Accelerated Solvent Extraction for Sample Preparation of Chemical Weapon Degradation Compounds
Notice bibliographique
Résumé
EXTENDED ABSTRACT A commercially available accelerated solvent extractor (Dionex ASE 200) was utilized for rapid soil extraction of degradation compounds originating from Schedule 1 Chemical Weapons (CW) materials listed under the Chemical Weapons Convention (CWC). Inert 2030 mesh Ottawa sand (Fisher Scientific) and three types of characterized soils including sandy loam, sandy clayloam, and loam (soil #1, #2, and #3, respectively from : RT Corporation) were spiked with part-per-million (ppm) quantities of various degradation compounds, including, but not limited to, methyl phosphonic acid (MPA) and thiodiglycol (TDG). The degradation compounds extracted from the soils were derivitized with 2,2,2-trifluoroN,N-bis(trimethylsilyl)-acetamide (BSTFA) and analyzed via gas chromatography/mass spectrometry (GC-MS) in order to determine percent recoveries and optimize the efficiency of the extractions. Results of these studies include recovery data and optimized methodology. In general, highest recoveries of the target compounds were achieved with extraction temperatures of 100°C and 150°C. Higher temperatures produced lower recoveries, possibly due to breakdown of the target compounds and interference caused by the extraction of large amounts of extraneous organic compounds. Percent recoveries obtained from soil #2 were poor for all target compounds. Inert sand and soil #1 yielded the highest recoveries for most target compounds. The target compounds originating from mustard agents demonstrated the highest recovery percentage (50-90%) of the target compounds investigated here. In addition, an environmental weathering study of spiked soils was performed to evaluate extraction efficiency following weeks of exposure to atmosphere. As expected, trends observed over time exhibit a decrease in percent recovery as exposure time is increased. However, most target compounds were detected at low concentrations after as long as six weeks of exposure to atmosphere in at least one of three sample replicates. The advantages of accelerated solvent extraction (ASE) over other soil extraction methods include a fullyautomated solvent extraction system, fast solvent extractions achieved in minutes, low volumes of solvent required, and good recoveries of compounds originating from mustard agents. However, the disadvantages of ASE extraction include the initial equipment costs and maintenance, moderate to poor recoveries of many target compounds originating from nerve agents, and poor recoveries of all target compounds achieved from soil #2. Although recoveries were poor for some compounds, detection of the target compounds was achieved following ASE extraction in all soil matrices with the exception of MPA (see Table I).
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,002 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,013 | 0,005 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».