermia. This technique has not been studied in larger infants or in many resource-limited settings. The objective was to determine if placing preterm and low birth weight infants inside a plastic bag at birth maintains normothermia. METHODS: Infants at 26 to 36 weeks' gestational age and/or with a birth weight of 1000 to 2500 g born at the University Teaching Hospital in Lusaka, Zambia, were randomized by using a 1:1 allocation and parallel design to standard thermoregulation (blanket or radiant warmer) care or to standard thermoregulation care plus placement inside a plastic bag at birth. The primary outcome measure was axillary temperature in the World Health Organization-defined normal range (36.5-37.5°C) at 1 hour after birth. RESULTS: A total of 104 infants were randomized. At 1 hour after birth, infants randomized to plastic bag (n = 49) were more likely to have a temperature in the normal range as compared with infants in the standard thermoregulation care group (n = 55; 59.2% vs 32.7%; relative risk 1.81; 95% confidence interval 1.16-2.81; P = .007). The temperature at 1 hour after birth in the infants randomized to plastic bag was 36.5 ± 0.5°C compared with 36.1 ± 0.6°C in standard care infants (P < .001). Hyperthermia (>38.0°C) did not occur in any infant. CONCLUSIONS: Placement of preterm/low birth weight infants inside a plastic bag at birth compared with standard thermoregulation care reduced hypothermia without resulting in hyperthermia, and is a low-cost, low-technology tool for resource-limited settings.


Assuntos
Países em Desenvolvimento , Hipotermia/prevenção & controle , Recém-Nascido de Baixo Peso , Doenças do Prematuro/prevenção & controle , Assistência Perinatal/métodos , Polietileno , Regulação da Temperatura Corporal , Método Duplo-Cego , Feminino , Idade Gestacional , Humanos , Hipotermia/etiologia , Recém-Nascido de Baixo Peso/fisiologia , Recém-Nascido , Doenças do Prematuro/etiologia , Doenças do Prematuro/fisiopatologia , Masculino , Zâmbia
19.
J Agric Food Chem ; 61(3): 492-500, 2013 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-23259687

RESUMO

This study investigates the analysis of thiol compounds using a needle trap device (HS-NTD) and solid-phase microextraction (HS-SPME) derivatized headspace techniques coupled to GC-MS. Thiol compounds and their outgassed products are particularly difficult to monitor in foodstuffs. It was found that with in-needle and in-fiber derivatization, using the derivatization agent N-phenylmaleimide, it was possible to enhance the selectivity toward thiol, which allowed the quantitation of butanethiol, ethanethiol, methanethiol, and propanethiol compounds found in fresh garlic. A side-hole NTD was prepared and packed in house and utilized mixed DVB and Carboxen polymer extraction phases made of 60-80 mesh particles. NTD sampling was accomplished in the exhaustive sampling mode, where breakthrough was negligible. This work demonstrates a new application for a side-hole NTD sampling. A commercial mixed polymer phase of polydimethylsiloxane (PDMS) and divinylbenzene polymer (DVB) SPME fiber was used for SPME extractions. Under optimized derivatization, extraction, and analysis conditions for both NTD-GC-MS and SPME-GC-MS techniques, automated sampling methods were developed for quantitation. Both methods demonstrate a successful approach to thiol determination and provide a quantitative linear response between <0.1 and 10 mg L(-1) (R(2) = 0.9996), with limits of detection (LOD) in the low micrograms per liter range for the investigated thiols. Addition methods using known spiked quantities of thiol analytes in ground garlic facilitated method validation. Carry-over was also negligible for both SPME and NTD under optimized conditions.


Assuntos
Alho/química , Compostos de Sulfidrila/química , Dimetilpolisiloxanos/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Reprodutibilidade dos Testes , Microextração em Fase Sólida/métodos , Compostos de Vinila/química
20.
Anal Chim Acta ; 742: 22-9, 2012 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-22884203

RESUMO

A fully automated cold fiber solid phase microextraction device has been developed by coupling to a GERSTEL multipurpose (MPS 2) autosampler and applied to the analysis of volatiles and semi-volatiles in aqueous and solid matrices. The proposed device was thoroughly evaluated for its extraction performance, robustness, reproducibility and reliability by gas chromatograph/mass spectrometer (GC/MS). With the use of a septumless head injector, the entire automated setup was capable of analyzing over 200 samples without any GC injector leakages. Evaluation of the automated cold fiber device was carried out using a group of compounds characterized by different volatilities and polarities. Extraction efficiency as well as analytical figures of merit was compared to commercial solid phase microextraction fibers. The automated cold fiber device showed significantly improved extraction efficiency compared to the commercial polydimethylsiloxane (PDMS) and cold fiber without cooling for the analysis of aqueous standard samples due to the low temperature of the coating. Comparing results obtained from cold fiber and commercial divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber temperature profile demonstrated that the temperature gap between the sample matrix and the coating improved the distribution coefficient and therefore the extraction amount. The linear dynamic range of the cold fiber device was 0.5 ng mL(-1) to 100 ng mL(-1) with a linear regression coefficient ≥0.9963 for all compounds. The limit of detection for all analytes ranged from 1.0 ng mL(-1) to 9.4 ng mL(-1). The newly automated cold fiber device presents a platform for headspace analysis of volatiles and semi-volatiles for large number of samples with improved throughput and sensitivity.

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