Notice bibliographique
Résumé
Arsenic determination in some marine algae of British Columbia was carried out by using Hydride Generation and Graphite Furnace Atomic Absorption Spectrometzy (HGAAS and GFAAS) following a two-hour wet digestion procedure. The total arsenic concentration in Fucus distichus and other brown algae determined by using the continuous HGAAS was found to vary with species and the collection sites, ranging from 1.8 μg/g As to 36.9 μg/g As (dry weight basis). Similarly, the arsenic concentrations determined in red algae were found to vary from a low 1.3 μg/g As to a high 39.7 μg/g As (also on a dry weight basis). Also, the arsenic concentrations determined in green algae were found to vary quite widely as in the other two classes of macroalgae, ranging from 0 μg/g As (not detected) to 27.2 μg/g As. These widely varying arsenic concentration results suggest that the amount of arsenic accumulated by seaweed is not only related to the class of the macroalgae as well as the particular species, but also to the sampling location and its soil conditions. Both the continuous HGAA and the semi-continuous HG-GC-AA techniques were employed for the examination of the selective reduction of four arsenic species, namely arsenate [As(V)], arsenite [As(III)], monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). The response profiles of the four arsenic species were plotted and the optimum arsenic analytical conditions were determined from these plots. By using a combination of extraction followed with sodium hydroxide digestion of the freeze dried seaweed, the reducible and “hidden” arsenic species in the extracts and digests were determined by using the semi-continuous mode HG-GC-AAS. Greater than 90% of the total arsenic in the seaweeds was found in the “hidden” arsenic forms. On-line detection techniques of High Performance Liquid Chromatography Microwave Oven Assisted Decomposition Hydride Generation Atomic Absorption Spectrometry (HPLC-Mic-HGAAS) and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICPMS) were employed for the characterization of arsenic species in water soluble extract of F. distichus collected from Head of Hastings Arm, British Columbia. Prior to the use of these techniques for arsenic species identification, arsenic containing fractions were isolated via the use of several combinations of chromatographic procedures such as gel permeation chromatography (gpc), ion exchange chromatography (IEC), thin layer chromatography (tlc) and reverse phase high performance liquid chromatography (HPLC). The water soluble extract of F. distichus was found to contain two major arsenosugars*, 11a and 11b, as well as several minor, unidentified arsenic species, likely to be other arsenosugar derivatives. The biotransformation studies of “hidden” organoarsenicals in F. distichus were carried out by using anaerobic decomposition conditions in “open” and “closed” systems. Two arsenic species, 2-dimethylarsinylethanol (DMAE) and dimethylarsiic acid (DMAA) were identified from the “open” system decomposition products by using the HPLC ICPMS technique. In the “closed” system, DMAE was characterized as a major decomposition product and DMAA was observed as another main component. Other minor arsenic species were found in the decomposition products, however, these were not identified. [chemical compound diagrams]
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,002 |
| Études des sciences et des technologies | 0,002 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
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 ».